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22 Apr 2022 • Journal Article • Journal of Physics A: Mathematical and Theoretical
Tuning quantum-classical correspondence for atomic and molecular systems in a cavity
AbstractWe show that the correspondence between quantum and classical mechanics can be tuned by varying the coupling strength between an atom or a molecule and the modes of a cavity. In the acceleration gauge (AG) representation, the cavity-matter system is described by an effective Hamiltonian, with a non-trivial coupling appearing in the potential, and with renormalized masses
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15 Apr 2022 • Journal Article • Communications in Mathematical Physics
Entanglement Subvolume Law for 2D Frustration-Free Spin Systems
AbstractLet H be a frustration-free Hamiltonian describing a 2D grid of qudits with local interactions, a unique ground state, and local spectral gap lower bounded by a positive constant. For any bipartition defined by a vertical cut of length L running from top to bottom of the grid, we prove that the corresponding entanglement entropy of the ground state of H is upper bounded
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11 Apr 2022 • Preprint • arXiv
Phonon-induced modification of quantum criticality
AbstractWe study the effect of acoustic phonons on the quantum phase transition in the O($N$) model. We develop a renormalization group analysis near (3+1) space-time dimensions and derive the RG equations using an $\epsilon$-expansion. Our results indicate that when the number of flavors of the underlying O($N$) model exceeds a critical number $N_c=4$, the quantum transition
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11 Apr 2022 • Journal Article • SciPost Physics
Proposal for realizing anomalous Floquet insulators via Chern band annihilation
AbstractTwo-dimensional periodically driven systems can host an unconventional topological phase unattainable for equilibrium systems, termed the Anomalous Floquet-Anderson insulator (AFAI). The AFAI features a quasi-energy spectrum with chiral edge modes and a fully localized bulk, leading to non-adiabatic but quantized charge pumping. Here, we show how such a Floquet phase
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6 Apr 2022 • Preprint • arXiv
Towards a controllable SQUID
AbstractJosephson junctions and superconducting quantum interference devices (SQUID) are important electronic elements, which are based on normal conductor sandwiched between two superconductors. These junctions are produced by evaporation techniques, and once they are embedded in an electronic circuit, their properties are fixed. Using SQUIDs as a tunable component requires
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1 Apr 2022 • Conference Paper • Physics and Simulation of Optoelectronic Devices XXX
Dynamic filtering and modulation properties of tunnel-injection based quantum-dot laser devices
AbstractWe show via a combination of material realistic quantum-kinetic theory and experimental differential pump-probe results, that performance issues in tunnel-injection QD lasers are caused by a filtering effect, resulting from the hybridization of different QD shells with the injector quantum well. The real footprint of applicability in optical communication system is the
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1 Apr 2022 • Journal Article • Semiconductor Science and Technology
High optical gain in InP-based quantum-dot material monolithically grown on silicon emitting at telecom wavelengths
AbstractWe describe the fabrication process and properties of an InP based quantum dot laser structure grown on a 5° off-cut silicon substrate. Several layers of quantum dot based dislocation filters embedded in GaAs and InP were used to minimize the defect density in the quantum dot active region which comprised eight emitting dot layers. The structure was analyzed using high
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1 Apr 2022 • Journal Article • Journal of Applied Physics
Light-induced trap emptying revealed by intensity-dependent quantum efficiency of organic solar cells
AbstractRevisiting the intensity-dependent quantum efficiency (IDQE) technique in the context of non-fullerene acceptors, we find that at forward-bias conditions, the response exhibits what seems to be anomalous behavior that is not consistent with light excitation induced trap filling. Analysis based on the Shockley–Read–Hall model leads to the conclusion that the contacts
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31 Mar 2022 • Journal Article • The Journal of Physical Chemistry C
Explanation of the Opposing Shifts in the Absorption Edge and the Optical Resonance in CuFeS2 Nanoparticles
AbstractSize-dependent change of the electronic band structure is one of the key features of nanoparticles in the quantum confinement region. CuFeS2 nanoparticles have a strong absorption feature in the visible region that has, controversially, been described as neither an excitonic transition nor a free carrier plasmon oscillation. Instead, the absorption feature in CuFeS2
