Showing 1–50 of 64 results for author: Boes, P

PICKLES: a Natural Language Framework for Requirement Specification and Model-Based Testing

Authors: María Belén Rodríguez, Petra van den Bos

Abstract: This paper combines methods from the fields of Model-Based Testing (MBT) and Behaviour-Driven Development (BDD) to define a testing approach with human-readable specifications and test cases, as in BDD, while using the modelling techniques and automatic test generation algorithms from MBT. We introduce PICKLES, a Precise Input and Control-flow Keyword-based Language for tEst Scenarios; an extensio… ▽ More This paper combines methods from the fields of Model-Based Testing (MBT) and Behaviour-Driven Development (BDD) to define a testing approach with human-readable specifications and test cases, as in BDD, while using the modelling techniques and automatic test generation algorithms from MBT. We introduce PICKLES, a Precise Input and Control-flow Keyword-based Language for tEst Scenarios; an extension of Gherkin-style BDD scenarios, specified in structured natural language. We provide a bi-directional translation from Pickles scenarios to formal models, where both specifications and tests are human-readable, and a method to obtain a so-called master model combining all translated scenarios. Standard MBT algorithms can then be applied to automatically derive test cases from it. We implement a prototype of the translation and composition steps, which we use on an industrial case study: a software component from a traffic management system. With it, we illustrate the pipeline and show how Pickles can achieve significantly higher coverage with respect to BDD from the same set of scenarios. △ Less

Submitted 29 April, 2026; originally announced April 2026.

Comments: 14 pages, 4 figures

ACM Class: D.2.5; D.2.1

Towards Low-Energy Electron High-Resolution Spectroscopy with Transition-Edge Sensors

Authors: R. Ammendola, A. Apponi, G. Benato, M. G. Betti, R. Biondi, P. Bos, M. Cadeddu, A. Casale, O. Castellano, G. Cavoto, L. Cecchini, E. Celasco, M. Chirico, W. Chung, A. G. Cocco, A. P. Colijn, B. Corcione, N. D'Ambrosio, M. D'Incecco, G. De Bellis, M. De Deo, N. de Groot, A. Esposito, M. Farino, S. Farinon , et al. (40 additional authors not shown)

Abstract: We present a study of the energy resolution of transition-edge sensors (TESs) for the detection of electrons in the 100 eV kinetic energy range. The TES is a Ti-Au bilayer with an active area of $(60 \times 60)$ $μ\text{m}^2$ and a critical temperature of $\sim$ 80 mK. The electron source is based on vertically-aligned multiwall carbon nanotubes located inside the cryostat, with electrons generate… ▽ More We present a study of the energy resolution of transition-edge sensors (TESs) for the detection of electrons in the 100 eV kinetic energy range. The TES is a Ti-Au bilayer with an active area of $(60 \times 60)$ $μ\text{m}^2$ and a critical temperature of $\sim$ 80 mK. The electron source is based on vertically-aligned multiwall carbon nanotubes located inside the cryostat, with electrons generated via field emission. For electrons in the (92 - 99) eV kinetic energy range, we obtain a Gaussian energy resolution for fully-absorbed electrons of (0.479 $\pm$ 0.041 $\pm$ 0.055) eV. When considering the full-width at half-maximum of the peak, the corresponding resolution is of (1.44 $\pm$ 0.17 $\pm$ 0.27) eV. The former represents an improvement of (46 - 60)% with respect to previous results, and is mainly attributed to the reduction in the TES active area. The latter is instead an improvement of over a factor of 20, and is mainly due to the reduction in the emitting area of the electron source, which significantly suppresses electron back-scattering in proximity of the TES. These results represent a major milestone toward high-precision spectroscopy on low-energy electrons, which is a key objective for the PTOLEMY experiment. △ Less

Submitted 25 February, 2026; originally announced February 2026.

Comments: 6 pages, 4 figures

Disjunction Composition of BDD Transition Systems for Model-Based Testing

Authors: Tannaz Zameni, Petra van den Bos, Arend Rensink

Abstract: We introduce a compositional approach to model-based test generation in Behavior-Driven Development (BDD). BDD is an agile methodology in which system behavior is specified through textual scenarios that, in our approach, are translated into transition systems used for model-based testing. This paper formally defines disjunction composition, to combine BDD transition systems that represent alterna… ▽ More We introduce a compositional approach to model-based test generation in Behavior-Driven Development (BDD). BDD is an agile methodology in which system behavior is specified through textual scenarios that, in our approach, are translated into transition systems used for model-based testing. This paper formally defines disjunction composition, to combine BDD transition systems that represent alternative system behaviors. Disjunction composition allows for modeling and testing the integrated behavior while ensuring that the testing power of the original set of scenarios is preserved. This is proved using a symbolic semantics for BDD transition systems, with the property that the symbolic equivalence of two BDD transition systems guarantees that they fail the same test cases. Also, we demonstrate the potential of disjunction composition by applying the composition in an industrial case study. △ Less

Submitted 19 February, 2026; originally announced February 2026.

Comments: Technical report with proofs

From big q-Jacobi and Chebyshev polynomials to exponential-reproducing subdivision: new identities

Authors: Leonard Peter Bos, Lucia Romani, Alberto Viscardi

Abstract: In this paper we derive new identities satisfied by Chebyshev polynomials of the first kind and big q-Jacobi polynomials. An immediate benefit of the derived identities is the achievement of closed-form expressions for the Laurent polynomials that identify minimum-support interpolating subdivision schemes reproducing finite sets of integer powers of exponentials. In this paper we derive new identities satisfied by Chebyshev polynomials of the first kind and big q-Jacobi polynomials. An immediate benefit of the derived identities is the achievement of closed-form expressions for the Laurent polynomials that identify minimum-support interpolating subdivision schemes reproducing finite sets of integer powers of exponentials. △ Less

Submitted 20 January, 2026; originally announced January 2026.

Ultra-high precision high voltage system for PTOLEMY

Authors: R. Ammendola, A. Apponi, G. Benato, M. G. Betti, R. Biondim, P. Bos, G. Cavoto, M. Cadeddu, A. Casale, O. Castellano, E. Celasco, L. Cecchini, M. Chirico, W. Chung, A. G. Cocco, A. P. Colijn, B. Corcione, N. D'Ambrosio, M. D'Incecco, G. De Bellis, M. De Deo, N. de Groot, A. Esposito, M. Farino, S. Farinon , et al. (41 additional authors not shown)

Abstract: The PTOLEMY project is prototyping a novel electromagnetic filter for high-precision $β$ spectroscopy, with the ultimate and ambitious long-term goal of detecting the cosmic neutrino background through electron capture on tritium bound to graphene. Intermediate small-scale prototypes can achieve competitive sensitivity to the effective neutrino mass, even with reduced energy resolution. To reach a… ▽ More The PTOLEMY project is prototyping a novel electromagnetic filter for high-precision $β$ spectroscopy, with the ultimate and ambitious long-term goal of detecting the cosmic neutrino background through electron capture on tritium bound to graphene. Intermediate small-scale prototypes can achieve competitive sensitivity to the effective neutrino mass, even with reduced energy resolution. To reach an energy resolution better than \SI{500}{meV} at the tritium $β$-spectrum endpoint of \SI{18.6}{keV}, and accounting for all uncertainties in the filtering chain, the electrode voltage must be controlled at the level of a few parts per million and monitored in real time. In this work, we present the first results obtained in this effort, using a chain of commercial ultra-high-precision voltage references, read out by precision multimeters and a \emph{field mill} device. The currently available precision on high voltage is, in the conservative case, as low as \SI{0.2}{ppm} per \SI{1}{kV} single board and $\lesssim$ \SI{50}{mV} over the \SI{10}{kV} series, presently limited by field mill read-out noise. However, assuming uncorrelated Gaussian noise extrapolation, the real precision could in principle be as low as \SI{0.05}{ppm} over \SI{20}{kV}. △ Less

Submitted 22 December, 2025; originally announced December 2025.

Comments: 17 pages, 13 figures

Systematic Evaluation of Black-Box Checking for Fast Bug Detection

Authors: Bram Pellen, María Belén Rodríguez, Frits Vaandrager, Petra van den Bos

Abstract: Combinations of active automata learning, model-based testing and model checking have been successfully used in numerous applications, e.g., for spotting bugs in implementations of major network protocols and to support refactoring of embedded controllers. However, in the large majority of these applications, model checking is only used at the very end, when no counterexample can be found anymore… ▽ More Combinations of active automata learning, model-based testing and model checking have been successfully used in numerous applications, e.g., for spotting bugs in implementations of major network protocols and to support refactoring of embedded controllers. However, in the large majority of these applications, model checking is only used at the very end, when no counterexample can be found anymore for the latest hypothesis model. This contrasts with the original proposal of black-box checking (BBC) by Peled, Vardi & Yannakakis, which applies model checking for all hypotheses, also the intermediate ones. In this article, we present the first systematic evaluation of the ability of BBC to find bugs quickly, based on 77 benchmarks models from real protocol implementations and controllers for which specifications of safety properties are available. Our main finding are: (a) In cases where the full model can be learned, BBC detects violations of the specifications with just 3.4% of the queries needed by an approach in which model checking is only used for the full model. (b) Even when the full model cannot be learned, BBC is still able to detect many violations of the specification. In particular, BBC manages to detect 94% of the safety properties violations in the challenging RERS 2019 industrial LTL benchmarks. (c) Our results also confirm that BBC is way more effective than existing MBT algorithms in finding deep bugs in implementations. △ Less

Submitted 8 December, 2025; originally announced December 2025.

Comments: 23 pages, 4 figures

MSC Class: 68Q45 ACM Class: D.2.5; F.4.3

Solving the Right Problem with Multi-Robot Formations

Authors: Chaz Cornwall, Jeremy P. Bos

Abstract: Formation control simplifies minimizing multi-robot cost functions by encoding a cost function as a shape the robots maintain. However, by reducing complex cost functions to formations, discrepancies arise between maintaining the shape and minimizing the original cost function. For example, a Diamond or Box formation shape is often used for protecting all members of the formation. When more inform… ▽ More Formation control simplifies minimizing multi-robot cost functions by encoding a cost function as a shape the robots maintain. However, by reducing complex cost functions to formations, discrepancies arise between maintaining the shape and minimizing the original cost function. For example, a Diamond or Box formation shape is often used for protecting all members of the formation. When more information about the surrounding environment becomes available, a static shape often no longer minimizes the original protection cost. We propose a formation planner to reduce mismatch between a formation and the cost function while still leveraging efficient formation controllers. Our formation planner is a two-step optimization problem that identifies desired relative robot positions. We first solve a constrained problem to estimate non-linear and non-differentiable costs with a weighted sum of surrogate cost functions. We theoretically analyze this problem and identify situations where weights do not need to be updated. The weighted, surrogate cost function is then minimized using relative positions between robots. The desired relative positions are realized using a non-cooperative formation controller derived from Lyapunov's direct approach. We then demonstrate the efficacy of this approach for military-like costs such as protection and obstacle avoidance. In simulations, we show a formation planner can reduce a single cost by over 75%. When minimizing a variety of cost functions simultaneously, using a formation planner with adaptive weights can reduce the cost by 20-40%. Formation planning provides better performance by minimizing a surrogate cost function that closely approximates the original cost function instead of relying on a shape abstraction. △ Less

Submitted 29 October, 2025; originally announced October 2025.

