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Free Multiplicative Convolution and Erlang Moments in Monitored Quantum Transport
Authors:
Joon Hyung Lee
Abstract:
We study the transmission eigenvalues of monitored Haar products \[
B_L=(PS_L)(PS_{L-1})\cdots(PS_1), \] where the $S_i$ are independent Haar unitaries and $P$ is a deterministic projection. For fixed $L$, we prove that the empirical eigenvalue distribution of $B_L^\dagger B_L$ converges to $ν_c^{\boxtimes L}$, where $ν_c=(1-c)δ_1+cδ_0$. We then take the free small-loss limit and identify the li…
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We study the transmission eigenvalues of monitored Haar products \[
B_L=(PS_L)(PS_{L-1})\cdots(PS_1), \] where the $S_i$ are independent Haar unitaries and $P$ is a deterministic projection. For fixed $L$, we prove that the empirical eigenvalue distribution of $B_L^\dagger B_L$ converges to $ν_c^{\boxtimes L}$, where $ν_c=(1-c)δ_1+cδ_0$. We then take the free small-loss limit and identify the limiting law by \[
S_{μ_τ}(z)=\exp\left(\fracτ{1+z}\right). \] Lagrange inversion gives explicit Erlang-type moments, explaining the polynomials appearing in Beenakker's recursion. We also record spectral consequences, including the atom $μ_τ(\{1\})=(1-τ)_+$ and the real branch point $τ\mathrm{e}^{1-τ}$, and formulate the diagonal scaling $L\simτN$, $c=1/N$, as a quantitative convergence problem supported by low-order moment checks.
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Submitted 6 July, 2026;
originally announced July 2026.
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Quadratic Sums-of-Powers for Fixed-Parameter Tractable Quantum-Circuit Simulation
Authors:
Alexis de Colnet,
Floris Geerts,
Rihan Hai,
Alfons Laarman,
Joon Hyung Lee,
Guillermo A. Pérez
Abstract:
Strongly simulating a quantum circuit, that is, computing an output amplitude, can be done by summing the circuit's Feynman paths: a weighted count over assignments to Boolean path variables. The circuit's gates induce correlations among these variables, forming a graph whose structure controls several exact simulation routes. This sum-of-powers (SOP) viewpoint underlies recent simulators built on…
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Strongly simulating a quantum circuit, that is, computing an output amplitude, can be done by summing the circuit's Feynman paths: a weighted count over assignments to Boolean path variables. The circuit's gates induce correlations among these variables, forming a graph whose structure controls several exact simulation routes. This sum-of-powers (SOP) viewpoint underlies recent simulators built on binary decision diagrams and weighted model counting.
For a quadratic SOP with $n$ variables, even modulus $r$, and a rank-decomposition of its variable graph of width $k$, our dynamic program (DP) computes an amplitude using only $O(4^kpoly(n))$ arithmetic operations. For Clifford$+T$ circuits, the amplitude is given by an SOP with modulus $8$.
Rank-width never exceeds linear rank-width, which governs some decision-diagram approaches, and is at most one greater than the Markov--Shi contraction complexity of the circuit tensor network. Moreover, there are non-Clifford families of bounded rank-width where both competing parameters diverge. We also present a stabilizer-rank optimization, exploiting that the DP tables are stabilizer-type Gauss sums. Each subtree runs at the width price of its cut-ranks or at a magic price that discharges the non-Clifford phases below it. The resulting best total cost never exceeds $O(4^kpoly(n))$, yet is polynomial on mixed families where the pure rank-width and pure $T$-count guarantees are both exponential. Clifford amplitudes take polynomial time on any graph, the exact-amplitude consequence of Gottesman--Knill.
A prototype evaluation on standard circuit benchmarks finds treewidth bucket elimination the strongest baseline, with the new rank-width DP complementary: it wins on structured families where treewidth blows up.
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Submitted 19 August, 2026; v1 submitted 28 May, 2026;
originally announced May 2026.