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26 Mar 2022 • Preprint • arXiv
Room-temperature strong coupling at the nanoscale achieved by inverse design
AbstractRoom-temperature strong coupling between plasmonic nanocavities and monolayer semiconductors is a prominent path towards efficient, integrated light-matter interactions. However, designing such systems is challenging due to the nontrivial dependence of the strong coupling on various properties of the cavity and emitter, as well as the subwavelength scale of the interaction
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24 Mar 2022 • Journal Article • Physical Review Letters
Enhanced Cooper-Pair Injection into a Semiconductor Structure by Resonant Tunneling
AbstractWe demonstrate enhanced Andreev reflection in a -based superconductor-semiconductor hybrid device resulting in increased Cooper-pair injection efficiency, achieved by Cooper-pair tunneling into a semiconductor quantum well resonant state. We show this enhancement by
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23 Mar 2022 • Journal Article • Npj Quantum Information
Free electrons can induce entanglement between photons
AbstractEntanglement of photons is a fundamental feature of quantum mechanics, which stands at the core of quantum technologies such as photonic quantum computing, communication, and sensing. An ongoing challenge in all these is finding an efficient and controllable mechanism to entangle photons. Recent experimental developments in electron microscopy enable to control the
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22 Mar 2022 • Journal Article • The Journal of Chemical Physics
Ultrafast Vibrational Excitation Transfer on Resonant Antenna Lattices Revealed by Two-Dimensional Infrared Spectroscopy
AbstractHigh-quality lattice resonances in arrays of infrared antennas operating in an open-cavity regime form polariton states by means of strong coupling to molecular vibrations. We studied polaritons formed by carbonyl stretching modes of (poly)methyl methacrylate on resonant antenna arrays using femtosecond 2DIR spectroscopy. At a normal incidence of excitation light
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18 Mar 2022 • Conference Paper • APS March Meeting 2022
Canonical phase measurement enabled by quantum feedback control
AbstractIn addition to extracting information, measurements of quantum systems are a resource for enhancing control and precision. They can be used to alter what we are detecting and allow access to new observables. Current hardware can perform near-ideal measurements of photon number or field amplitude, the ability to perform an ideal phase measurement is still lacking, even
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18 Mar 2022 • Conference Paper • APS March Meeting 2022
Observation of intrinsic topological superconductivity in transition metal dichalcogenide
AbstractTopological superconductors may harbor non-Abelian excitation on its boundaries such as Majorana zero mode – an essential ingredient for quantum information processing. Although, Majorana edge mode has been observed in several hybrid heterostructures and epitaxially grown materials, it is yet to be demonstrated in a layered stoichiometric material. This is essential to
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17 Mar 2022 • Conference Paper • APS March Meeting 2022
Reducing cavity-qubit operation times with antisymmetric pulses for bosonic codes
AbstractBosonic encoding is a nascent robust path to quantum computation, allowing error correction already at the hardware level. For an oscillator dispersively coupled to a two level ancilla, the universal control required for computation with any bosonic code was shown to be possible. However, the rate of control of such systems, as realized by Transmon coupled to a long-lived
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16 Mar 2022 • Conference Paper • APS March Meeting 2022
Coherent Non-Local Subspace Dynamics Induced by Zeno Measurements
AbstractWe describe how an entangling operation related to a CPHASE gate may be implemented by drawing on unique features of quantum measurement. The dynamics of a quantum system can be frozen by sufficiently strong monitoring, i.e., by the quantum Zeno effect. We show here that it is possible to combine local unitary operations and Zeno blocking of a single transition within
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16 Mar 2022 • Conference Paper • APS March Meeting 2022
Effect of acoustic phonons on quantum criticality
AbstractWe study the fate of quantum criticality in a spin system coupled to gapless phonons. In one dimension, a recent study based on renormalization group (RG) analysis and density matrix renormalization group (DMRG) calculations reveals the possibility of the transition to remain second-order or driven to first-order, depending on the ratio of velocities of the spins and
