-
A tale of two localizations: coexistence of flat bands and Anderson localization in a photonics-inspired amorphous system
Authors:
Elizabeth J. Dresselhaus,
Alexander Avdoshkin,
Zhetao Jia,
Matteo Secli,
Boubacar Kante,
Joel E. Moore
Abstract:
Emerging experimental platforms use amorphousness, a constrained form of disorder, to tailor meta-material properties. We study localization under this type of disorder in a family of 2D models generalizing recent experiments on photonic systems. Models in this family reside on amorphous analogs of kagomé lattices with fixed coordination number, vary by a tunable synthetic field, and remarkabaly,…
▽ More
Emerging experimental platforms use amorphousness, a constrained form of disorder, to tailor meta-material properties. We study localization under this type of disorder in a family of 2D models generalizing recent experiments on photonic systems. Models in this family reside on amorphous analogs of kagomé lattices with fixed coordination number, vary by a tunable synthetic field, and remarkabaly, permit exact results. We observe two kinds of localization that emerge in these models: Anderson localization by amorphous disorder, and the existence of compact, macroscopically degenerate localized states as in many crystalline flat bands. The flat-band-like degeneracy innate to kagomé lattices survives under amorphousness without on-site disorder. This phenomenon arises from the cooperation between the structure of the compact localized states and the geometry of the amorphous graph. More surprisingly, for particular values of the field, such states emerge in the amorphous system that were not present on the kagomé lattice in the same field. Outside the flat band, constrained amorphous graph geometry necessitates the existence of a fully delocalized state, near which we observe evidence of a localization-delocalization transition. Our platform serves as a demonstration of how the qualitative behavior of a disordered system can be tuned at fixed graph topology and lead to localization phenomena unique to amorphous systems that are not observed in their generically disordered counterparts.
△ Less
Submitted 15 August, 2025; v1 submitted 26 April, 2024;
originally announced April 2024.
-
Database of semiconductor point-defect properties for applications in quantum technologies
Authors:
Vsevolod Ivanov,
Alexander Ivanov,
Jacopo Simoni,
Prabin Parajuli,
Boubacar Kanté,
Thomas Schenkel,
Liang Tan
Abstract:
Solid-state point defects are attracting increasing attention in the field of quantum information science, because their localized states can act as a spin-photon interface in devices that store and transfer quantum information, which have been used for applications in quantum computing, sensing, and networking. In this work we have performed high-throughput calculations of over 50,000 point defec…
▽ More
Solid-state point defects are attracting increasing attention in the field of quantum information science, because their localized states can act as a spin-photon interface in devices that store and transfer quantum information, which have been used for applications in quantum computing, sensing, and networking. In this work we have performed high-throughput calculations of over 50,000 point defects in various semiconductors including diamond, silicon carbide, and silicon. Focusing on quantum applications, we characterize the relevant optical and electronic properties of these defects, including formation energies, spin characteristics, transition dipole moments, zero-phonon lines. We find 2331 composite defects which are stable in intrinsic silicon, which are then filtered to identify many new optically bright telecom spin qubit candidates and single-photon sources. All computed results and relaxed defect structures are made publicly available online at quantumdefects.com, a living database of defect characteristics which will be continually expanded with new defects and properties, and will enable researchers to select defects tailored to their applications.
△ Less
Submitted 28 March, 2023;
originally announced March 2023.