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Search-Driven Clause Learning for Product-State Quantum $k$-SAT (PRODSAT-QSAT)
Authors:
Samuel González-Castillo,
Joon Hyung Lee,
Alfons Laarman
Abstract:
We study PRODSAT-QSAT($k$): given rank-one $k$-local projectors, determine whether a quantum $k$-SAT instance admits a satisfying product state. We present a CDCL-style refutation framework that searches a finite partition of each qubit's Bloch sphere while a sound theory solver checks region feasibility using a geometric overapproximation of the projection amplitudes for each constraint. When the…
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We study PRODSAT-QSAT($k$): given rank-one $k$-local projectors, determine whether a quantum $k$-SAT instance admits a satisfying product state. We present a CDCL-style refutation framework that searches a finite partition of each qubit's Bloch sphere while a sound theory solver checks region feasibility using a geometric overapproximation of the projection amplitudes for each constraint. When the theory solver proves that no state in a region can satisfy a constraint, it produces a sound conflict clause that blocks that region; accumulated blocking clauses can yield a global result of product-state unsatisfiability (UN-PRODSAT). We formalise the problem, prove the soundness of the clause-learning rule, and describe a practical algorithm and implementation.
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Submitted 20 March, 2026;
originally announced March 2026.
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Ultrastrong Coupling and Coherent Dynamics in a Gate-Tunable Transmon Qubit
Authors:
I. Casal Iglesias,
F. J. Matute-Cañadas,
G. O. Steffensen,
A. Ibabe,
L. Splitthoff,
T. Kanne,
J. Nygard,
V. Rollano,
D. Granados,
A. Gomez,
R. Aguado,
A. Levy Yeyati,
E. J. H. Lee
Abstract:
Ultrastrong light-matter coupling (USC) gives access to exotic quantum phenomena and promises faster quantum gates, yet coherent time-domain control in this regime remains largely unexplored. Here, we realize USC in a hybrid system consisting of an InAs nanowire-based gatemon qubit coupled to a superconducting resonator. Spectroscopy reveals an avoided crossing that cannot be captured by the Jayne…
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Ultrastrong light-matter coupling (USC) gives access to exotic quantum phenomena and promises faster quantum gates, yet coherent time-domain control in this regime remains largely unexplored. Here, we realize USC in a hybrid system consisting of an InAs nanowire-based gatemon qubit coupled to a superconducting resonator. Spectroscopy reveals an avoided crossing that cannot be captured by the Jaynes-Cummings (JC) model, as well as photon-number-dependent transitions whose energies deviate markedly from the JC ladder expected in the strong coupling regime. Beyond demonstrating USC, we achieve time-resolved coherent control of the qubit and measure coherence times comparable to gatemons operating outside the USC regime. These results establish that hybrid semiconductor-superconductor qubits can retain coherent control in USC and provide a platform for exploring quantum dynamics and device concepts in this regime.
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Submitted 19 March, 2026;
originally announced March 2026.
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Quantum Physics using Weighted Model Counting
Authors:
Dirck van den Ende,
Joon Hyung Lee,
Alfons Laarman,
Henning Basold
Abstract:
Weighted model counting (WMC) has proven effective at a range of tasks within computer science, physics, and beyond. However, existing approaches for using WMC in quantum physics only target specific problem instances, lacking a general framework for expressing problems using WMC. This limits the reusability of these approaches in other applications and risks a lack of mathematical rigor on a per-…
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Weighted model counting (WMC) has proven effective at a range of tasks within computer science, physics, and beyond. However, existing approaches for using WMC in quantum physics only target specific problem instances, lacking a general framework for expressing problems using WMC. This limits the reusability of these approaches in other applications and risks a lack of mathematical rigor on a per-instance basis. We present an approach for expressing linear algebraic problems, specifically those present in physics and quantum computing, as WMC instances. We do this by introducing a framework that converts Dirac notation to WMC problems. We build up this framework theoretically, using a type system and denotational semantics, and provide an implementation in Python. We demonstrate the effectiveness of our framework in calculating the partition functions of several physical models: The transverse-field Ising model (quantum) and the Potts model (classical). The results suggest that heuristics developed in automated reasoning can be systematically applied to a wide class of problems in quantum physics through our framework.