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15 Mar 2022 • Preprint • arXiv
Algorithmic cooling for resolving state preparation and measurement errors in quantum computing
AbstractState preparation and measurement errors are commonly regarded as indistinguishable. The problem of distinguishing state preparation (SPAM) errors from measurement errors is important to the field of characterizing quantum processors. In this work, we propose a method to separately characterize SPAM errors using a novel type of algorithmic cooling protocol called
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15 Mar 2022 • Conference Paper • APS March Meeting 2022
Critical excitonic mode interacting with phonons in excitonic insulator Ta2Ni(Se1−xSx)5
AbstractExcitonic insulator is a quantum coherent phase resulting from formation of a macroscopic population of electron-hole pairs. For a semimetal with narrow overlap of the conduction and valence bands, a finite exciton binding energy could lead to excitonic instability. Candidate material Ta2NiSe5 shows a second-order structural phase transition at Tc=328K, with two mirror
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13 Mar 2022 • Journal Article • Advanced Science
Edge State Quantum Interference in Twisted Graphitic Interfaces
AbstractZigzag edges in graphitic systems exhibit localized electronic states that drastically affect their properties. Here, room-temperature charge transport experiments across a single graphitic interface are reported, in which the interlayer current is confined to the contact edges. It is shown that the current exhibits pronounced oscillations of up to ≈40 µA with a dominant
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11 Mar 2022 • Journal Article • Journal of Physics D: Applied Physics
Encircling exceptional points of Bloch waves: mode conversion and anomalous scattering
AbstractThe normal modes of nonconservative systems coalesce at the so-called exceptional points (EPs) of their spectrum. These degeneracy points are the source of unusual phenomena, some of which are accessed by encircling the points in a suitable space. Here, we encircle the EPs of the transfer matrix of a periodic laminate, using a spatial perturbation in its stiffness. We
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10 Mar 2022 • Conference Paper • 2022 Optical Fiber Communications Conference and Exhibition (OFC)
1.5-µm Indium Phosphide-based Quantum Dot Lasers and Optical Amplifiers
AbstractAn overview will be given on the progress of quantum dot laser materials addressing the telecom C band and their high potential for the application in optical communication systems, where temperature stability of the device performance as well as a narrow linewidth emission plays an important role. Device results of quantum dot lasers and optical amplifiers will be
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8 Mar 2022 • Journal Article • Physical Review A
Comment on “Nonlinear quantum effects in electromagnetic radiation of a vortex electron”
AbstractThis comment on the paper by Karlovets and Pupasov-Maksimov [Phys. Rev. A 103, 012214 (2021)] addresses their criticism of the combined experimental and theoretical study by Remez et al. [Phys. Rev. Lett. 123, 060401 (2019)]. We show, by means of simple optical arguments as well as numerical simulations, that the arguments raised by Karlovets and Pupasov-Maksimov
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3 Mar 2022 • Journal Article • Physical Review X
Absence of Heating in a Uniform Fermi Gas Created by Periodic Driving
AbstractUltracold atomic gas provides a useful tool to explore many-body physics. One of the recent additions to this experimental toolbox is Floquet engineering, where periodic modulation of the Hamiltonian allows the creation of effective potentials that do not exist otherwise. When subject to external modulations, however, generic interacting many-body systems absorb energy
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3 Mar 2022 • Preprint • arXiv
Observation of 2D Cherenkov radiation
AbstractFor over 80 years of research, the conventional description of free-electron radiation phenomena, such as Cherenkov radiation, has remained unchanged: classical three-dimensional electromagnetic waves. Interestingly, in reduced dimensionality, the properties of free-electron radiation are predicted to fundamentally change. Here, we present the first observation of
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2 Mar 2022 • Preprint • arXiv
Universal transport in periodically driven systems without long-lived quasiparticles
AbstractAn intriguing regime of universal charge transport at high entropy density has been proposed for periodically driven interacting one-dimensional systems with Bloch bands separated by a large single-particle band gap. For weak interactions, a simple picture based on well-defined Floquet quasiparticles suggests that the system should host a quasisteady state current that