Comments: Submitted to SAE WCX 2026

Performance Characterization of a Point-Cloud-Based Path Planner in Off-Road Terrain

Authors: Casey D. Majhor, Jeremy P. Bos

Abstract: We present a comprehensive evaluation of a point-cloud-based navigation stack, MUONS, for autonomous off-road navigation. Performance is characterized by analyzing the results of 30,000 planning and navigation trials in simulation and validated through field testing. Our simulation campaign considers three kinematically challenging terrain maps and twenty combinations of seven path-planning parame… ▽ More We present a comprehensive evaluation of a point-cloud-based navigation stack, MUONS, for autonomous off-road navigation. Performance is characterized by analyzing the results of 30,000 planning and navigation trials in simulation and validated through field testing. Our simulation campaign considers three kinematically challenging terrain maps and twenty combinations of seven path-planning parameters. In simulation, our MUONS-equipped AGV achieved a 0.98 success rate and experienced no failures in the field. By statistical and correlation analysis we determined that the Bi-RRT expansion radius used in the initial planning stages is most correlated with performance in terms of planning time and traversed path length. Finally, we observed that the proportional variation due to changes in the tuning parameters is remarkably well correlated to performance in field testing. This finding supports the use of Monte-Carlo simulation campaigns for performance assessment and parameter tuning. △ Less

Submitted 8 September, 2025; originally announced September 2025.

Comments: This work has been published in the Journal of Field Robotics

Time for Quiescence: Modelling quiescent behaviour in testing via time-outs in timed automata

Authors: Laura Brandán Briones, Marcus Gerhold, Petra van den Bos, Mariëlle Stoelinga

Abstract: Model-based testing (MBT) derives test suites from a behavioural specification of the system under test. In practice, engineers favour simple models, such as labelled transition systems (LTSs). However, to deal with quiescence - the absence of observable output - in practice, a time-out needs to be set to conclude observation of quiescence. Timed MBT exists, but it typically relies on the full ars… ▽ More Model-based testing (MBT) derives test suites from a behavioural specification of the system under test. In practice, engineers favour simple models, such as labelled transition systems (LTSs). However, to deal with quiescence - the absence of observable output - in practice, a time-out needs to be set to conclude observation of quiescence. Timed MBT exists, but it typically relies on the full arsenal of timed automata (TA). We present a lifting operator $χ^{\scriptstyle M}\!$ that adds timing without the TA overhead: given an LTS, $χ^{\scriptstyle M}\!$ introduces a single clock for a user chosen time bound $M>0$ to declare quiescence. In the timed automaton, the clock is used to model that outputs should happen before the clock reaches value $M$, while quiescence occurs exactly at time $M$. This way we provide a formal basis for the industrial practice of choosing a time-out to conclude quiescence. Our contributions are threefold: (1) an implementation conforms under $\mathbf{ioco}$ if and only if its lifted version conforms under timed $\mathbf{tioco_M}$ (2) applying $χ^{\scriptstyle M}\!$ before or after the standard $\mathbf{ioco}$ test-generation algorithm yields the same set of tests, and (3) the lifted TA test suite and the original LTS test suite deliver identical verdicts for every implementation. △ Less

Submitted 24 July, 2025; originally announced July 2025.

Thermal operations from informational equilibrium

Authors: Seok Hyung Lie, Jeongrak Son, Paul Boes, Nelly H. Y. Ng, Henrik Wilming

Abstract: Thermal operations are quantum channels that have taken a prominent role in deriving fundamental thermodynamic limitations in quantum systems. We show that these channels are uniquely characterized by a purely quantum information theoretic property: They admit a dilation into a unitary process that leaves the environment invariant when applied to the equilibrium state. In other words, they are the… ▽ More Thermal operations are quantum channels that have taken a prominent role in deriving fundamental thermodynamic limitations in quantum systems. We show that these channels are uniquely characterized by a purely quantum information theoretic property: They admit a dilation into a unitary process that leaves the environment invariant when applied to the equilibrium state. In other words, they are the only channels that preserve equilibrium between system and environment. Extending this perspective, we explore an information theoretic idealization of heat bath behavior, by considering channels where the environment remains locally invariant for every initial state of the system. These are known as catalytic channels. We show that catalytic channels provide a refined hierarchy of Gibbs-preserving maps for fully-degenerate Hamiltonians, and are closely related to dual unitary quantum circuits. △ Less

Submitted 22 July, 2025; originally announced July 2025.

Comments: 5+7 pages; comments welcome

Journal ref: Phys. Rev. Lett. 137, 030403 (2026)

Explainable embeddings with Distance Explainer

Authors: Christiaan Meijer, E. G. Patrick Bos

Abstract: While eXplainable AI (XAI) has advanced significantly, few methods address interpretability in embedded vector spaces where dimensions represent complex abstractions. We introduce Distance Explainer, a novel method for generating local, post-hoc explanations of embedded spaces in machine learning models. Our approach adapts saliency-based techniques from RISE to explain the distance between two em… ▽ More While eXplainable AI (XAI) has advanced significantly, few methods address interpretability in embedded vector spaces where dimensions represent complex abstractions. We introduce Distance Explainer, a novel method for generating local, post-hoc explanations of embedded spaces in machine learning models. Our approach adapts saliency-based techniques from RISE to explain the distance between two embedded data points by assigning attribution values through selective masking and distance-ranked mask filtering. We evaluate Distance Explainer on cross-modal embeddings (image-image and image-caption pairs) using established XAI metrics including Faithfulness, Sensitivity/Robustness, and Randomization. Experiments with ImageNet and CLIP models demonstrate that our method effectively identifies features contributing to similarity or dissimilarity between embedded data points while maintaining high robustness and consistency. We also explore how parameter tuning, particularly mask quantity and selection strategy, affects explanation quality. This work addresses a critical gap in XAI research and enhances transparency and trustworthiness in deep learning applications utilizing embedded spaces. △ Less

Submitted 7 July, 2026; v1 submitted 21 May, 2025; originally announced May 2025.

Comments: 21 pages, 12 figures. Accepted to the 4th World Conference on eXplainable Artificial Intelligence. Method implementation: https://research-software-directory.org/software/distance-explainer

MSC Class: 68T99 ACM Class: I.2.m

Verified Parameterized Choreographies Technical Report

Authors: Robert Rubbens, Petra van den Bos, Marieke Huisman

Abstract: This technical report contains the full set of definitions and projection rules of the paper ``Verified Parameterized Choreographies'' by Rubbens et al. It also supplements the artefact. This technical report contains the full set of definitions and projection rules of the paper ``Verified Parameterized Choreographies'' by Rubbens et al. It also supplements the artefact. △ Less

Submitted 15 April, 2025; v1 submitted 21 February, 2025; originally announced February 2025.

Comments: Changes 2025-04-15: - Updated DOI to artefact

Multifractal Terrain Generation for Evaluating Autonomous Off-Road Ground Vehicles

Authors: Casey D. Majhor, Jeremy P. Bos

Abstract: We present a multifractal artificial terrain generation method that uses the 3D Weierstrass-Mandelbrot function to control roughness. By varying the fractal dimension used in terrain generation across three different values, we generate 60 unique off-road terrains. We use gradient maps to categorize the roughness of each terrain, consisting of low-, semi-, and high-roughness areas. To test how the… ▽ More We present a multifractal artificial terrain generation method that uses the 3D Weierstrass-Mandelbrot function to control roughness. By varying the fractal dimension used in terrain generation across three different values, we generate 60 unique off-road terrains. We use gradient maps to categorize the roughness of each terrain, consisting of low-, semi-, and high-roughness areas. To test how the fractal dimension affects the difficulty of vehicle traversals, we measure the success rates, vertical accelerations, pitch and roll rates, and traversal times of an autonomous ground vehicle traversing 20 randomized straight-line paths in each terrain. As we increase the fractal dimension from 2.3 to 2.45 and from 2.45 to 2.6, we find that the median area of low-roughness terrain decreases 13.8% and 7.16%, the median area of semi-rough terrain increases 11.7% and 5.63%, and the median area of high-roughness terrain increases 1.54% and 3.33%, all respectively. We find that the median success rate of the vehicle decreases 22.5% and 25% as the fractal dimension increases from 2.3 to 2.45 and from 2.45 to 2.6, respectively. Successful traversal results show that the median root-mean-squared vertical accelerations, median root-mean-squared pitch and roll rates, and median traversal times all increase with the fractal dimension. △ Less

Submitted 3 January, 2025; originally announced January 2025.

Comments: This work has been accepted for publication in ASME Journal of Autonomous Vehicles and Systems

FARSEC: A Reproducible Framework for Automatic Real-Time Vehicle Speed Estimation Using Traffic Cameras

Authors: Lucas Liebe, Franz Sauerwald, Sylwester Sawicki, Matthias Schneider, Leo Schuhmann, Tolga Buz, Paul Boes, Ahmad Ahmadov, Gerard de Melo

Abstract: Estimating the speed of vehicles using traffic cameras is a crucial task for traffic surveillance and management, enabling more optimal traffic flow, improved road safety, and lower environmental impact. Transportation-dependent systems, such as for navigation and logistics, have great potential to benefit from reliable speed estimation. While there is prior research in this area reporting competi… ▽ More Estimating the speed of vehicles using traffic cameras is a crucial task for traffic surveillance and management, enabling more optimal traffic flow, improved road safety, and lower environmental impact. Transportation-dependent systems, such as for navigation and logistics, have great potential to benefit from reliable speed estimation. While there is prior research in this area reporting competitive accuracy levels, their solutions lack reproducibility and robustness across different datasets. To address this, we provide a novel framework for automatic real-time vehicle speed calculation, which copes with more diverse data from publicly available traffic cameras to achieve greater robustness. Our model employs novel techniques to estimate the length of road segments via depth map prediction. Additionally, our framework is capable of handling realistic conditions such as camera movements and different video stream inputs automatically. We compare our model to three well-known models in the field using their benchmark datasets. While our model does not set a new state of the art regarding prediction performance, the results are competitive on realistic CCTV videos. At the same time, our end-to-end pipeline offers more consistent results, an easier implementation, and better compatibility. Its modular structure facilitates reproducibility and future improvements. △ Less

Submitted 25 September, 2023; originally announced September 2023.