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Submitted 28 April, 2026; v1 submitted 28 August, 2025;
originally announced August 2025.
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Thermoelectric processes of quantum normal-superconductor interfaces
Authors:
L. Arrachea,
A. Braggio,
P. Burset,
E. J. H. Lee,
A. Levy Yeyati,
R. Sánchez
Abstract:
Superconducting interfaces have recently been demonstrated to contain a rich variety of effects that give rise to sizable thermoelectric responses and unexpected thermal properties, despite traditionally being considered poor thermoelectrics due to their intrinsic electron-hole symmetry. We review different mechanisms driving this response in hybrid normal-superconducting junctions, depending on t…
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Superconducting interfaces have recently been demonstrated to contain a rich variety of effects that give rise to sizable thermoelectric responses and unexpected thermal properties, despite traditionally being considered poor thermoelectrics due to their intrinsic electron-hole symmetry. We review different mechanisms driving this response in hybrid normal-superconducting junctions, depending on the dimensionality of the mesoscopic interface. In addition to discussing heat to power conversion, cooling and heat transport, special emphasis is put on physical properties of hybrid devices that can be revealed by the thermoelectric effect.
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Submitted 10 September, 2025; v1 submitted 12 May, 2025;
originally announced May 2025.
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Long-lived quantum correlation by cavity-mediated subradiance
Authors:
Kyu-Young Kim,
Jin Hee Lee,
Woong Bae Jeon,
Dong Hyun Park,
Suk In Park,
Jin Dong Song,
Changhyoup Lee,
Je-Hyung Kim
Abstract:
Cooperative effects such as super(sub)radiance in quantum systems arise from the interplay among quantum emitters. While bright superradiant states have been extensively studied and yielded significant insights into cooperative phenomena, subradiant states have remained less explored due to their inherently dark state nature. However, subradiance holds significant potential as valuable quantum res…
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Cooperative effects such as super(sub)radiance in quantum systems arise from the interplay among quantum emitters. While bright superradiant states have been extensively studied and yielded significant insights into cooperative phenomena, subradiant states have remained less explored due to their inherently dark state nature. However, subradiance holds significant potential as valuable quantum resources that exploit long-lived and large-scale entanglement, which is a key for advancing quantum information technologies. Here, we demonstrate a long-lived subradiant state among multiple quantum emitters coupled to a directional low Q cavity. In a tailored photonic environment with balanced cavity dissipation, emitter-field coupling strength, and incoherent pumping, two coupled quantum dots exhibit a steady-state population in a subradiant state with highly negative cooperativity. As an important hallmark of a subradiant state, the system shows large photon bunching (g^((2))(0)>>2) and suppressed single-photon decay. In addition, controlling the excitation wavelength provides a useful tool for manipulating dephasing and the number of coupled emitters, which leads to significant changes in photon statistics. Our approach to inducing cavity-mediated subradiance paves the way for creating and harnessing quantum correlations in quantum emitters via a long-lived entangled quantum state, essential for quantum storage and metrology.
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Submitted 12 December, 2024;
originally announced December 2024.