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24 Feb 2022 • Journal Article • Physical Review A
Spectroscopy on the electron-electric-dipole-moment–sensitive states of
AbstractAn excellent candidate molecule for the measurement of the electron's electric dipole moment (eEDM) is thorium monofluoride ( ) because the eEDM–sensitive state, , is the electronic ground state, and thus is immune to
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21 Feb 2022 • Preprint • arXiv
Interplay of superconductivity and dissipation in quantum Hall edges
AbstractSystems harboring parafermion zero-modes hold promise as platforms for topological quantum computation. Recent experimental work (G\"{u}l et al., arXiv:2009.07836) provided evidence for proximity-induced superconductivity in fractional quantum Hall edges, a prerequisite in proposed realizations of parafermion zero-modes. The main evidence was the observation of a crossed
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7 Feb 2022 • Journal Article
Light emission by free electrons in photonic time-crystals
AbstractPhotonic time-crystals (PTCs) are spatially homogeneous media whose electromagnetic susceptibility varies periodically in time, causing temporal reflections and refractions for any wave propagating within the medium. The time-reflected and time-refracted waves interfere, giving rise to Floquet modes with momentum bands separated by momentum gaps (rather than energy
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2 Feb 2022 • Journal Article • The Journal of Chemical Physics
Temperature dependence of Fano resonances in CrPS4
AbstractA Fano resonance, as often observed in scattering, absorption, or transmission experiments, arises from quantum interference between a discrete optical transition and a continuous background. Here, we present a temperature-dependent study on Fano resonances observed in photoluminescence from flakes of the layered semiconductor antiferromagnet chromium thiophosphate
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31 Jan 2022 • Journal Article • Physical Review Research
Correlation-enhanced neural networks as interpretable variational quantum states
AbstractVariational methods have proven to be excellent tools to approximate the ground states of complex many-body Hamiltonians. Generic tools such as neural networks are extremely powerful, but their parameters are not necessarily physically motivated. Thus, an efficient parametrization of the wave function can become challenging. In this Letter we introduce a neural-network-based
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28 Jan 2022 • Preprint • arXiv
Amplified Emission by Atoms and Lasing in Photonic Time Crystals
AbstractPhotonic Time Crystals (PTCs) - dielectric media with their refractive index modulated periodically in time, offer new opportunities in photonics arising from time reflections and momentum bandgaps. Here, we study the emission of light from a radiation source inside a PTC. We solve the general classical and quantum mechanical models of emission in a temporally-varying
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28 Jan 2022 • Journal Article • Entropy
Digital Signatures with Quantum Candies
AbstractQuantum candies (qandies) represent a type of pedagogical simple model that describes many concepts from quantum information processing (QIP) intuitively without the need to understand or make use of superpositions and without the need of using complex algebra. One of the topics in quantum cryptography that has gained research attention in recent years is quantum
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20 Jan 2022 • Journal Article • Nano Futures
Dynamics of light-induced charge transfer between carbon nanotube and CdSe/CdS core/shell nanocrystals
AbstractThe integration of semiconducting colloidal nanocrystals (NCs) with carbon nanotubes (CNTs) in a single device presents a unique platform that combines optical flexibility with high charge carrying capability. These qualities are desirable in many applications such as photovoltaic cells, photocatalysis, and light sensors. Here, we present hybrid devices that incorporate
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18 Jan 2022 • Journal Article • Physical Review B
Quantum measurement with recycled photons
AbstractWe study a device composed of an optical interferometer integrated with a ferrimagnetic sphere resonator (FSR). Magneto-optic coupling can be employed in such a device to manipulate entanglement between optical pulses that are injected into the interferometer and the FSR. The device is designed to allow measuring the lifetime of such macroscopic entangled states in the
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14 Jan 2022 • Journal Article • Physical Review B
Spin purity of the quantum dot confined electron and hole in an external magnetic field