ACM Class: I.4.9

Using deep learning to construct stochastic local search SAT solvers with performance bounds

Authors: Maximilian J. Kramer, Paul Boes, Jens Eisert

Abstract: The Boolean Satisfiability problem (SAT), as the prototypical $\mathsf{NP}$-complete problem, is crucial in both theoretical computer science and practical applications. To address this problem, stochastic local search (SLS) algorithms, which iteratively and randomly update candidate assignments, present an important and theoretically well-studied class of solvers. Recent theoretical advancements… ▽ More The Boolean Satisfiability problem (SAT), as the prototypical $\mathsf{NP}$-complete problem, is crucial in both theoretical computer science and practical applications. To address this problem, stochastic local search (SLS) algorithms, which iteratively and randomly update candidate assignments, present an important and theoretically well-studied class of solvers. Recent theoretical advancements have identified conditions under which SLS solvers efficiently solve SAT instances, provided they have access to suitable ``oracles'', i.e., instance-specific distribution samples. We propose leveraging machine learning models, particularly graph neural networks (GNN), as oracles to enhance the performance of SLS solvers. Our approach, evaluated on random and pseudo-industrial SAT instances, demonstrates a significant performance improvement regarding step counts and solved instances. Our work bridges theoretical results and practical applications, highlighting the potential of purpose-trained SAT solvers with performance guarantees. △ Less

Submitted 16 April, 2026; v1 submitted 20 September, 2023; originally announced September 2023.

Comments: 24 pages, significantly updated version with new datasets and experiments. Code available at https://github.com/porscheofficial/sls_sat_solving_with_deep_learning. Accepted for publication in Machine Learning: Science and Technology 7 (2026) 025057

Journal ref: Mach. Learn.: Sci. Technol. 7 (2026) 025057

Distribution and volume based scoring for Isolation Forests

Authors: Hichem Dhouib, Alissa Wilms, Paul Boes

Abstract: We make two contributions to the Isolation Forest method for anomaly and outlier detection. The first contribution is an information-theoretically motivated generalisation of the score function that is used to aggregate the scores across random tree estimators. This generalisation allows one to take into account not just the ensemble average across trees but instead the whole distribution. The sec… ▽ More We make two contributions to the Isolation Forest method for anomaly and outlier detection. The first contribution is an information-theoretically motivated generalisation of the score function that is used to aggregate the scores across random tree estimators. This generalisation allows one to take into account not just the ensemble average across trees but instead the whole distribution. The second contribution is an alternative scoring function at the level of the individual tree estimator, in which we replace the depth-based scoring of the Isolation Forest with one based on hyper-volumes associated to an isolation tree's leaf nodes. We motivate the use of both of these methods on generated data and also evaluate them on 34 datasets from the recent and exhaustive ``ADBench'' benchmark, finding significant improvement over the standard isolation forest for both variants on some datasets and improvement on average across all datasets for one of the two variants. The code to reproduce our results is made available as part of the submission. △ Less

Submitted 20 September, 2023; originally announced September 2023.

Comments: 7 pages

Polarization-dependent beam shifts upon metallic reflection in high-contrast imagers and telescopes

Authors: R. G. van Holstein, C. U. Keller, F. Snik, S. P. Bos

Abstract: (Abridged) Context. To directly image rocky exoplanets in reflected (polarized) light, future space- and ground-based high-contrast imagers and telescopes aim to reach extreme contrasts at close separations from the star. However, the achievable contrast will be limited by reflection-induced polarization aberrations. While polarization aberrations can be modeled numerically, such computations prov… ▽ More (Abridged) Context. To directly image rocky exoplanets in reflected (polarized) light, future space- and ground-based high-contrast imagers and telescopes aim to reach extreme contrasts at close separations from the star. However, the achievable contrast will be limited by reflection-induced polarization aberrations. While polarization aberrations can be modeled numerically, such computations provide little insight into the full range of effects, their origin and characteristics, and possible ways to mitigate them. Aims. We aim to understand polarization aberrations produced by reflection off flat metallic mirrors at the fundamental level. Methods. We used polarization ray tracing to numerically compute polarization aberrations and interpret the results in terms of the polarization-dependent spatial and angular Goos-Hänchen and Imbert-Federov shifts of the beam of light as described with closed-form mathematical expressions in the physics literature. Results. We find that all four beam shifts are fully reproduced by polarization ray tracing and study the origin, characteristics, sizes, and directions of the shifts. Of the four beam shifts, only the spatial Goos-Hänchen and Imbert-Federov shifts are relevant for high-contrast imagers and telescopes because these shifts are visible in the focal plane and create a polarization structure in the PSF that reduces the performance of coronagraphs and the polarimetric speckle suppression close to the star. Conclusions. The beam shifts in an optical system can be mitigated by keeping the f-numbers large and angles of incidence small. Most importantly, mirror coatings should not be optimized for maximum reflectivity, but should be designed to have a retardance close to 180°. The insights from our study can be applied to improve the performance of current and future high-contrast imagers, especially those in space and on the ELTs. △ Less

Submitted 28 September, 2023; v1 submitted 21 August, 2023; originally announced August 2023.

Comments: 19 pages, 13 figures, 1 table, final version as published in Astronomy & Astrophysics, 677, A150 (2023)

Journal ref: A&A 677, A150 (2023)

With a little help from your friends: semi-cooperative games via Joker moves

Authors: Petra van den Bos, Marielle Stoelinga

Abstract: This paper coins the notion of Joker games, a variant of concurrent games where the players are not strictly adversarial. Instead, Player 1 can get help from Player 2 by playing a Joker move. We formalize these games as cost games and develop strategies that minimize the use of Jokers - viewed as costs - to secure a win with the least possible help. Our investigation studies the theoretical underp… ▽ More This paper coins the notion of Joker games, a variant of concurrent games where the players are not strictly adversarial. Instead, Player 1 can get help from Player 2 by playing a Joker move. We formalize these games as cost games and develop strategies that minimize the use of Jokers - viewed as costs - to secure a win with the least possible help. Our investigation studies the theoretical underpinnings of these games and their associated Joker strategies. In particular, when comparing our cost-minimal strategies with admissible strategies, we find out that they differ. Moreover, while randomization can be beneficial in conventional concurrent games, it does not aid in winning Joker games, although it can help reduce the number of needed Jokers. We also enhance our framework by introducing a secondary objective, namely by minimizing the number of moves executed by a Joker strategy. Finally, we demonstrate the practical advantages of our approach by applying it to test generation in model-based testing. △ Less

Submitted 15 March, 2025; v1 submitted 26 April, 2023; originally announced April 2023.

Journal ref: Logical Methods in Computer Science, Volume 21, Issue 1 (March 18, 2025) lmcs:12944

Limits on Wave Optics Simulations of Plane Wave Propagation in Non-Kolmogorov Turbulence

Authors: Jeremy P. Bos, Stephen Grulke, Jeff Beck

Abstract: We derive limits for wave optics simulations of plane wave propagation in non-Kolmogorov turbulence using the split-step method and thin phase screens. These limits are used to inform two simulation campaigns where the relationship between volume turbulence strength and normalized intensity variance for various non-Kolmogorov power-laws. We find that simulations of smaller power laws are limited t… ▽ More We derive limits for wave optics simulations of plane wave propagation in non-Kolmogorov turbulence using the split-step method and thin phase screens. These limits are used to inform two simulation campaigns where the relationship between volume turbulence strength and normalized intensity variance for various non-Kolmogorov power-laws. We find that simulations of smaller power laws are limited turbulence strengths with Rytov numbers of 7 when the simulation side-length sampling rate is 8192. Under these same conditions it is possible to simulate volume turbulence strength out to Rytov numbers of 12 for Kolmogorov power-laws and higher. We show that the peak scintillation and Rytov number where peak scintillation occur increases monotonically with power-law. Also, that if turbulence strength is fixed, the relationship between scintillation index and power-law depends on the operating regime. In weak turbulence the relationship is negative, and it is positive in stronger turbulence. This work also emphasizes the importance of properly scaling turbulence strength with comparing results with different power-laws and the influence and importance of defining inner and outer scales in these simulations. △ Less

Submitted 7 August, 2022; originally announced August 2022.

Transparent reporting of research-related greenhouse gas emissions through the scientific CO$_2$nduct initiative

Authors: Ryan Sweke, Paul Boes, Nelly H. Y. Ng, Carlo Sparaciari, Jens Eisert, Marcel Goihl

Abstract: Estimating the greenhouse gas emissions of research-related activities is a critical first step towards the design of mitigation policies and actions. Here we propose and motivate a transparent framework for reporting research-related greenhouse gas emissions, through the inclusion of standardised reporting tables in scientific publications. Estimating the greenhouse gas emissions of research-related activities is a critical first step towards the design of mitigation policies and actions. Here we propose and motivate a transparent framework for reporting research-related greenhouse gas emissions, through the inclusion of standardised reporting tables in scientific publications. △ Less

Submitted 1 June, 2022; originally announced June 2022.

Journal ref: Commun. Phys. 5, 150 (2022)

High contrast imaging at the photon noise limit with self-calibrating WFS/C systems

Authors: Olivier Guyon, Barnaby Norris, Marc-Antoine Martinod, Kyohoon Ahn, Peter Tuthill, Jared Males, Alison Wong, Nour Skaf, Thayne Currie, Kelsey Miller, Steven P. Bos, Julien Lozi, Vincent Deo, Sebastien Vievard, Ruslan Belikov, Kyle van Gorkom, Benjamin Mazin, Michael Bottom, Richard Frazin, Alexander Rodack, Tyler Groff, Nemanja Jovanovic, Frantz Martinache

Abstract: High contrast imaging (HCI) systems rely on active wavefront control (WFC) to deliver deep raw contrast in the focal plane, and on calibration techniques to further enhance contrast by identifying planet light within the residual speckle halo. Both functions can be combined in an HCI system and we discuss a path toward designing HCI systems capable of calibrating residual starlight at the fundamen… ▽ More High contrast imaging (HCI) systems rely on active wavefront control (WFC) to deliver deep raw contrast in the focal plane, and on calibration techniques to further enhance contrast by identifying planet light within the residual speckle halo. Both functions can be combined in an HCI system and we discuss a path toward designing HCI systems capable of calibrating residual starlight at the fundamental contrast limit imposed by photon noise. We highlight the value of deploying multiple high-efficiency wavefront sensors (WFSs) covering a wide spectral range and spanning multiple optical locations. We show how their combined information can be leveraged to simultaneously improve WFS sensitivity and residual starlight calibration, ideally making it impossible for an image plane speckle to hide from WFS telemetry. We demonstrate residual starlight calibration in the laboratory and on-sky, using both a coronagraphic setup, and a nulling spectro-interferometer. In both case, we show that bright starlight can calibrate residual starlight. △ Less

Submitted 4 October, 2021; v1 submitted 28 September, 2021; originally announced September 2021.