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Tomography of Ultra-relativistic Nuclei with Polarized Photon-gluon Collisions
Authors:
STAR Collaboration,
M. S. Abdallah,
B. E. Aboona,
J. Adam,
L. Adamczyk,
J. R. Adams,
J. K. Adkins,
G. Agakishiev,
I. Aggarwal,
M. M. Aggarwal,
Z. Ahammed,
A. Aitbaev,
I. Alekseev,
D. M. Anderson,
A. Aparin,
E. C. Aschenauer,
M. U. Ashraf,
F. G. Atetalla,
G. S. Averichev,
V. Bairathi,
W. Baker,
J. G. Ball Cap,
K. Barish,
A. Behera,
R. Bellwied
, et al. (370 additional authors not shown)
Abstract:
A linearly polarized photon can be quantized from the Lorentz-boosted electromagnetic field of a nucleus traveling at ultra-relativistic speed. When two relativistic heavy nuclei pass one another at a distance of a few nuclear radii, the photon from one nucleus may interact through a virtual quark-antiquark pair with gluons from the other nucleus forming a short-lived vector meson (e.g. ${ρ^0}$).…
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A linearly polarized photon can be quantized from the Lorentz-boosted electromagnetic field of a nucleus traveling at ultra-relativistic speed. When two relativistic heavy nuclei pass one another at a distance of a few nuclear radii, the photon from one nucleus may interact through a virtual quark-antiquark pair with gluons from the other nucleus forming a short-lived vector meson (e.g. ${ρ^0}$). In this experiment, the polarization was utilized in diffractive photoproduction to observe a unique spin interference pattern in the angular distribution of ${ρ^0\rightarrowπ^+π^-}$ decays. The observed interference is a result of an overlap of two wave functions at a distance an order of magnitude larger than the ${ρ^0}$ travel distance within its lifetime. The strong-interaction nuclear radii were extracted from these diffractive interactions, and found to be $6.53\pm 0.06$ fm ($^{197} {\rm Au }$) and $7.29\pm 0.08$ fm ($^{238} {\rm U}$), larger than the nuclear charge radii. The observable is demonstrated to be sensitive to the nuclear geometry and quantum interference of non-identical particles.
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Submitted 4 April, 2022;
originally announced April 2022.
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High resolution, High contrast optical interface for defect qubits
Authors:
Jong Sung Moon,
Haneul Lee,
Jin Hee Lee,
Woong Bae Jeon,
Dowon Lee,
Junghyun Lee,
Seoyoung Paik,
Sang-Wook Han,
Rolf Reuter,
Andrej Denisenko,
Joerg Wrachtrup,
Sang-Yun Lee,
Je-Hyung Kim
Abstract:
Point defects in crystals provide important building blocks for quantum applications. To initialize, control, and read-out their quantum states, an efficient optical interface for addressing defects with photons is required. However, conventional confocal fluorescence microscopy with high refractive index crystals has limited photon collection efficiency and spatial resolution. Here, we demonstrat…
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Point defects in crystals provide important building blocks for quantum applications. To initialize, control, and read-out their quantum states, an efficient optical interface for addressing defects with photons is required. However, conventional confocal fluorescence microscopy with high refractive index crystals has limited photon collection efficiency and spatial resolution. Here, we demonstrate high resolution, high contrast imaging for defects qubits using microsphere-assisted confocal microscopy. A microsphere provides an excellent optical interface for point defects with a magnified virtual image that improves spatial resolution up to ~$λ$/5 as well as an optical signal-to-noise ratio by four times. These features enable individual optical addressing of single photons and single spins of spatially-unresolved defects in conventional confocal microscopy with improved signal contrast. The combined optical tweezers show the possibility of positioning or scanning the microspheres for deterministic coupling and wide-field imaging of defects. The approach does not require any complicated fabrication and additional optical system but uses simple micro-optics off-the-shelf. From these distinctive advantages of the microspheres, our approach can provide an efficient way for imaging and addressing closely-spaced defects with higher resolution and sensitivity.
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Submitted 13 February, 2021;
originally announced February 2021.