AbstractWe investigate experimentally and theoretically the temporal evolution of the spin of the conduction band electron and that of the valence band heavy hole, both confined in the same semiconductor quantum dot. We use all-optical pulse techniques to perform complete tomographic measurements of the spin as a function of time after its initialization and study the total
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4 Jan 2022 • Journal Article • Physical Review Letters
Enhanced Coupling of Electron and Nuclear Spins by Quantum Tunneling Resonances
AbstractNoble-gas spins feature hours-long coherence times, owing to their great isolation from the environment, and find practical usage in various applications. However, this isolation leads to extremely slow preparation times, relying on weak spin transfer from an electron-spin ensemble. Here we propose a controllable mechanism to enhance this transfer rate. We analyze the
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Jan 2022 • Journal Article • Progress in Quantum Electronics
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Jan 2022 • Journal Article • Annalen Der Physik
Spin-Spacetime Censorship
AbstractQuantum entanglement and relativistic causality are key concepts in theoretical works seeking to unify quantum mechanics and gravity. In this article, a gedanken experiment that couples the spin to spacetime is proposed, and is then analyzed in the context of quantum information by using different approaches to quantum gravity. Both classical gravity theory and certain
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23 Dec 2021 • Journal Article • Journal of Statistical Mechanics: Theory and Experiment
Uncertainty relations for mesoscopic coherent light
AbstractThermodynamic uncertainty relations unveil useful connections between fluctuations in thermal systems and entropy production. This work extends these ideas to the disparate field of zero temperature quantum mesoscopic physics where fluctuations are due to coherent effects and entropy production is replaced by a cost function. The cost function arises naturally as a
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20 Dec 2021 • Preprint • arXiv
Practical Quantum State Tomography for Gibbs states
AbstractQuantum state tomography is an essential tool for the characterization and verification of quantum states. However, as it cannot be directly applied to systems with more than a few qubits, efficient tomography of larger states on mid-sized quantum devices remains an important challenge in quantum computing. We develop a tomography approach that requires moderate
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15 Dec 2021 • Journal Article • Physical Review Letters
Towards an Independent Determination of Muon from Muonium Spectroscopy
AbstractWe show that muonium spectroscopy in the coming years can reach a precision high enough to determine the anomalous magnetic moment of the muon below one part per million (ppm). Such an independent determination of muon would certainly shed light on the difference currently
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10 Dec 2021 • Journal Article • Physical Review B
Failed excitonic quantum phase transition in
AbstractWe study the electronic phase diagram of the excitonic insulator candidates
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6 Dec 2021 • Conference Paper • 2021 IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems (COMCAS)
Interaction of Microwave Coupled Ferrimagnetic Sphere with Figure-8 Laser
AbstractCoupling both optical light and microwave with magnetic materials is a pursued area of research recently as it will lead to emerging quantum technologies. Although spin waves in magnetic materials can be strongly coupled to microwave radiation, effective coupling of optical light with spin wave in magnetic system is still a major challenge. We have set up a figure-8
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1 Dec 2021 • Journal Article • Physical Review X
Quantum Nature of Dielectric Laser Accelerators
AbstractDielectric laser accelerators (DLAs) hold great promise for producing economic and compact on-chip radiation sources. On-chip DLAs benefit from fabrication capabilities of the silicon industry and from breakthroughs in silicon-photonic nanostructures to enhance the interaction between particles and laser fields. Seemingly unrelated recent advances in the quantum
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26 Nov 2021 • Conference Paper • 2021 27th International Semiconductor Laser Conference (ISLC)
Quantum coherent revival in a room-temperature quantum-dot optical amplifier: a route towards practical quantum information processing
AbstractThe hallmark quantum-optics phenomenon: quantum coherent revival was demonstrated in room-temperature quantum dot optical amplifiers. The revival originates from coherent excitation of, and interaction among, homogeneous subgroups within an inhomogeneous ensemble, which play the role of a multi qubits platform for practical quantum information processing.