Comments: 11 pages, 6 Figures, 1 Table; Proc. SPIE in press

SCExAO, a testbed for developing high-contrast imaging technologies for ELTs

Authors: Kyohoon Ahn, Olivier Guyon, Julien Lozi, Sébastien Vievard, Vincent Deo, Nour Skaf, Ruslan Belikov, Steven P. Bos, Michael Bottom, Thayne Currie, Richard Frazin, Kyle V. Gorkom, Tyler D. Groff, Sebastiaan Y. Haffert, Nemanja Jovanovic, Hajime Kawahara, Takayuki Kotani, Jared R. Males, Frantz Martinache, Benjamin A. Mazin, Kelsey Miller, Barnaby Norris, Alexander Rodack, Alison Wong

Abstract: To directly detect exoplanets and protoplanetary disks, the development of high accuracy wavefront sensing and control (WFS&C) technologies is essential, especially for ground-based Extremely Large Telescopes (ELTs). The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument is a high-contrast imaging platform to discover and characterize exoplanets and protoplanetary disks. It also serv… ▽ More To directly detect exoplanets and protoplanetary disks, the development of high accuracy wavefront sensing and control (WFS&C) technologies is essential, especially for ground-based Extremely Large Telescopes (ELTs). The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument is a high-contrast imaging platform to discover and characterize exoplanets and protoplanetary disks. It also serves as a testbed to validate and deploy new concepts or algorithms for high-contrast imaging approaches for ELTs, using the latest hardware and software technologies on an 8-meter class telescope. SCExAO is a multi-band instrument, using light from 600 to 2500 nm, and delivering a high Strehl ratio (>80% in median seeing in H-band) downstream of a low-order correction provided by the facility AO188. Science observations are performed with coronagraphs, an integral field spectrograph, or single aperture interferometers. The SCExAO project continuously reaches out to the community for development and upgrades. Existing operating testbeds such as the SCExAO are also unique opportunities to test and deploy the new technologies for future ELTs. We present and show a live demonstration of the SCExAO capabilities (Real-time predictive AO control, Focal plane WFS&C, etc) as a host testbed for the remote collaborators to test and deploy the new WFS&C concepts or algorithms. We also present several high-contrast imaging technologies that are under development or that have already been demonstrated on-sky. △ Less

Submitted 28 September, 2021; v1 submitted 27 September, 2021; originally announced September 2021.

Comments: 13 pages, 8 figures, 2021 SPIE Optics+Photonics

Full characterization of the instrumental polarization effects of the spectropolarimetric mode of SCExAO-CHARIS

Authors: G. J. Joost `t Hart, Rob G. van Holstein, Steven P. Bos, Jasper Ruigrok, Frans Snik, Julien Lozi, Olivier Guyon, Tomoyuki Kudo, Jin Zhang, Nemanja Jovanovic, Barnaby Norris, Marc-Antoine Martinod, Tyler D. Groff, Jeffrey Chilcote, Thayne Currie, Motohide Tamura, Sébastien Vievard, Ananya Sahoo, Vincent Deo, Kyohoon Ahn, Frantz Martinache, Jeremy Kasdin

Abstract: SCExAO at the Subaru telescope is a visible and near-infrared high-contrast imaging instrument employing extreme adaptive optics and coronagraphy. The instrument feeds the near-infrared light (JHK) to the integral-field spectrograph CHARIS. The spectropolarimetric capability of CHARIS is enabled by a Wollaston prism and is unique among high-contrast imagers. We present a detailed Mueller matrix mo… ▽ More SCExAO at the Subaru telescope is a visible and near-infrared high-contrast imaging instrument employing extreme adaptive optics and coronagraphy. The instrument feeds the near-infrared light (JHK) to the integral-field spectrograph CHARIS. The spectropolarimetric capability of CHARIS is enabled by a Wollaston prism and is unique among high-contrast imagers. We present a detailed Mueller matrix model describing the instrumental polarization effects of the complete optical path, thus the telescope and instrument. From measurements with the internal light source, we find that the image derotator (K-mirror) produces strongly wavelength-dependent crosstalk, in the worst case converting ~95% of the incident linear polarization to circularly polarized light that cannot be measured. Observations of an unpolarized star show that the magnitude of the instrumental polarization of the telescope varies with wavelength between 0.5% and 1%, and that its angle is exactly equal to the altitude angle of the telescope. Using physical models of the fold mirror of the telescope, the half-wave plate, and the derotator, we simultaneously fit the instrumental polarization effects in the 22 wavelength bins. Over the full wavelength range, our model currently reaches a total polarimetric accuracy between 0.08% and 0.24% in the degree of linear polarization. We propose additional calibration measurements to improve the polarimetric accuracy to <0.1% and plan to integrate the complete Mueller matrix model into the existing CHARIS post-processing pipeline. Our calibrations of CHARIS' spectropolarimetric mode will enable unique quantitative polarimetric studies of circumstellar disks and planetary and brown dwarf companions. △ Less

Submitted 10 August, 2021; originally announced August 2021.

Comments: 27 pages, 16 figures, submitted to SPIE Optics + Photonics 2021

"Fast" and Furious focal-plane wavefront sensing at W. M. Keck Observatory

Authors: Steven P. Bos, Michael Bottom, Sam Ragland, Jacques-Robert Delorme, Sylvain Cetre, Laurent Pueyo

Abstract: High quality, repeatable point-spread functions are important for science cases like direct exoplanet imaging, high-precision astrometry, and high-resolution spectroscopy of exoplanets. For such demanding applications, the initial on-sky point-spread function delivered by the adaptive optics system can require further optimization to correct unsensed static aberrations and calibration biases. We i… ▽ More High quality, repeatable point-spread functions are important for science cases like direct exoplanet imaging, high-precision astrometry, and high-resolution spectroscopy of exoplanets. For such demanding applications, the initial on-sky point-spread function delivered by the adaptive optics system can require further optimization to correct unsensed static aberrations and calibration biases. We investigated using the Fast and Furious focal-plane wavefront sensing algorithm as a potential solution. This algorithm uses a simple model of the optical system and focal plane information to measure and correct the point-spread function phase, without using defocused images, meaning it can run concurrently with science. On-sky testing demonstrated significantly improved PSF quality in only a few iterations, with both narrow and broadband filters. These results suggest this algorithm is a useful path forward for creating and maintaining high-quality, repeatable on-sky adaptive optics point-spread functions. △ Less

Submitted 15 July, 2021; originally announced July 2021.

Comments: 12 pages, 9 figures, to appear in SPIE Optics+Photonics 2021

First on-sky demonstration of spatial Linear Dark Field Control with the vector-Apodizing Phase Plate at Subaru/SCExAO

Authors: S. P. Bos, K. L. Miller, J. Lozi, O. Guyon, D. S. Doelman, S. Vievard, A. Sahoo, V. Deo, N. Jovanovic, F. Martinache, T. Currie, F. Snik

Abstract: One of the key noise sources that currently limits high-contrast imaging observations for exoplanet detection is quasi-static speckles. Quasi-static speckles originate from slowly evolving non-common path aberrations (NCPA). The purpose of this work is to present a proof-of-concept on-sky demonstration of spatial Linear Dark Field Control (LDFC). The ultimate goal of LDFC is to stabilize the point… ▽ More One of the key noise sources that currently limits high-contrast imaging observations for exoplanet detection is quasi-static speckles. Quasi-static speckles originate from slowly evolving non-common path aberrations (NCPA). The purpose of this work is to present a proof-of-concept on-sky demonstration of spatial Linear Dark Field Control (LDFC). The ultimate goal of LDFC is to stabilize the point spread function (PSF) by addressing NCPA using the science image as additional wavefront sensor. We combined spatial LDFC with the Asymmetric Pupil vector-Apodizing Phase Plate (APvAPP) on the Subaru Coronagraphic Extreme Adaptive Optics system at the Subaru Telescope. In this paper, we report the results of the first successful proof-of-principle LDFC on-sky tests. We present results from two types of cases: (1) correction of instrumental errors and atmospheric residuals plus artificially induced static aberrations introduced on the deformable mirror and (2) correction of only atmospheric residuals and instrumental aberrations. When introducing artificial static wavefront aberrations on the DM, we find that LDFC can improve the raw contrast by a factor of $3$--$7$ over the dark hole. In these tests, the residual wavefront error decreased by $\sim$50 nm RMS, from $\sim$90 nm to $\sim40$ nm RMS. In the case with only residual atmospheric wavefront errors and instrumental aberrations, we show that LDFC is able to suppress evolving aberrations that have timescales of $<0.1$--$0.4$ Hz. We find that the power at $10^{-2}$ Hz is reduced by a factor of $\sim$20, 7, and 4 for spatial frequency bins at 2.5, 5.5, and 8.5 $λ/D$, respectively. The results presented in this work show that LDFC is a promising technique for enabling the high-contrast imaging goals of the upcoming generation of extremely large telescopes. △ Less

Submitted 11 June, 2021; originally announced June 2021.

Comments: Accepted for publication in Astronomy&Astrophysics. 13 pages, 11 figures, 2 tables

Journal ref: A&A 653, A42 (2021)

The vector-apodizing phase plate coronagraph: design, current performance, and future development

Authors: D. S. Doelman, F. Snik, E. H. Por, S. P. Bos, G. P. P. L. Otten, M. Kenworthy, S. Y. Haffert, M. Wilby, A. J. Bohn, B. J. Sutlieff, K. Miller, M. Ouellet, J. de Boer, C. U. Keller, M. J. Escuti, S. Shi, N. Z. Warriner, K. J. Hornburg, J. L. Birkby, J. Males, K. M. Morzinski, L. M. Close, J. Codona, J. Long, L. Schatz , et al. (28 additional authors not shown)

Abstract: Over the last decade, the vector-apodizing phase plate (vAPP) coronagraph has been developed from concept to on-sky application in many high-contrast imaging systems on 8-m class telescopes. The vAPP is an geometric-phase patterned coronagraph that is inherently broadband, and its manufacturing is enabled only by direct-write technology for liquid-crystal patterns. The vAPP generates two coronagra… ▽ More Over the last decade, the vector-apodizing phase plate (vAPP) coronagraph has been developed from concept to on-sky application in many high-contrast imaging systems on 8-m class telescopes. The vAPP is an geometric-phase patterned coronagraph that is inherently broadband, and its manufacturing is enabled only by direct-write technology for liquid-crystal patterns. The vAPP generates two coronagraphic PSFs that cancel starlight on opposite sides of the point spread function (PSF) and have opposite circular polarization states. The efficiency, that is the amount of light in these PSFs, depends on the retardance offset from half-wave of the liquid-crystal retarder. Using different liquid-crystal recipes to tune the retardance, different vAPPs operate with high efficiencies ($>96\%$) in the visible and thermal infrared (0.55 $μ$m to 5 $μ$m). Since 2015, seven vAPPs have been installed in a total of six different instruments, including Magellan/MagAO, Magellan/MagAO-X, Subaru/SCExAO, and LBT/LMIRcam. Using two integral field spectrographs installed on the latter two instruments, these vAPPs can provide low-resolution spectra (R$\sim$30) between 1 $μ$m and 5 $μ$m. We review the design process, development, commissioning, on-sky performance, and first scientific results of all commissioned vAPPs. We report on the lessons learned and conclude with perspectives for future developments and applications. △ Less

Submitted 4 November, 2021; v1 submitted 22 April, 2021; originally announced April 2021.