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arXiv:2102.02644
[pdf]
cond-mat.mes-hall
cond-mat.mtrl-sci
cond-mat.str-el
cond-mat.supr-con
quant-ph
The 2021 Quantum Materials Roadmap
Authors:
Feliciano Giustino,
Jin Hong Lee,
Felix Trier,
Manuel Bibes,
Stephen M Winter,
Roser Valentí,
Young-Woo Son,
Louis Taillefer,
Christoph Heil,
Adriana I. Figueroa,
Bernard Plaçais,
QuanSheng Wu,
Oleg V. Yazyev,
Erik P. A. M. Bakkers,
Jesper Nygård,
Pol Forn-Diaz,
Silvano De Franceschi,
J. W. McIver,
L. E. F. Foa Torres,
Tony Low,
Anshuman Kumar,
Regina Galceran,
Sergio O. Valenzuela,
Marius V. Costache,
Aurélien Manchon
, et al. (4 additional authors not shown)
Abstract:
In recent years, the notion of Quantum Materials has emerged as a powerful unifying concept across diverse fields of science and engineering, from condensed-matter and cold atom physics to materials science and quantum computing. Beyond traditional quantum materials such as unconventional superconductors, heavy fermions, and multiferroics, the field has significantly expanded to encompass topologi…
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In recent years, the notion of Quantum Materials has emerged as a powerful unifying concept across diverse fields of science and engineering, from condensed-matter and cold atom physics to materials science and quantum computing. Beyond traditional quantum materials such as unconventional superconductors, heavy fermions, and multiferroics, the field has significantly expanded to encompass topological quantum matter, two-dimensional materials and their van der Waals heterostructures, Moire materials, Floquet time crystals, as well as materials and devices for quantum computation with Majorana fermions. In this Roadmap collection we aim to capture a snapshot of the most recent developments in the field, and to identify outstanding challenges and emerging opportunities. The format of the Roadmap, whereby experts in each discipline share their viewpoint and articulate their vision for quantum materials, reflects the dynamic and multifaceted nature of this research area, and is meant to encourage exchanges and discussions across traditional disciplinary boundaries. It is our hope that this collective vision will contribute to sparking new fascinating questions and activities at the intersection of materials science, condensed matter physics, device engineering, and quantum information, and to shaping a clearer landscape of quantum materials science as a new frontier of interdisciplinary scientific inquiry.
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Submitted 4 February, 2021;
originally announced February 2021.
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Quantum tensor singular value decomposition with applications to recommendation systems
Authors:
Xiaoqiang Wang,
Lejia Gu,
Joseph Heung-wing Joseph Lee,
Guofeng Zhang
Abstract:
In this paper, we present a quantum singular value decomposition algorithm for third-order tensors inspired by the classical algorithm of tensor singular value decomposition (t-svd) and then extend it to order-$p$ tensors. It can be proved that the quantum version of the t-svd for a third-order tensor $\mathcal{A} \in \mathbb{R}^{N\times N \times N}$ achieves the complexity of…
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In this paper, we present a quantum singular value decomposition algorithm for third-order tensors inspired by the classical algorithm of tensor singular value decomposition (t-svd) and then extend it to order-$p$ tensors. It can be proved that the quantum version of the t-svd for a third-order tensor $\mathcal{A} \in \mathbb{R}^{N\times N \times N}$ achieves the complexity of $\mathcal{O}(N{\rm polylog}(N))$, an exponential speedup compared with its classical counterpart. As an application, we propose a quantum algorithm for recommendation systems which incorporates the contextual situation of users to the personalized recommendation. We provide recommendations varying with contexts by measuring the output quantum state corresponding to an approximation of this user's preferences. This algorithm runs in expected time $\mathcal{O}(N{\rm polylog}(N){\rm poly}(k)),$ if every frontal slice of the preference tensor has a good rank-$k$ approximation. At last, we provide a quantum algorithm for tensor completion based on a different truncation method which is tested to have a good performance in dynamic video completion.
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Submitted 3 February, 2020; v1 submitted 2 October, 2019;
originally announced October 2019.