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23 Nov 2021 • Preprint • arXiv
Quantum information and beyond--with quantum candies
AbstractThe field of quantum information is becoming more known to the general public. However, effectively demonstrating the concepts underneath quantum science and technology to the general public can be a challenging job. We investigate, extend, and greatly expand here "quantum candies" (invented by Jacobs), a pedagogical model for intuitively describing some basic concepts
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15 Nov 2021 • Journal Article • The Journal of Physical Chemistry C
Room Temperature Colloidal Coating of II–VI Nanoplatelets with Quantum Dots
AbstractThe low-temperature colloidal production of II–VI nanoplatelet heterostructures has stimulated the interest of researchers due to the possible uses of these materials in various optoelectronic devices. Here, we report a room-temperature coating by CdS or ZnS dots of preprepared CdSe nanoplatelets. The dot coating process made use of a synthesis developed for the formation
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13 Nov 2021 • Preprint • arXiv
Fock lasers based on deep-strong coupling of light and matter
AbstractLight and matter can now interact in a regime where their coupling is stronger than their bare energies. This deep-strong coupling (DSC) regime of quantum electrodynamics promises to challenge many conventional assumptions about the physics of light and matter. Here, we show how light and matter interactions in this regime give rise to electromagnetic nonlinearities
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5 Nov 2021 • Journal Article • Physical Review A
Quantum advantage and noise reduction in distributed quantum computing
AbstractDistributed quantum computing can provide substantial noise reduction due to shallower circuits. An experiment illustrates the advantages in the case of a Grover search. This motivates study of the quantum advantage of the distributed version of the Simon and Deutsch-Jozsa algorithms. We show that the distributed Simon algorithm retains the exponential advantage, but
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25 Oct 2021 • Journal Article • Nature Physics
Evidence of topological boundary modes with topological nodal-point superconductivity Associated Content
AbstractTopological superconductors are an essential component for topologically protected quantum computation and information processing. Although signatures of topological superconductivity have been reported in heterostructures, material realizations of intrinsic topological superconductors are rather rare. Here we use scanning tunnelling spectroscopy to study the transition
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20 Oct 2021 • Preprint • arXiv
The mean field approximation and disentanglement
AbstractThe mean field approximation becomes applicable when entanglement is sufficiently weak. We explore a nonlinear term that can be added to the Schrödinger equation without violating unitarity of the time evolution. We find that the added term suppresses entanglement, without affecting the evolution of any product state. The dynamics generated by the modified Schrödinger
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12 Oct 2021 • Preprint • arXiv
A deterministic source of indistinguishable photons in a cluster state
AbstractMeasurement-based quantum communication relies on the availability of highly entangled multi-photon cluster states. The inbuilt redundancy in the cluster allows communication between remote nodes using repeated local measurements, compensating for photon losses and probabilistic Bell-measurements. For feasible applications, the cluster generation should be fast
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7 Oct 2021 • Preprint • arXiv
Generalized Fresnel-Floquet equations for driven quantum materials
AbstractOptical drives at terahertz and mid-infrared frequencies in quantum materials are increasingly used to reveal the nonlinear dynamics of collective modes in correlated many-body systems and their interplay with electromagnetic waves. Recent experiments demonstrated several surprising optical properties of transient states induced by driving, including the appearance of
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7 Oct 2021 • Journal Article • Npj Computational Materials
Method for assessing atomic sources of flicker noise in superconducting qubits
AbstractFlicker noise causes decoherence in Josephson junction-based superconducting qubits, thus limiting their practical potential as building blocks for quantum computers. This is due to limited length and complexity of executable algorithms, and increased dependency on error-correcting measures. Therefore, identifying and subsiding the atomic sources of flicker noise are
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4 Oct 2021 • Preprint • arXiv
Mode coupling, bi-stability, and spectral broadening in buckled nanotube resonators
AbstractBi-stable mechanical resonators play a significant role in various applications, such as sensors, memory elements, and quantum computing. While carbon nanotube (CNT) based resonators have been widely investigated as promising nano electro-mechanical devices, a bi-stable CNT resonator has never been demonstrated. Here, we report a new class of CNT resonators in which
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30 Sep 2021 • Preprint • arXiv
Illustrating quantum information with quantum candies