Comments: 38 pages, 17 figures, accepted for publication in Applied Optics, added NSF grant acknowledgement

Machine learning method for light field refocusing

Authors: Eisa Hedayati, Timothy C. Havens, Jeremy P. Bos

Abstract: Light field imaging introduced the capability to refocus an image after capturing. Currently there are two popular methods for refocusing, shift-and-sum and Fourier slice methods. Neither of these two methods can refocus the light field in real-time without any pre-processing. In this paper we introduce a machine learning based refocusing technique that is capable of extracting 16 refocused images… ▽ More Light field imaging introduced the capability to refocus an image after capturing. Currently there are two popular methods for refocusing, shift-and-sum and Fourier slice methods. Neither of these two methods can refocus the light field in real-time without any pre-processing. In this paper we introduce a machine learning based refocusing technique that is capable of extracting 16 refocused images with refocusing parameters of α=0.125,0.250,0.375,...,2.0 in real-time. We have trained our network, which is called RefNet, in two experiments. Once using the Fourier slice method as the training -- i.e., "ground truth" -- data and another using the shift-and-sum method as the training data. We showed that in both cases, not only is the RefNet method at least 134x faster than previous approaches, but also the color prediction of RefNet is superior to both Fourier slice and shift-and-sum methods while having similar depth of field and focus distance performance. △ Less

Submitted 18 April, 2022; v1 submitted 29 March, 2021; originally announced March 2021.

The polarization-encoded self-coherent camera

Authors: Steven P. Bos

Abstract: The exploration of circumstellar environments by means of direct imaging to search for Earth-like exoplanets is one of the challenges of modern astronomy. One of the current limitations are evolving non-common path aberrations (NCPA) that originate from optics downstream of the main wavefront sensor. The self-coherent camera (SCC) is an integrated coronagraph and focal-plane wavefront sensor that… ▽ More The exploration of circumstellar environments by means of direct imaging to search for Earth-like exoplanets is one of the challenges of modern astronomy. One of the current limitations are evolving non-common path aberrations (NCPA) that originate from optics downstream of the main wavefront sensor. The self-coherent camera (SCC) is an integrated coronagraph and focal-plane wavefront sensor that generates wavefront information-encoding Fizeau fringes in the focal plane by adding a reference hole (RH) in the Lyot stop. Here, we aim to show that by featuring a polarizer in the RH and adding a polarizing beamsplitter downstream of the Lyot stop, the RH can be placed right next to the pupil. We refer to this new variant of the SCC as the polarization-encoded self-coherent camera (PESCC). We study the performance of the PESCC analytically and numerically, and compare it, where relevant, to the SCC. We show analytically that the PESCC relaxes the requirements on the focal-plane sampling and spectral resolution with respect to the SCC by a factor of 2 and 3.5, respectively. Furthermore, we find via our numerical simulations that the PESCC has effectively access to $\sim$16 times more photons, which improves the sensitivity of the wavefront sensing by a factor of $\sim4$. We also show that without additional measurements, the RH point-spread function (PSF) can be calibrated using PESCC images, enabling coherent differential imaging (CDI) as a contrast-enhancing post-processing technique for every observation. In idealized simulations (clear aperture, charge two vortex coronagraph, perfect DM, no noise sources other than phase and amplitude aberrations) and in circumstances similar to those of space-based systems, we show that WFSC combined with CDI can achieve a $1σ$ raw contrast of $\sim3\cdot10^{-11}- 8 \cdot 10^{-11}$ between 1 and 18 $λ/ D$. △ Less

Submitted 8 January, 2021; originally announced January 2021.

Comments: Accepted for publication in A&A. Shortened abstract. 17 pages, 21 figures

Journal ref: A&A 646, A177 (2021)

Focal Plane Wavefront Sensing on SUBARU/SCExAO

Authors: Sebastien Vievard, Steven P. Bos, Frederic Cassaing, Thayne Currie, Vincent Deo, Olivier Guyon, Nemanja Jovanovic, Christoph Keller, Masen Lamb, Coline Lopez, Julien Lozi, Frantz Martinache, Kelsey Miller, Aurelie Montmerle-Bonnefois, Laurent M. Mugnier, Mamadou N'Diaye, Barnaby Norris, Ananya Sahoo, Jean-François Sauvage, Nour Skaf, Frans Snik, Michael J. Wilby, Alisson Wong

Abstract: Focal plane wavefront sensing is an elegant solution for wavefront sensing since near-focal images of any source taken by a detector show distortions in the presence of aberrations. Non-Common Path Aberrations and the Low Wind Effect both have the ability to limit the achievable contrast of the finest coronagraphs coupled with the best extreme adaptive optics systems. To correct for these aberrati… ▽ More Focal plane wavefront sensing is an elegant solution for wavefront sensing since near-focal images of any source taken by a detector show distortions in the presence of aberrations. Non-Common Path Aberrations and the Low Wind Effect both have the ability to limit the achievable contrast of the finest coronagraphs coupled with the best extreme adaptive optics systems. To correct for these aberrations, the Subaru Coronagraphic Extreme Adaptive Optics instrument hosts many focal plane wavefront sensors using detectors as close to the science detector as possible. We present seven of them and compare their implementation and efficiency on SCExAO. This work will be critical for wavefront sensing on next generation of extremely large telescopes that might present similar limitations. △ Less

Submitted 22 December, 2020; originally announced December 2020.

Comments: SPIE proceeding : Astronomical Telescopes + Instrumentation 2020. arXiv admin note: text overlap with arXiv:1912.10179

Calibration of the instrumental polarization effects of SCExAO-CHARIS' spectropolarimetric mode

Authors: Rob G. van Holstein, Steven P. Bos, Jasper Ruigrok, Julien Lozi, Olivier Guyon, Barnaby Norris, Frans Snik, Jeffrey Chilcote, Thayne Currie, Tyler D. Groff, Joost 't Hart, Nemanja Jovanovic, Jeremy Kasdin, Tomoyuki Kudo, Frantz Martinache, Ben Mazin, Ananya Sahoo, Motohide Tamura, Sébastien Vievard, Alex Walter, Jin Zhang

Abstract: SCExAO at the Subaru telescope is a visible and near-infrared high-contrast imaging instrument employing extreme adaptive optics and coronagraphy. The instrument feeds the near-infrared light (JHK) to the integral field spectrograph CHARIS. Recently, a Wollaston prism was added to CHARIS' optical path, giving CHARIS a spectropolarimetric capability that is unique among high-contrast imaging instru… ▽ More SCExAO at the Subaru telescope is a visible and near-infrared high-contrast imaging instrument employing extreme adaptive optics and coronagraphy. The instrument feeds the near-infrared light (JHK) to the integral field spectrograph CHARIS. Recently, a Wollaston prism was added to CHARIS' optical path, giving CHARIS a spectropolarimetric capability that is unique among high-contrast imaging instruments. We present a detailed Mueller matrix model describing the instrumental polarization effects of the complete optical path, thus the telescope and instrument. The 22 wavelength bins of CHARIS provide a unique opportunity to investigate in detail the wavelength dependence of the instrumental polarization effects. From measurements with the internal light source, we find that the image derotator (K-mirror) produces strong wavelength-dependent crosstalk, in the worst case converting ~95% of the incident linear polarization to circularly polarized light that cannot be measured. Theoretical calculations show that the magnitude of the instrumental polarization of the telescope varies with wavelength between approximately 0.5% and 0.7%, and that its angle is exactly equal to the altitude angle of the telescope. We plan to more accurately determine the instrumental polarization of the telescope with observations of a polarization standard star, and fit more comprehensive physical models to all experimental data. In addition, we plan to integrate the complete Mueller matrix model into the existing CHARIS post-processing pipeline, with the aim to achieve a polarimetric accuracy of <0.1% in the degree of linear polarization. Our calibrations of CHARIS' spectropolarimetric mode will enable unique quantitative polarimetric studies of circumstellar disks and planetary and brown dwarf companions. △ Less

Submitted 1 December, 2020; originally announced December 2020.

Comments: 14 pages, 7 figures, submitted to SPIE Astronomical Telescopes + Instrumentation 2020

New concepts in vector-Apodizing Phase Plate coronagraphy

Authors: Steven P. Bos, David S. Doelman, Kelsey L. Miller, Frans Snik

Abstract: The vector-Apodizing Phase Plate (vAPP) is a pupil-plane coronagraph that manipulates phase to create dark holes in the stellar PSF. The phase is induced on the circular polarization states through the inherently achromatic geometric phase by spatially varying the fast axis orientation of a half-wave liquid-crystal layer. The two polarized PSFs can be separated, either by a quarter-wave plate (QWP… ▽ More The vector-Apodizing Phase Plate (vAPP) is a pupil-plane coronagraph that manipulates phase to create dark holes in the stellar PSF. The phase is induced on the circular polarization states through the inherently achromatic geometric phase by spatially varying the fast axis orientation of a half-wave liquid-crystal layer. The two polarized PSFs can be separated, either by a quarter-wave plate (QWP) followed by a polarizing beamsplitter (PBS) for broadband operation, or a polarization sensitive grating (PSG) for narrowband or IFS operation. Here we present new vAPP concepts that lift the restrictions of previous designs and report on their performance. We demonstrated that the QWP+PBS combination puts tight tolerances on the components to prevent leakage of non-coronagraphic light into the dark-hole. We present a new broadband design using an innovative two-stage patterned liquid-crystal element system based on multi-color holography, alleviating the leakage problem and relaxing manufacturing tolerances. Furthermore, we have shown that focal-plane wavefront sensing (FPWFS) can be integrated into the vAPP by an asymmetric pupil. However, such vAPPs suffer from a reduced throughput and have only been demonstrated with a PSG in narrowband operation. We present advanced designs that maintain throughput and enable phase and amplitude wavefront sensing. We also present broadband vAPP FPWFS designs and outline a broadband FPWFS algorithm. Finally, previous dual-beam vAPP designs for sensitive polarimetry with one-sided dark holes were very complex. We show new dual-beam designs that significantly reduce the complexity. △ Less

Submitted 7 January, 2021; v1 submitted 1 December, 2020; originally announced December 2020.

Comments: 13 pages, 15 figures, published in SPIE. Re-uploaded to fix a corrupted figure

The generalised Hausdorff measure of sets of Dirichlet non-improvable numbers

Authors: Philip Bos, Mumtaz Hussain, David Simmons

Abstract: Let $ψ:\mathbb R_+\to\mathbb R_+$ be a non-increasing function. A real number $x$ is said to be $ψ$-Dirichlet improvable if the system $$|qx-p|< \, ψ(t) \ \ {\text{and}} \ \ |q|<t$$ has a non-trivial integer solution for all large enough $t$. Denote the collection of such points by $D(ψ)$. In this paper, we prove a zero-infinity law valid for all dimension functions under natural non-restrictive c… ▽ More Let $ψ:\mathbb R_+\to\mathbb R_+$ be a non-increasing function. A real number $x$ is said to be $ψ$-Dirichlet improvable if the system $$|qx-p|< \, ψ(t) \ \ {\text{and}} \ \ |q|<t$$ has a non-trivial integer solution for all large enough $t$. Denote the collection of such points by $D(ψ)$. In this paper, we prove a zero-infinity law valid for all dimension functions under natural non-restrictive conditions. Some of the consequences are zero-infinity laws, for all essentially sub-linear dimension functions proved by Hussain-Kleinbock-Wadleigh-Wang (2018), for some non-essentially sub-linear dimension functions, and for all dimension functions but with a growth condition on the approximating function. △ Less

Submitted 18 August, 2022; v1 submitted 26 October, 2020; originally announced October 2020.