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Dissipation-driven nonclassical state generation in optomechanics with squeezed light
Authors:
Jae Hoon Lee,
Junho Suh,
Hyojun Seok
Abstract:
We study an optomechanical system for the purpose of generating a nonclassical mechanical state when a mechanical oscillator is quadratically coupled to a single-mode cavity field driven by a squeezed optical field. The system corresponds to a regime where the optical dissipation dominates both the mechanical damping and the optomechanical coupling. We identify that multi-phonon processes emerge i…
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We study an optomechanical system for the purpose of generating a nonclassical mechanical state when a mechanical oscillator is quadratically coupled to a single-mode cavity field driven by a squeezed optical field. The system corresponds to a regime where the optical dissipation dominates both the mechanical damping and the optomechanical coupling. We identify that multi-phonon processes emerge in the optomechanical system and show that a mechanical oscillator prepared in the ground state will evolve into an amplitude-squared squeezed vacuum state. The Wigner distribution of the steady state of the mechanical oscillator is non-Gaussian exhibiting quantum interference and four-fold symmetry. This nonclassical mechanical state, generated via reservoir engineering, can be used for quantum correlation measurements of the position and momentum of the mechanics below the standard quantum limit.
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Submitted 18 June, 2018;
originally announced June 2018.
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Quantum reservoir engineering through quadratic optomechanical interaction in the reversed dissipation regime
Authors:
Jae Hoon Lee,
H. Seok
Abstract:
We explore the electromagnetic field coupled to a mechanical resonator via quadratic optomechanical interaction in the reversed dissipation regime where the mechanical damping rate is much larger than the cavity field dissipation rate. It is shown that in this regime, the cavity field effectively acquires an additional reservoir which is conditioned by the temperature of the mechanical bath as wel…
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We explore the electromagnetic field coupled to a mechanical resonator via quadratic optomechanical interaction in the reversed dissipation regime where the mechanical damping rate is much larger than the cavity field dissipation rate. It is shown that in this regime, the cavity field effectively acquires an additional reservoir which is conditioned by the temperature of the mechanical bath as well as the mechanical damping rate. We analytically find the steady-state mean photon number and the critical temperature of the mechanical oscillator to cool or heat the coupled electromagnetic field. We also show that in the case of quadratic coupling, the temperature of the mechanical oscillator can be estimated in the quantum regime by observing the noise spectrum of the cavity field.
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Submitted 1 September, 2017;
originally announced September 2017.
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Atom-Light Interactions in Photonic Crystals
Authors:
A. Goban,
C. -L. Hung,
S. -P. Yu,
J. D. Hood,
J. A. Muniz,
J. H. Lee,
M. J. Martin,
A. C. McClung,
K. S. Choi,
D. E. Chang,
O. Painter,
H. J. Kimble
Abstract:
The integration of nanophotonics and atomic physics has been a long-sought goal that would open new frontiers for optical physics. Here, we report the development of the first integrated optical circuit with a photonic crystal capable of both localizing and interfacing atoms with guided photons in the device. By aligning the optical bands of a photonic crystal waveguide (PCW) with selected atomic…
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The integration of nanophotonics and atomic physics has been a long-sought goal that would open new frontiers for optical physics. Here, we report the development of the first integrated optical circuit with a photonic crystal capable of both localizing and interfacing atoms with guided photons in the device. By aligning the optical bands of a photonic crystal waveguide (PCW) with selected atomic transitions, our platform provides new opportunities for novel quantum transport and many-body phenomena by way of photon-mediated atomic interactions along the PCW. From reflection spectra measured with average atom number N = 1.1$\pm$0.4, we infer that atoms are localized within the PCW by Casimir-Polder and optical dipole forces. The fraction of single-atom radiative decay into the PCW is $Γ_{\rm 1D}/Γ'$ = 0.32$\pm$0.08, where $Γ_{1D}$ is the rate of emission into the guided mode and $Γ'$ is the decay rate into all other channels. $Γ_{\rm 1D}/Γ'$ is quoted without enhancement due to an external cavity and is unprecedented in all current atom-photon interfaces.
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Submitted 12 December, 2013;
originally announced December 2013.