AbstractThe field of quantum information is becoming more known to the general public. However, effectively demonstrating the concepts underneath quantum science and technology to the general public can be a challenging job. We investigate, extend, and much expand here "quantum candies" (invented by Jacobs), a pedagogical model for intuitively describing some basic concepts in
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30 Sep 2021 • Journal Article • Applied Physics Letters
Prospects in x-ray science emerging from quantum optics and nanomaterials
AbstractThe science of x-rays is by now over 125 years old, starting with Wilhelm Röntgen's discovery of x-rays in 1895, for which Röntgen was awarded the first Nobel Prize in Physics. X-rays have fundamentally changed the world in areas, including medical imaging, security scanners, industrial inspection, materials development, and drugs spectroscopy. X-ray science has been
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18 Sep 2021 • Quantum Dot Photodetectors
Two-Dimensional Material-Based Quantum Dots for Wavelength-Selective, Tunable, and Broadband Photodetector Devices
AbstractThe rise of atomically thin two-dimensional (2D) materials brings a revolution in material science and engineering, and encouraged worldwide scientists to integrate desired 2D materials into electrical circuitry by non-covalent interactions. Regardless of some unique properties including super-flexibility, broadband absorption and high carrier mobility, the weak optical
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17 Sep 2021 • Journal Article • New Journal of Physics
Selection rules for breaking selection rules
AbstractFloquet systems often exhibit dynamical symmetries (DS) that govern the time-dependent dynamics and result in selection rules. When a DS is broken, selection rule deviations are expected. Typically, information about the symmetry-breaking perturbation/phase and the time-dependent dynamics can be extracted from these deviations, hence they are regarded as a background
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13 Sep 2021 • Journal Article • Applied Physics Letters
Nonvolatile voltage-tunable ferroelectric-superconducting quantum interference memory devices
AbstractSuperconductivity serves as a unique solid-state platform for electron interference at a device-relevant lengthscale, which is essential for quantum information and sensing technologies. As opposed to semiconducting transistors that are operated by voltage biasing at the nanometer scale, superconductive quantum devices cannot sustain voltage and are operated with magnetic
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6 Sep 2021 • Journal Article • Nature Communications
Electronic Floquet gyro-liquid crystal
AbstractFloquet engineering uses coherent time-periodic drives to realize designer band structures on-demand, thus yielding a versatile approach for inducing a wide range of exotic quantum many-body phenomena. Here we show how this approach can be used to induce non-equilibrium correlated states with spontaneously broken symmetry in lightly doped semiconductors. In the presence
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30 Aug 2021 • Journal Article • Molecules
Variational Solutions for Resonances by a Finite-Difference Grid Method
AbstractWe demonstrate that the finite difference grid method (FDM) can be simply modified to satisfy the variational principle and enable calculations of both real and complex poles of the scattering matrix. These complex poles are known as resonances and provide the energies and inverse lifetimes of the system under study (e.g., molecules) in metastable states. This approach
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26 Aug 2021 • Journal Article • Science
Imprinting the quantum statistics of photons on free electrons
AbstractThe interaction between free electrons and light stands at the base of both classical and quantum physics, with applications in free-electron acceleration, radiation sources, and electron microscopy. Yet to this day, all experiments involving free-electron–light interactions are fully explained by describing the light as a classical wave. We observed quantum statistics
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25 Aug 2021 • Journal Article • Physical Review Letters
Synthetic-Space Photonic Topological Insulators Utilizing Dynamically Invariant Structure
AbstractSynthetic-space topological insulators are topological systems with at least one spatial dimension replaced by a periodic arrangement of modes, in the form of a ladder of energy levels, cavity modes, or some other sequence of modes. Such systems can significantly enrich the physics of topological insulators, in facilitating higher dimensions, nonlocal coupling, and more
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22 Aug 2021 • Journal Article • Entropy
The Problem of Engines in Statistical Physics
AbstractEngines are open systems that can generate work cyclically at the expense of an external disequilibrium. They are ubiquitous in nature and technology, but the course of mathematical physics over the last 300 years has tended to make their dynamics in time a theoretical blind spot. This has hampered the usefulness of statistical mechanics applied to active systems
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19 Aug 2021 • Preprint • arXiv
Demonstration of an entangling gate between non-interacting qubits using the Quantum Zeno effect
AbstractThe Zeno effect occurs in quantum systems when a very strong measurement is applied, which can alter the dynamics in non-trivial ways. Despite being dissipative, the dynamics stay coherent within any degenerate subspaces of the measurement. Here we show that such a measurement can turn a single-qubit operation into a two- or multi-qubit entangling gate, even in a