Comments: In Press: Proceedings of the American Mathematical Society. arXiv admin note: text overlap with arXiv:1704.03089

MSC Class: 11J83; 11K60; 28A78; 11K50; 11K55; 11A55

Light Field Compression by Residual CNN Assisted JPEG

Authors: Eisa Hedayati, Timothy C. Havens, Jeremy P. Bos

Abstract: Light field (LF) imaging has gained significant attention due to its recent success in 3-dimensional (3D) displaying and rendering as well as augmented and virtual reality usage. Nonetheless, because of the two extra dimensions, LFs are much larger than conventional images. We develop a JPEG-assisted learning-based technique to reconstruct an LF from a JPEG bitstream with a bit per pixel ratio of… ▽ More Light field (LF) imaging has gained significant attention due to its recent success in 3-dimensional (3D) displaying and rendering as well as augmented and virtual reality usage. Nonetheless, because of the two extra dimensions, LFs are much larger than conventional images. We develop a JPEG-assisted learning-based technique to reconstruct an LF from a JPEG bitstream with a bit per pixel ratio of 0.0047 on average. For compression, we keep the LF's center view and use JPEG compression with 50% quality. Our reconstruction pipeline consists of a small JPEG enhancement network (JPEG-Hance), a depth estimation network (Depth-Net), followed by view synthesizing by warping the enhanced center view. Our pipeline is significantly faster than using video compression on pseudo-sequences extracted from an LF, both in compression and decompression, while maintaining effective performance. We show that with a 1% compression time cost and 18x speedup for decompression, our methods reconstructed LFs have better structural similarity index metric (SSIM) and comparable peak signal-to-noise ratio (PSNR) compared to the state-of-the-art video compression techniques used to compress LFs. △ Less

Submitted 18 March, 2021; v1 submitted 30 September, 2020; originally announced October 2020.

Journal ref: 2021 International Joint Conference on Neural Networks (IJCNN), 2021, pp. 1-9

The variance of relative surprisal as single-shot quantifier

Authors: Paul Boes, Nelly H. Y. Ng, Henrik Wilming

Abstract: The variance of (relative) surprisal, also known as varentropy, so far mostly plays a role in information theory as quantifying the leading order corrections to asymptotic i.i.d.~limits. Here, we comprehensively study the use of it to derive single-shot results in (quantum) information theory. We show that it gives genuine sufficient and necessary conditions for approximate state-transitions betwe… ▽ More The variance of (relative) surprisal, also known as varentropy, so far mostly plays a role in information theory as quantifying the leading order corrections to asymptotic i.i.d.~limits. Here, we comprehensively study the use of it to derive single-shot results in (quantum) information theory. We show that it gives genuine sufficient and necessary conditions for approximate state-transitions between pairs of quantum states in the single-shot setting, without the need for further optimization. We also clarify its relation to smoothed min- and max-entropies, and construct a monotone for resource theories using only the standard (relative) entropy and variance of (relative) surprisal. This immediately gives rise to enhanced lower bounds for entropy production in random processes. We establish certain properties of the variance of relative surprisal which will be useful for further investigations, such as uniform continuity and upper bounds on the violation of sub-additivity. Motivated by our results, we further derive a simple and physically appealing axiomatic single-shot characterization of (relative) entropy which we believe to be of independent interest. We illustrate our results with several applications, ranging from interconvertibility of ergodic states, over Landauer erasure to a bound on the necessary dimension of the catalyst for catalytic state transitions and Boltzmann's H-theorem. △ Less

Submitted 29 March, 2022; v1 submitted 17 September, 2020; originally announced September 2020.

Comments: v3: published version

Journal ref: PRX Quantum 3, 010325, 2022

Detection of polarization neutral points in observations of the combined corona and sky during the 21 August 2017 total solar eclipse

Authors: Frans Snik, Steven P. Bos, Stefanie A. Brackenhoff, David S. Doelman, Emiel H. Por, Felix Bettonvil, Michiel Rodenhuis, Dmitry Vorobiev, Laura M. Eshelman, Joseph A. Shaw

Abstract: We report the results of polarimetric observations of the total solar eclipse of 21 August 2017 from Rexburg, Idaho (USA). We use three synchronized DSLR cameras with polarization filters oriented at 0°, 60°, and 120° to provide high-dynamic-range RGB polarization images of the corona and surrounding sky. We measure tangential coronal polarization and vertical sky polarization, both as expected. T… ▽ More We report the results of polarimetric observations of the total solar eclipse of 21 August 2017 from Rexburg, Idaho (USA). We use three synchronized DSLR cameras with polarization filters oriented at 0°, 60°, and 120° to provide high-dynamic-range RGB polarization images of the corona and surrounding sky. We measure tangential coronal polarization and vertical sky polarization, both as expected. These observations provide detailed detections of polarization neutral points above and below the eclipsed Sun where the coronal polarization is canceled by the sky polarization. We name these special polarization neutral points after Minnaert and Van de Hulst. △ Less

Submitted 23 July, 2020; originally announced July 2020.

Comments: Part of the Applied Optics special feature issue on Light and Color in Nature

Journal ref: Applied Optics Vol. 59, Issue 21, pp. F71-F77 (2020)

On-sky verification of Fast and Furious focal-plane wavefront sensing: Moving forward toward controlling the island effect at Subaru/SCExAO

Authors: Steven P. Bos, Sébastien Vievard, Michael J. Wilby, Frans Snik, Julien Lozi, Olivier Guyon, Barnaby R. M. Norris, Nemanja Jovanovic, Frantz Martinache, Jean-François Sauvage, Christoph U. Keller

Abstract: High-contrast imaging (HCI) observations of exoplanets can be limited by the island effect (IE). On the current generation of telescopes, the IE becomes a severe problem when the ground wind speed is below a few meters per second. This is referred to as the low-wind effect (LWE). The LWE severely distorts the point spread function (PSF), significantly lowering the Strehl ratio and degrading the co… ▽ More High-contrast imaging (HCI) observations of exoplanets can be limited by the island effect (IE). On the current generation of telescopes, the IE becomes a severe problem when the ground wind speed is below a few meters per second. This is referred to as the low-wind effect (LWE). The LWE severely distorts the point spread function (PSF), significantly lowering the Strehl ratio and degrading the contrast. In this article, we aim to show that the focal-plane wavefront sensing (FPWFS) algorithm, Fast and Furious (F&F), can be used to measure and correct the IE/LWE. We deployed the algorithm on the SCExAO HCI instrument at the Subaru Telescope using the internal near-infrared camera in H-band. We tested F&F with the internal source, and it was deployed on-sky to test its performance with the full end-to-end system and atmospheric turbulence. The performance of the algorithm was evaluated by two metrics based on the PSF quality: 1) the Strehl ratio approximation ($SRA$), and 2) variance of the normalized first Airy ring ($VAR$). Random LWE phase screens with a peak-to-valley wavefront error between 0.4 $μ$m and 2 $μ$m were all corrected to a $SRA$ $>$90\% and an $VAR\lessapprox0.05$. Furthermore, the on-sky results show that F&F is able to improve the PSF quality during very challenging atmospheric conditions (1.3-1.4'' seeing at 500 nm). Closed-loop tests show that F&F is able to improve the $VAR$ from 0.27 to 0.03 and therefore significantly improve the symmetry of the PSF. Simultaneous observations of the PSF in the {optical} ($λ= $ 750 nm, $Δλ=$ 50 nm) show that during these tests we were correcting aberrations common to the optical and NIR paths within SCExAO. Going forward, the algorithm is suitable for incorporation into observing modes, which will enable PSFs of higher quality and stability during science observations. △ Less

Submitted 25 May, 2020; originally announced May 2020.

Comments: Accepted for publication in A&A. Abstract shortened for arXiv

Journal ref: A&A 639, A52 (2020)

Vector speckle grid: instantaneous incoherent speckle grid for high-precision astrometry and photometry in high-contrast imaging

Authors: Steven P. Bos

Abstract: Photometric and astrometric monitoring of directly imaged exoplanets will deliver unique insights into their rotational periods, the distribution of cloud structures, weather, and orbital parameters. As the host star is occulted by the coronagraph, a speckle grid (SG) is introduced to serve as astrometric and photometric reference. Speckle grids are implemented as diffractive pupil-plane optics th… ▽ More Photometric and astrometric monitoring of directly imaged exoplanets will deliver unique insights into their rotational periods, the distribution of cloud structures, weather, and orbital parameters. As the host star is occulted by the coronagraph, a speckle grid (SG) is introduced to serve as astrometric and photometric reference. Speckle grids are implemented as diffractive pupil-plane optics that generate artificial speckles at known location and brightness. Their performance is limited by the underlying speckle halo caused by evolving uncorrected wavefront errors. The speckle halo will interfere with the coherent SGs, affecting their photometric and astrometric precision. Our aim is to show that by imposing opposite amplitude or phase modulation on the opposite polarization states, a SG can be instantaneously incoherent with the underlying halo, greatly increasing the precision. We refer to these as vector speckle grids (VSGs). We derive analytically the mechanism by which the incoherency arises and explore the performance gain in idealised simulations under various atmospheric conditions. We show that the VSG is completely incoherent for unpolarized light and that the fundamental limiting factor is the cross-talk between the speckles in the grid. In simulation, we find that for short-exposure images the VSG reaches a $\sim$0.3-0.8\% photometric error and $\sim$$3-10\cdot10^{-3}$ $λ/D$ astrometric error, which is a performance increase of a factor $\sim$20 and $\sim$5, respectively. Furthermore, we outline how VSGs could be implemented using liquid-crystal technology to impose the geometric phase on the circular polarization states. The VSG is a promising new method for generating a photometric and astrometric reference SG that has a greatly increased astrometric and photometric precision. △ Less

Submitted 18 May, 2020; originally announced May 2020.

Comments: Accepted for publication in A&A

Journal ref: A&A 638, A118 (2020)

Bounding the resources for thermalizing many-body localized systems

Authors: Carlo Sparaciari, Marcel Goihl, Paul Boes, Jens Eisert, Nelly Huei Ying Ng

Abstract: Understanding under which conditions physical systems thermalize is a long-standing question in many-body physics. While generic quantum systems thermalize, there are known instances where thermalization is hindered, for example in many-body localized (MBL) systems. Here we introduce a class of stochastic collision models coupling a many-body system out of thermal equilibrium to an external heat b… ▽ More Understanding under which conditions physical systems thermalize is a long-standing question in many-body physics. While generic quantum systems thermalize, there are known instances where thermalization is hindered, for example in many-body localized (MBL) systems. Here we introduce a class of stochastic collision models coupling a many-body system out of thermal equilibrium to an external heat bath. We derive upper and lower bounds on the size of the bath required to thermalize the system via such models, under certain assumptions on the Hamiltonian. We use these bounds, expressed in terms of the max-relative entropy, to characterize the robustness of MBL systems against externally-induced thermalization. Our bounds are derived within the framework of resource theories using the convex split lemma, a recent tool developed in quantum information. We apply our results to the disordered Heisenberg chain, and numerically study the robustness of its MBL phase in terms of the required bath size. △ Less

Submitted 7 January, 2021; v1 submitted 10 December, 2019; originally announced December 2019.