-
Quantum emitter formation dynamics and probing of radiation induced atomic disorder in silicon
Authors:
Wei Liu,
Vsevolod Ivanov,
Kaushalya Jhuria,
Qing Ji,
Arun Persaud,
Walid Redjem,
Jacopo Simoni,
Yertay Zhiyenbayev,
Boubacar Kante,
Javier Garcia Lopez,
Liang Z. Tan,
Thomas Schenkel
Abstract:
Near infrared color centers in silicon are emerging candidates for on-chip integrated quantum emitters, optical access quantum memories and sensing. We access ensemble G color center formation dynamics and radiation-induced atomic disorder in silicon for a series of MeV proton flux conditions. Photoluminescence results reveal that the G-centers are formed more efficiently by pulsed proton irradiat…
▽ More
Near infrared color centers in silicon are emerging candidates for on-chip integrated quantum emitters, optical access quantum memories and sensing. We access ensemble G color center formation dynamics and radiation-induced atomic disorder in silicon for a series of MeV proton flux conditions. Photoluminescence results reveal that the G-centers are formed more efficiently by pulsed proton irradiation than continuous wave proton irradiation. The enhanced transient excitations and dynamic annealing within nanoseconds allows optimizing the ratio of G-center formation to nonradiative defect accumulation. The G-centers preserve narrow linewidths of about 0.1 nm when they are generated by moderate pulsed proton fluences, while the linewidth broadens significantly as the pulsed proton fluence increases. This implies vacancy/interstitial clustering by overlapping collision cascades. Tracking G-center properties for a series of irradiation conditions enables sensitive probing of atomic disorder, serving as a complimentary analytical method for sensing damage accumulation. Aided by ${\it ab}$ ${\it initio}$ electronic structure calculations, we provide insight into the atomic disorder-induced inhomogeneous broadening by introducing vacancies and silicon interstitials in the vicinity of a G-center. A vacancy leads to a tensile strain and can result in either a redshift or blueshift of the G-center emission, depending on its position relative to the G-center. Meanwhile, Si interstitials lead to compressive strain, which results in a monotonic redshift. High flux and tunable ion pulses enable the exploration of fundamental dynamics of radiation-induced defects as well as methods for defect engineering and qubit synthesis for quantum information processing.
△ Less
Submitted 11 February, 2023;
originally announced February 2023.
-
Disordered topological graphs enhancing nonlinear phenomena
Authors:
Zhetao Jia,
Matteo Seclì,
Alexander Avdoshkin,
Walid Redjem,
Elizabeth Dresselhaus,
Joel Moore,
Boubacar Kanté
Abstract:
Complex networks play a fundamental role in understanding phenomena from the collective behavior of spins, neural networks, and power grids to the spread of diseases. Topological phenomena in such networks have recently been exploited to preserve the response of systems in the presence of disorder. We propose and demonstrate topological structurally disordered systems with a modal structure that e…
▽ More
Complex networks play a fundamental role in understanding phenomena from the collective behavior of spins, neural networks, and power grids to the spread of diseases. Topological phenomena in such networks have recently been exploited to preserve the response of systems in the presence of disorder. We propose and demonstrate topological structurally disordered systems with a modal structure that enhances nonlinear phenomena in the topological channels by inhibiting the ultrafast leakage of energy from edge modes to bulk modes. We present the construction of the graph and show that its dynamics enhances the topologically protected photon pair generation rate by an order of magnitude. Disordered nonlinear topological graphs will enable advanced quantum interconnects, efficient nonlinear sources, and light-based information processing for artificial intelligence.
△ Less
Submitted 11 May, 2023; v1 submitted 23 November, 2022;
originally announced November 2022.
-
Effect of Localization on Photoluminescence and Zero-Field Splitting of Silicon Color Centers
Authors:
Vsevolod Ivanov,
Jacopo Simoni,
Yeonghun Lee,
Wei Liu,
Kaushalya Jhuria,
Walid Redjem,
Yertay Zhiyenbayev,
Christos Papapanos,
Wayesh Qarony,
Boubacar Kante,
Arun Persaud,
Thomas Schenkel,
Liang Z. Tan
Abstract:
The study of defect centers in silicon has been recently reinvigorated by their potential applications in optical quantum information processing. A number of silicon defect centers emit single photons in the telecommunication $O$-band, making them promising building blocks for quantum networks between computing nodes. The two-carbon G-center, self-interstitial W-center, and spin-$1/2$ T-center are…
▽ More
The study of defect centers in silicon has been recently reinvigorated by their potential applications in optical quantum information processing. A number of silicon defect centers emit single photons in the telecommunication $O$-band, making them promising building blocks for quantum networks between computing nodes. The two-carbon G-center, self-interstitial W-center, and spin-$1/2$ T-center are the most intensively studied silicon defect centers, yet despite this, there is no consensus on the precise configurations of defect atoms in these centers, and their electronic structures remain ambiguous. Here we employ \textit{ab initio} density functional theory to characterize these defect centers, providing insight into the relaxed structures, bandstructures, and photoluminescence spectra, which are compared to experimental results. Motivation is provided for how these properties are intimately related to the localization of electronic states in the defect centers. In particular, we present the calculation of the zero-field splitting for the excited triplet state of the G-center defect as the structure is transformed from the A-configuration to the B-configuration, showing a sudden increase in the magnitude of the $D_{zz}$ component of the zero-field splitting tensor. By performing projections onto the local orbital states of the defect, we analyze this transition in terms of the symmetry and bonding character of the G-center defect which sheds light on its potential application as a spin-photon interface.