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19 Aug 2021 • Preprint • arXiv
Optimal short-time measurements for Hamiltonian learning
AbstractCharacterizing noisy quantum devices requires methods for learning the underlying quantum Hamiltonian which governs their dynamics. Often, such methods compare measurements to simulations of candidate Hamiltonians, a task which requires exponential computational complexity. Here, we analyze and optimize a method which circumvents this difficulty using measurements of
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15 Aug 2021 • Preprint • arXiv
On the carrier transport and radiative recombination mechanisms in tunneling injection quantum dot lasers
AbstractWe report temperature-dependent current-voltage (I - V - T) and output light power-voltage or current (P - V - T) or (P - I - T) characteristics of 1550 nm tunneling injection quantum dot (TI QD) laser diodes. Experimental data is accompanied by physical models that distinguish between different current flow and light emission mechanisms for different applied voltages
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12 Aug 2021 • Preprint • arXiv
Quantum tomography of entangled spin-multi-photon states
AbstractWe present a novel method for quantum tomography of multi-qubit states. We apply the method to spin-multi-photon states, which we produce by periodic excitation of a semiconductor quantum-dot- confined spin every 1/4 of its coherent precession period. These timed excitations lead to the deterministic generation of strings of entangled photons in a cluster state. We show
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11 Aug 2021 • Journal Article • Science Advances
Orbital angular momentum multiplication in plasmonic vortex cavities
AbstractOrbital angular momentum of light is a core feature in photonics. Its confinement to surfaces using plasmonics has unlocked many phenomena and potential applications. Here, we introduce the reflection from structural boundaries as a new degree of freedom to generate and control plasmonic orbital angular momentum. We experimentally demonstrate plasmonic vortex cavities
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5 Aug 2021 • Journal Article • Physical Review Letters
Superradiance and Subradiance due to Quantum Interference of Entangled Free Electrons
AbstractWhen multiple quantum emitters radiate, their emission rate may be enhanced or suppressed due to collective interference in a process known as super- or subradiance. Such processes are well known to occur also in light emission from free electrons, known as coherent cathodoluminescence. Unlike atomic systems, free electrons have an unbounded energy spectrum, and, thus
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30 Jul 2021 • Conference Paper • Microscopy and Microanalysis
Extreme Light-Matter Interactions in the Ultrafast Transmission Electron Microscope
AbstractOver the past few years, quantized interactions between coherent free electrons and femtosecond laser pulses have shown intriguing new prospects for light-matter interactions. The talk will present theory and experiments of free electrons in laser-driven (ultrafast) transmission electron microscopy. Our experiment achieved what is, in many respects, the most powerful
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20 Jul 2021 • Journal Article • Physical Review D
Experimental observation of acceleration-induced thermality
AbstractWe examine the radiation emitted by high-energy positrons channeled into silicon crystal samples. The positrons are modeled as semiclassical vector currents coupled to an Unruh-DeWitt detector to incorporate any local change in the energy of the positron. In the subsequent accelerated QED analysis, we discover a Larmor formula and power spectrum that are both thermalized
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20 Jul 2021 • Journal Article • Physical Review Research
Room-temperature coherent revival in an ensemble of quantum dots
Room-temperature coherent revival in an ensemble of quantum dotsSemiconductor quantum dots (QDs) are nanocrystals with atom-like delta function density of states and discrete energy levels. Advancements in fabrication led to record QD homogeneity and implementation in semiconductor laser structures which exhibit remarkable properties highlighted by ultra-narrow spectral emission and temperature-insensitive operation. An emerging application of such QDs is manipulation of optically induced coherent states of the QDs using ultra-short pulses. The most important of those is a demonstration of the hallmark quantum optics phenomena: collapse and revival of wave functions induced and observed in a QD ensemble in the form of an optical amplifier. The observation of quantum coherent revivals was not observed previously in solids, and in all media it was demonstrated only at cryogenic temperatures. Furthermore, coherently excited discrete homogeneous QD subgroups within an ensemble act as multiple quantum bits, resembling molecules in nuclear magnetic resonance (NMR) and can equally serve for quantum communication, simulation and sensing applications. The room temperature QDs exhibit a record long dephasing time (T2), we envision therefore a host of future compact quantum devices based on high quality QDs which do not require cryogenic cooling.
AbstractWe demonstrate the hallmark concept of periodic collapse and revival of coherence in a room-temperature ensemble of quantum dots (QDs) in the form of a 1.5-mm-long optical amplifier. Femtosecond excitation pulses induce coherent interactions with a number of