Comments: 8+13 pages, comments welcomed

Journal ref: Comm. Phys. 4, 3 (2021)

Focal-plane wavefront sensing with the vector Apodizing Phase Plate

Authors: Steven P. Bos, David S. Doelman, Julien Lozi, Olivier Guyon, Christoph U. Keller, Kelsey L. Miller, Nemanja Jovanovic, Frantz Martinache, Frans Snik

Abstract: In this article we show that the vector-Apodizing Phase Plate (vAPP) coronagraph can be designed such that the coronagraphic point spread functions (PSFs) can act as a wavefront sensor to measure and correct the (quasi-)static aberrations, without dedicated wavefront sensing holograms nor modulation by the deformable mirror. The absolute wavefront retrieval is performed with a non-linear algorithm… ▽ More In this article we show that the vector-Apodizing Phase Plate (vAPP) coronagraph can be designed such that the coronagraphic point spread functions (PSFs) can act as a wavefront sensor to measure and correct the (quasi-)static aberrations, without dedicated wavefront sensing holograms nor modulation by the deformable mirror. The absolute wavefront retrieval is performed with a non-linear algorithm. The focal-plane wavefront sensing (FPWFS) performance of the vAPP and the algorithm are evaluated with numerical simulations, to test various photon and read noise levels, the sensitivity to the 100 lowest Zernike modes and the maximum wavefront error (WFE) that can be accurately estimated in one iteration. We apply these methods to the vAPP within SCExAO, first with the internal source and subsequently on-sky. In idealised simulations we show that for $10^7$ photons the root-mean-square (RMS) WFE can be reduced to $\simλ/1000$, which is 1 nm RMS in the context of the SCExAO system. We find that the maximum WFE that can be corrected in one iteration is $\simλ/8$ RMS or $\sim$200 nm RMS (SCExAO). Furthermore, we demonstrate the SCExAO vAPP capabilities by measuring and controlling the lowest 30 Zernike modes with the internal source and on-sky. On-sky, we report a raw contrast improvement of a factor $\sim$2 between 2 and 4 $λ/D$ after 5 iterations of closed-loop correction. When artificially introducing 150 nm RMS WFE, the algorithm corrects it within 5 iterations of closed-loop operation. FPWFS with the vAPP's coronagraphic PSFs is a powerful technique since it integrates coronagraphy and wavefront sensing, eliminating the need for additional probes and thus resulting in a $100\%$ science duty cycle and maximum throughput for the target. △ Less

Submitted 18 September, 2019; originally announced September 2019.

Comments: Accepted for publication in Astronomy&Astrophysics. 19 pages, 15 figures

Journal ref: A&A 632, A48 (2019)

State Identification for Labeled Transition Systems with Inputs and Outputs

Authors: Petra van den Bos, Frits Vaandrager

Abstract: For Finite State Machines (FSMs) a rich testing theory has been developed to discover aspects of their behavior and ensure their correct functioning. Although this theory is widely used, e.g., to check conformance of protocol implementations, its applicability is limited by restrictions of the FSM framework: the fact that inputs and outputs alternate in an FSM, and outputs are fully determined by… ▽ More For Finite State Machines (FSMs) a rich testing theory has been developed to discover aspects of their behavior and ensure their correct functioning. Although this theory is widely used, e.g., to check conformance of protocol implementations, its applicability is limited by restrictions of the FSM framework: the fact that inputs and outputs alternate in an FSM, and outputs are fully determined by the previous input and state. Labeled Transition Systems with inputs and outputs (LTSs), as studied in ioco testing theory, provide a richer framework for testing component oriented systems, but lack the algorithms for test generation from FSM theory. In this article, we propose an algorithm for the fundamental problem of state identification during testing of LTSs. Our algorithm is a direct generalization of the well-known algorithm for computing adaptive distinguishing sequences for FSMs proposed by Lee & Yannakakis. Our algorithm has to deal with so-called compatible states, states that cannot be distinguished in case of an adversarial system-under-test. Analogous to the result of Lee & Yannakakis, we prove that if an (adaptive) test exists that distinguishes all pairs of incompatible states of an LTS, our algorithm will find one. In practice, such adaptive tests typically do not exist. However, in experiments with an implementation of our algorithm on an industrial benchmark, we find that tests produced by our algorithm still distinguish more than 99% of the incompatible state pairs. △ Less

Submitted 22 October, 2019; v1 submitted 25 July, 2019; originally announced July 2019.

KM3NeT front-end and readout electronics system: hardware, firmware and software

Authors: The KM3NeT Collaboration, S. Aiello, F. Ameli, M. Andre, G. Androulakis, M. Anghinolfi, G. Anton, M. Ardid, J. Aublin, C. Bagatelas, G. Barbarino, B. Baret, S. Basegmez du Pree, A. Belias, E. Berbee, A. M. van den Berg, V. Bertin, V. van Beveren, S. Biagi, A. Biagioni, S. Bianucci, M. Billault, M. Bissinger, P. Bos, J. Boumaaza , et al. (215 additional authors not shown)

Abstract: The KM3NeT research infrastructure being built at the bottom of the Mediterranean Sea will host water-Cherenkov telescopes for the detection of cosmic neutrinos. The neutrino telescopes will consist of large volume three-dimensional grids of optical modules to detect the Cherenkov light from charged particles produced by neutrino-induced interactions. Each optical module houses 31 3-inch photomult… ▽ More The KM3NeT research infrastructure being built at the bottom of the Mediterranean Sea will host water-Cherenkov telescopes for the detection of cosmic neutrinos. The neutrino telescopes will consist of large volume three-dimensional grids of optical modules to detect the Cherenkov light from charged particles produced by neutrino-induced interactions. Each optical module houses 31 3-inch photomultiplier tubes, instrumentation for calibration of the photomultiplier signal and positioning of the optical module and all associated electronics boards. By design, the total electrical power consumption of an optical module has been capped at seven watts. This paper presents an overview of the front-end and readout electronics system inside the optical module, which has been designed for a 1~ns synchronization between the clocks of all optical modules in the grid during a life time of at least 20 years. △ Less

Submitted 29 July, 2019; v1 submitted 15 July, 2019; originally announced July 2019.

Comments: Prepared submission to Journal of Astronomical Telescopes, Instruments, and Systems (JATIS)

Hausdorff dimension of a set in the theory of continued fractions

Authors: Ayreena Bakhtawar, Philip Bos, Mumtaz Hussain

Abstract: In this article we calculate the Hausdorff dimension of the set \begin{equation*} \mathcal{F}(Φ)=\left\{ x\in \lbrack 0,1):\begin{aligned}a_{n+1}(x)a_n(x) \geq Φ(n) \ {\rm for \ infinitely \ many \ } n\in \mathbb N \ {\rm and } \\ a_{n+1}(x)< Φ(n) \ {\rm for \ all \ sufficiently \ large \ } n\in \mathbb N \end{aligned}\right\} \end{equation*} where $Φ:\mathbb{N}\rightarrow (1,\infty)$ is any fun… ▽ More In this article we calculate the Hausdorff dimension of the set \begin{equation*} \mathcal{F}(Φ)=\left\{ x\in \lbrack 0,1):\begin{aligned}a_{n+1}(x)a_n(x) \geq Φ(n) \ {\rm for \ infinitely \ many \ } n\in \mathbb N \ {\rm and } \\ a_{n+1}(x)< Φ(n) \ {\rm for \ all \ sufficiently \ large \ } n\in \mathbb N \end{aligned}\right\} \end{equation*} where $Φ:\mathbb{N}\rightarrow (1,\infty)$ is any function with $\lim_{n\to \infty} Φ(n)=\infty.$ This in turn contributes to the metrical theory of continued fractions as well as gives insights about the set of Dirichlet non-improvable numbers. △ Less

Submitted 22 May, 2019; originally announced May 2019.

Comments: 21 pages, preliminary version, any comments for improvements are appreciated

By-passing fluctuation theorems

Authors: Paul Boes, Rodrigo Gallego, Nelly H. Y. Ng, Jens Eisert, Henrik Wilming

Abstract: Fluctuation theorems impose constraints on possible work extraction probabilities in thermodynamical processes. These constraints are stronger than the usual second law, which is concerned only with average values. Here, we show that such constraints, expressed in the form of the Jarzysnki equality, can be bypassed if one allows for the use of catalysts - additional degrees of freedom that may bec… ▽ More Fluctuation theorems impose constraints on possible work extraction probabilities in thermodynamical processes. These constraints are stronger than the usual second law, which is concerned only with average values. Here, we show that such constraints, expressed in the form of the Jarzysnki equality, can be bypassed if one allows for the use of catalysts - additional degrees of freedom that may become correlated with the system from which work is extracted, but whose reduced state remains unchanged so that they can be re-used. This violation can be achieved both for small systems but also for macroscopic many-body systems and leads to positive work extraction per particle with finite probability from macroscopic states in equilibrium. In addition to studying such violations for a single system, we also discuss the scenario in which many parties use the same catalyst to induce local transitions. We show that there exist catalytic processes that lead to highly correlated work distributions, expected to have implications for stochastic and quantum thermodynamics. △ Less

Submitted 14 February, 2020; v1 submitted 2 April, 2019; originally announced April 2019.

Comments: 16 pages (6+10), published version

Journal ref: Quantum 4, 231 (2020)

Rigorous vector wave propagation for arbitrary flat media

Authors: Steven P. Bos, Sebastiaan Y. Haffert, Christoph U. Keller

Abstract: Precise modelling of the (off-axis) point spread function (PSF) to identify geometrical and polarization aberrations is important for many optical systems. In order to characterise the PSF of the system in all Stokes parameters, an end-to-end simulation of the system has to be performed in which Maxwells equations are rigorously solved. We present the first results of a python code that we are dev… ▽ More Precise modelling of the (off-axis) point spread function (PSF) to identify geometrical and polarization aberrations is important for many optical systems. In order to characterise the PSF of the system in all Stokes parameters, an end-to-end simulation of the system has to be performed in which Maxwells equations are rigorously solved. We present the first results of a python code that we are developing to perform multiscale end-to-end wave propagation simulations that include all relevant physics. Currently we can handle plane-parallel near- and far-field vector diffraction effects of propagating waves in homogeneous isotropic and anisotropic materials, refraction and reflection of flat parallel surfaces, interference effects in thin films and unpolarized light. We show that the code has a numerical precision on the order of 1E-16 for non-absorbing isotropic and anisotropic materials. For absorbing materials the precision is on the order of 1E-8. The capabilities of the code are demonstrated by simulating a converging beam reflecting from a flat aluminium mirror at normal incidence. △ Less

Submitted 24 November, 2018; originally announced November 2018.