△ Less
Submitted 23 September, 2022; v1 submitted 9 June, 2022;
originally announced June 2022.
-
Defect engineering of silicon with ion pulses from laser acceleration
Authors:
Walid Redjem,
Ariel J. Amsellem,
Frances I. Allen,
Gabriele Benndorf,
Jianhui Bin,
Stepan Bulanov,
Eric Esarey,
Leonard C. Feldman,
Javier Ferrer Fernandez,
Javier Garcia Lopez,
Laura Geulig,
Cameron R. Geddes,
Hussein Hijazi,
Qing Ji,
Vsevolod Ivanov,
Boubacar Kante,
Anthony Gonsalves,
Jan Meijer,
Kei Nakamura,
Arun Persaud,
Ian Pong,
Lieselotte Obst-Huebl,
Peter A. Seidl,
Jacopo Simoni,
Carl Schroeder
, et al. (5 additional authors not shown)
Abstract:
Defect engineering is foundational to classical electronic device development and for emerging quantum devices. Here, we report on defect engineering of silicon single crystals with ion pulses from a laser accelerator with ion flux levels up to 10^22 ions/cm^2/s. Low energy ions from plasma expansion of the laser-foil target are implanted near the surface and then diffuse into silicon samples that…
▽ More
Defect engineering is foundational to classical electronic device development and for emerging quantum devices. Here, we report on defect engineering of silicon single crystals with ion pulses from a laser accelerator with ion flux levels up to 10^22 ions/cm^2/s. Low energy ions from plasma expansion of the laser-foil target are implanted near the surface and then diffuse into silicon samples that were locally pre-heated by high energy ions. We observe low energy ion fluences of ~10^16 cm^-2, about four orders of magnitude higher than the fluence of high energy (MeV) ions. In the areas of highest energy deposition, silicon crystals exfoliate from single ion pulses. Color centers, predominantly W and G-centers, form directly in response to ion pulses without a subsequent annealing step. We find that the linewidth of G-centers increase in areas with high ion flux much more than the linewidth of W-centers, consistent with density functional theory calculations of their electronic structure. Laser ion acceleration generates aligned pulses of high and low energy ions that expand the parameter range for defect engineering and doping of semiconductors with tunable balances of ion flux, damage rates and local heating.
△ Less
Submitted 25 March, 2022;
originally announced March 2022.
-
Active topological photonics
Authors:
Yasutomo Ota,
Kenta Takata,
Tomoki Ozawa,
Alberto Amo,
Zhetao Jia,
Boubacar Kante,
Masaya Notomi,
Yasuhiko Arakawa,
Satoshi Iwamoto
Abstract:
Topological photonics has emerged as a novel route to engineer the flow of light. Topologically-protected photonic edge modes, which are supported at the perimeters of topologically-nontrivial insulating bulk structures, have been of particular interest as they may enable low-loss optical waveguides immune to structural disorder. Very recently, there is a sharp rise of interest in introducing gain…
▽ More
Topological photonics has emerged as a novel route to engineer the flow of light. Topologically-protected photonic edge modes, which are supported at the perimeters of topologically-nontrivial insulating bulk structures, have been of particular interest as they may enable low-loss optical waveguides immune to structural disorder. Very recently, there is a sharp rise of interest in introducing gain materials into such topological photonic structures, primarily aiming at revolu-tionizing semiconductor lasers with the aid of physical mechanisms existing in topological physics. Examples of re-markable realizations are topological lasers with unidirectional light output under time-reversal symmetry breaking and topologically-protected polariton and micro/nano-cavity lasers. Moreover, the introduction of gain and loss provides a fascinating playground to explore novel topological phases, which are in close relevance to non-Hermitian and parity-time symmetric quantum physics and are in general difficult to access using fermionic condensed matter systems. Here, we review the cutting-edge research on active topological photonics, in which optical gain plays a pivotal role. We discuss recent realizations of topological lasers of various kinds, together with the underlying physics explaining the emergence of topological edge modes. In such demonstrations, the optical modes of the topological lasers are deter-mined by the dielectric structures and support lasing oscillation with the help of optical gain. We also address recent researches on topological photonic systems in which gain and loss themselves essentially influence on topological prop-erties of the bulk systems. We believe that active topological photonics provides powerful means to advance mi-cro/nanophotonics systems for diverse applications and topological physics itself as well.
△ Less
Submitted 11 December, 2019; v1 submitted 11 December, 2019;
originally announced December 2019.