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Robust site-resolved quantum gates in an optical lattice via inhomogeneous control
Authors:
Jae Hoon Lee,
Enrique Montano,
Ivan H. Deutsch,
Poul S. Jessen
Abstract:
Ultracold atoms in optical lattices are an important platform for quantum information science, lending itself naturally to quantum simulation of many-body physics and providing a possible path towards a scalable quantum computer. To realize its full potential, atoms at individual lattice sites must be accessible to quantum control and measurement. This challenge has so far been met with a combinat…
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Ultracold atoms in optical lattices are an important platform for quantum information science, lending itself naturally to quantum simulation of many-body physics and providing a possible path towards a scalable quantum computer. To realize its full potential, atoms at individual lattice sites must be accessible to quantum control and measurement. This challenge has so far been met with a combination of high-resolution microscopes and resonance addressing that have enabled both site-resolved imaging and spin-flips. Here we show that methods borrowed from the field of inhomogeneous control can greatly increase the performance of resonance addressing in optical lattices, allowing us to target arbitrary single-qubit gates on desired sites, with minimal crosstalk to neighboring sites and greatly improved robustness against uncertainty in the lattice position. We further demonstrate the simultaneous implementation of different gates at adjacent sites with a single global control waveform. Coherence is verified through two-pulse Ramsey interrogation, and randomized benchmarking is used to measure an average gate fidelity of ~95%. Our control-based approach to reduce crosstalk and increase robustness is broadly applicable in optical lattices irrespective of geometry, and may be useful also on other platforms for quantum information processing, such as ion traps and nitrogen-vacancy centers in diamond.
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Submitted 3 June, 2013;
originally announced June 2013.
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Microwave Control of Atomic Motion in Optical Lattices
Authors:
Leonid Förster,
Michał Karski,
Jai-Min Choi,
Andreas Steffen,
Wolfgang Alt,
Dieter Meschede,
Artur Widera,
Enrique Montano,
Jae Hoon Lee,
Worawarong Rakreungdet,
Poul S. Jessen
Abstract:
We control the quantum mechanical motion of neutral atoms in an optical lattice by driving microwave transitions between spin states whose trapping potentials are spatially offset. Control of this offset with nanometer precision allows for adjustment of the coupling strength between different motional states, analogous to an adjustable effective Lamb-Dicke factor. This is used both for efficient…
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We control the quantum mechanical motion of neutral atoms in an optical lattice by driving microwave transitions between spin states whose trapping potentials are spatially offset. Control of this offset with nanometer precision allows for adjustment of the coupling strength between different motional states, analogous to an adjustable effective Lamb-Dicke factor. This is used both for efficient one-dimensional sideband cooling of individual atoms to a vibrational ground state population of 97%, and to drive coherent Rabi oscillation between arbitrary pairs of vibrational states. We further show that microwaves can drive well resolved transitions between motional states in maximally offset, shallow lattices, and thus in principle allow for coherent control of long range quantum transport.
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Submitted 3 September, 2009;
originally announced September 2009.
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Accurate Microwave Control and Real-Time Diagnostics of Neutral Atom Qubits
Authors:
W. Rakreungdet,
J. H. Lee,
K. F. Lee,
B. E. Mischuck,
Enrique Montano,
P. S. Jessen
Abstract:
We demonstrate accurate single-qubit control in an ensemble of atomic qubits trapped in an optical lattice. The qubits are driven with microwave radiation, and their dynamics tracked by optical probe polarimetry. Real-time diagnostics is crucial to minimize systematic errors and optimize the performance of single-qubit gates, leading to fidelities of 0.99 for single-qubit pi rotations. We show t…
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We demonstrate accurate single-qubit control in an ensemble of atomic qubits trapped in an optical lattice. The qubits are driven with microwave radiation, and their dynamics tracked by optical probe polarimetry. Real-time diagnostics is crucial to minimize systematic errors and optimize the performance of single-qubit gates, leading to fidelities of 0.99 for single-qubit pi rotations. We show that increased robustness to large, deliberately introduced errors can be achieved through the use of composite rotations. However, during normal operation the combination of very small intrinsic errors and additional decoherence during the longer pulse sequences precludes any significant performance gain in our current experiment.
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Submitted 21 November, 2008;
originally announced November 2008.