Comments: 19 pages, 10 figures, presented at SPIE Optical Engineering + Applications, 2017, San Diego, California, United States

Journal ref: Proceedings Volume 10407, Polarization Science and Remote Sensing VIII; 1040709 (2017)

Fully broadband vAPP coronagraphs enabling polarimetric high contrast imaging

Authors: Steven P. Bos, David S. Doelman, Jos de Boer, Emiel H. Por, Barnaby Norris, Michael J. Escuti, Frans Snik

Abstract: We present designs for fully achromatic vector Apodizing Phase Plate (vAPP) coronagraphs, that implement low polarization leakage solutions and achromatic beam-splitting, enabling observations in broadband filters. The vAPP is a pupil plane optic, inducing the phase through the inherently achromatic geometric phase. We discuss various implementations of the broadband vAPP and set requirements on a… ▽ More We present designs for fully achromatic vector Apodizing Phase Plate (vAPP) coronagraphs, that implement low polarization leakage solutions and achromatic beam-splitting, enabling observations in broadband filters. The vAPP is a pupil plane optic, inducing the phase through the inherently achromatic geometric phase. We discuss various implementations of the broadband vAPP and set requirements on all the components of the broadband vAPP coronagraph to ensure that the leakage terms do not limit a raw contrast of 1E-5. Furthermore, we discuss superachromatic QWPs based of liquid crystals or quartz/MgF2 combinations, and several polarizer choices. As the implementation of the (broadband) vAPP coronagraph is fully based on polarization techniques, it can easily be extended to furnish polarimetry by adding another QWP before the coronagraph optic, which further enhances the contrast between the star and a polarized companion in reflected light. We outline several polarimetric vAPP system designs that could be easily implemented in existing instruments, e.g. SPHERE and SCExAO. △ Less

Submitted 24 November, 2018; originally announced November 2018.

Comments: 11 pages, 5 figures, presented at SPIE Astronomical Telescopes and Instrumentation 2018

Journal ref: Proceedings Volume 10706, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation III; 107065M (2018)

Bayesian cosmic density field inference from redshift space dark matter maps

Authors: E. G. Patrick Bos, Francisco-Shu Kitaura, Rien van de Weygaert

Abstract: We present a self-consistent Bayesian formalism to sample the primordial density fields compatible with a set of dark matter density tracers after cosmic evolution observed in redshift space. Previous works on density reconstruction did not self-consistently consider redshift space distortions or included an additional iterative distortion correction step. We present here the analytic solution of… ▽ More We present a self-consistent Bayesian formalism to sample the primordial density fields compatible with a set of dark matter density tracers after cosmic evolution observed in redshift space. Previous works on density reconstruction did not self-consistently consider redshift space distortions or included an additional iterative distortion correction step. We present here the analytic solution of coherent flows within a Hamiltonian Monte Carlo posterior sampling of the primordial density field. We test our method within the Zel'dovich approximation, presenting also an analytic solution including tidal fields and spherical collapse on small scales using augmented Lagrangian perturbation theory. Our resulting reconstructed fields are isotropic and their power spectra are unbiased compared to the true one defined by our mock observations. Novel algorithmic implementations are introduced regarding the mass assignment kernels when defining the dark matter density field and optimization of the time step in the Hamiltonian equations of motions. Our algorithm, dubbed barcode, promises to be specially suited for analysis of the dark matter cosmic web down to scales of a few Megaparsecs. This large scale structure is implied by the observed spatial distribution of galaxy clusters --- such as obtained from X-ray, SZ or weak lensing surveys --- as well as that of the intergalactic medium sampled by the Lyman alpha forest or perhaps even by deep hydrogen intensity mapping. In these cases, virialized motions are negligible, and the tracers cannot be modeled as point-like objects. It could be used in all of these contexts as a baryon acoustic oscillation reconstruction algorithm. △ Less

Submitted 8 June, 2019; v1 submitted 11 October, 2018; originally announced October 2018.

Comments: 34 pages, 25 figures, 1 table. Submitted to MNRAS. Accompanying code at https://github.com/egpbos/barcode

Tester versus Bug: A Generic Framework for Model-Based Testing via Games

Authors: Petra van den Bos, Marielle Stoelinga

Abstract: We propose a generic game-based approach for test case generation. We set up a game between the tester and the System Under Test, in such a way that test cases correspond to game strategies, and the conformance relation ioco corresponds to alternating refinement. We show that different test assumptions from the literature can be easily incorporated, by slightly varying the moves in the games an… ▽ More We propose a generic game-based approach for test case generation. We set up a game between the tester and the System Under Test, in such a way that test cases correspond to game strategies, and the conformance relation ioco corresponds to alternating refinement. We show that different test assumptions from the literature can be easily incorporated, by slightly varying the moves in the games and their outcomes. In this way, our framework allows a wide plethora of game-theoretic techniques to be deployed for model based testing. △ Less

Submitted 9 September, 2018; originally announced September 2018.

Comments: In Proceedings GandALF 2018, arXiv:1809.02416

Journal ref: EPTCS 277, 2018, pp. 118-132

Von Neumann entropy from unitarity

Authors: P. Boes, J. Eisert, R. Gallego, M. P. Mueller, H. Wilming

Abstract: The von Neumann entropy is a key quantity in quantum information theory and, roughly speaking, quantifies the amount of quantum information contained in a state when many identical and independent i.i.d. copies of the state are available, in a regime that is often referred to as being asymptotic. In this work, we provide a new operational characterization of the von Neumann entropy which neither r… ▽ More The von Neumann entropy is a key quantity in quantum information theory and, roughly speaking, quantifies the amount of quantum information contained in a state when many identical and independent i.i.d. copies of the state are available, in a regime that is often referred to as being asymptotic. In this work, we provide a new operational characterization of the von Neumann entropy which neither requires an i.i.d. limit nor any explicit randomness. We do so by showing that the von Neumann entropy fully characterizes single-shot state transitions in unitary quantum mechanics, as long as one has access to a catalyst - an ancillary system that can be re-used after the transition - and an environment which has the effect of dephasing in a preferred basis. Building upon these insights, we formulate and provide evidence for the catalytic entropy conjecture, which states that the above result holds true even in the absence of decoherence. If true, this would prove an intimate connection between single-shot state transitions in unitary quantum mechanics and the von Neumann entropy. Our results add significant support to recent insights that, contrary to common wisdom, the standard von Neumann entropy also characterizes single-shot situations and opens up the possibility for operational single-shot interpretations of other standard entropic quantities. We discuss implications of these insights to readings of the third law of quantum thermodynamics and hint at potentially profound implications to holography. △ Less

Submitted 23 July, 2018; originally announced July 2018.

Comments: 4+5 pages, 1 figure

Journal ref: Phys. Rev. Lett. 122, 210402 (2019)

The sets of Dirichlet non-improvable numbers vs well-approximable numbers

Authors: Ayreena Bakhtawar, Philip Bos, Mumtaz Hussain

Abstract: Let $Ψ:[1,\infty )\rightarrow \mathbb{R}_{+}$ be a non-decreasing function, $a_{n}(x)$ the $n$'{th} partial quotient of $x$ and $q_{n}(x)$ the denominator of the $n$'{th} convergent. The set of $Ψ$-Dirichlet non-improvable numbers \begin{equation*} G(Ψ):=\Big\{x\in \lbrack 0,1):a_{n}(x)a_{n+1}(x)\,>\,Ψ\big(q_{n}(x) \big)\ \mathrm{for\ infinitely\ many}\ n\in \mathbb{N}\Big\}, \end{equation*} is re… ▽ More Let $Ψ:[1,\infty )\rightarrow \mathbb{R}_{+}$ be a non-decreasing function, $a_{n}(x)$ the $n$'{th} partial quotient of $x$ and $q_{n}(x)$ the denominator of the $n$'{th} convergent. The set of $Ψ$-Dirichlet non-improvable numbers \begin{equation*} G(Ψ):=\Big\{x\in \lbrack 0,1):a_{n}(x)a_{n+1}(x)\,>\,Ψ\big(q_{n}(x) \big)\ \mathrm{for\ infinitely\ many}\ n\in \mathbb{N}\Big\}, \end{equation*} is related with the classical set of $1/q^{2}Ψ(q)$-approximable numbers $ \mathcal{K}(Ψ)$ in the sense that $\mathcal{K}(3Ψ)\subset G(Ψ)$. Both of these sets enjoy the same $s$-dimensional Hausdorff measure criterion for $s\in (0,1)$. We prove that the set $G(Ψ)\setminus \mathcal{K}(3Ψ)$ is uncountable by proving that its Hausdorff dimension is the same as that for the sets $\mathcal{K}(Ψ)$ and $G(Ψ)$. This gives an affirmative answer to a question raised by Hussain-Kleinbock-Wadleigh-Wang (2018). △ Less

Submitted 16 May, 2019; v1 submitted 2 June, 2018; originally announced June 2018.

Comments: 17 pages, comments welcome, to appear in Ergodic Theory and Dynamical System

Catalytic quantum randomness

Authors: P. Boes, H. Wilming, R. Gallego, J. Eisert

Abstract: Randomness is a defining element of mixing processes in nature and an essential ingredient to many protocols in quantum information. In this work, we investigate how much randomness is required to transform a given quantum state into another one. Specifically, we ask whether there is a gap between the power of a classical source of randomness compared to that of a quantum one. We provide a complet… ▽ More Randomness is a defining element of mixing processes in nature and an essential ingredient to many protocols in quantum information. In this work, we investigate how much randomness is required to transform a given quantum state into another one. Specifically, we ask whether there is a gap between the power of a classical source of randomness compared to that of a quantum one. We provide a complete answer to these questions, by identifying provably optimal protocols for both classical and quantum sources of randomness, based on a dephasing construction. We find that in order to implement any noisy transition on a $d$-dimensional quantum system it is necessary and sufficient to have a quantum source of randomness of dimension $\sqrt{d}$ or a classical one of dimension $d$. Interestingly, coherences provided by quantum states in a source of randomness offer a quadratic advantage. The process we construct has the additional features to be robust and catalytic, i.e., the source of randomness can be re-used. Building upon this formal framework, we illustrate that this dephasing construction can serve as a useful primitive in both equilibration and quantum information theory: We discuss applications describing the smallest measurement device, capturing the smallest equilibrating environment allowed by quantum mechanics, or forming the basis for a cryptographic private quantum channel. We complement the exact analysis with a discussion of approximate protocols based on quantum expanders deriving from discrete Weyl systems. This gives rise to equilibrating environments of remarkably small dimension. Our results highlight the curious feature of randomness that residual correlations and dimension can be traded against each other. △ Less

Submitted 6 February, 2019; v1 submitted 9 April, 2018; originally announced April 2018.

Comments: 18 pages, 6 figures; Fixed typo in expander theorem;

Journal ref: Phys. Rev. X 8, 041016 (2018)