Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session A27: Driven and Dissipative AMO Systems ILive
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Sponsoring Units: DAMOP Chair: Nir Navon |
Monday, March 15, 2021 8:00AM - 8:12AM Live |
A27.00001: Dynamical Casimir effect in resonance fluorescence Lezhi Lo, Pak Tik Fong, Chi Kwong Law When a two-level atom interacts resonantly with a coherent electromagnetic field, the polarizability of the atom can be modulated due to the Rabi oscillations between atomic levels. We show that in the quantum vacuum, such a time-dependent atomic polarizability can lead to a resonant generation of photon pairs, a phenomenon reminiscent of photon emission in the dynamical Casimir effect (DCE). Specifically, we employ a dressing transformation to obtain an effective Hamiltonian which uncovers a polarizability-dependent parametric interaction corresponding to DCE. We determine the photon emission rate and indicate features of DCE photon pairs distinguishable from regular fluorescence photons. |
Monday, March 15, 2021 8:12AM - 8:24AM Live |
A27.00002: Exact quantum many-body scar states intrinsic to periodically driven system in the Rydberg-blockaded atom chain Sho Sugiura, Tomotaka kuwahara In a periodically driven many-body system, any quantum state usually ends up an infinite temperature state. This is called the Floquet energy eigenstate thermalization hypothesis (Floquet ETH). Here we discuss the violation of the Floquet ETH with realistic Hamiltonians. Our periodically driven model is based on the PXP type interaction, which is demonstrated in a recent experiment in the Rydberg atoms chain by Harvard group. By showing explicit expressions of the wave functions, we exactly prove the existence of the many-body scar states, which show non-thermal behavior, while other states obey the Floquet ETH. In addition, we systematically engineer various periodically-driven Hamiltonians having Floquet many-body scar states. |
Monday, March 15, 2021 8:24AM - 8:36AM Live |
A27.00003: Singularities in nearly-uniform 1D condensates due to $k^2$ loss Christopher Baldwin, Przemyslaw Bienias, Alexey V Gorshkov, Michael J. Gullans, Mohammad F. Maghrebi Certain dissipative systems have one-body loss proportional to $k^2$ ($k$ being momentum). One prominent example is Rydberg polaritons formed by electromagnetically-induced transparency, which have long been a leading candidate for studying the physics of interacting photons and hold promise as quantum information platforms. Here we show that one-dimensional condensates having such $k^2$ loss are unstable to long-wavelength density fluctuations in an unusual manner: after a prolonged period in which the condensate appears to relax to a uniform state, localized regions quickly dissipate and the depleted zones spread throughout the system. We connect this behavior to the leading-order equation for the nearly-uniform condensate, which develops singularities in finite time. Furthermore, the fronts which form can be described by novel dissipative solitons unrelated to the standard solitons in dissipation-free condensates. We close by discussing conditions under which such singularities and the resulting solitons can be observed experimentally. |
Monday, March 15, 2021 8:36AM - 8:48AM Live |
A27.00004: Stabilities and dynamics of a three-level extensions of the Dicke model Rui Lin, Francesco Ferri, Rodrigo Felipe Rosa-Medina Pimentel, Katrin Kroeger, Fabian Finger, Tobias Donner, Tilman Esslinger, Ramasubarian Chitra We consider an extension of the Dicke model which consists of a three-level system coupled to a cavity field. It can describe a Bose-Einstein-condensate coupled to an optical cavity and driven by a bichromatic laser pump. Although its closed-system phase diagram is rather typical to Dicke-type models, the introduction of cavity dissipation induces unusual stabilities and instabilities. For a wide range of parameters, the lowest-energy normal state becomes unstable towards a large collection of inverted states with higher energy, which indicates a finite density of states. This voluminous stability is connected to an emergent local U(1) symmetry in the system, and can be easily probed experimentally due to the sensitivity of final states of dynamical evolutions to the ramping protocols. |
Monday, March 15, 2021 8:48AM - 9:00AM Live |
A27.00005: The Bosonic RKKY Effect: Long-Range Order in a Spin-Boson Chain Matthew Butcher, Jed Pixley, Andriy Nevidomskyy Coupling of a two-level system to a dissipative bosonic bath is a well-studied problem known as the Caldeira-Leggett model. Here, we generalize this model to a 1D chain of Ising pseudospins coupled to a bosonic bath with Ohmic dissipation. Bath-induced interactions can produce a long-range ordered state even in the absence of direct interactions between the pseudospins. By analogy to the RKKY effect in metal-impurity systems, we refer to these induced interactions as the "Bosonic RKKY Effect". The long-range interactions depend on the form of the bath boson spectral function, which must be chosen based on the physical implementation. For a bath spectral function that decays exponentially above the cutoff frequency ωc, the bosonic RKKY interactions drive a quantum phase transition from a quantum paramagnet to a quantum Ising ferromagnet as the dissipation strength increases. By employing a quantum-to-classical mapping [1], we use classical Monte Carlo simulations to study the quantum phase diagram of the spin-boson chain. We find that the universality class of this quantum critical point is distinct from previously studied related models. |
Monday, March 15, 2021 9:00AM - 9:12AM Live |
A27.00006: Unraveling two-photon entanglement via the squeezing spectrum of light traveling through nanofiber-coupled atoms Jakob Hinney, Adarsh S. Prasad, Sahand Mahmoodian, Klemens Hammerer, Arno Rauschenbeutel, Philipp Schneeweiss, Jürgen Volz, Max Schemmer We observe that a weak guided light field transmitted through an ensemble of atoms coupled to an optical nanofiber exhibits quadrature squeezing. From the measured squeezing spectrum we gain direct access to the phase and amplitude of the energy-time entangled part of the two-photon wavefunction which arises from the strongly correlated transport of photons through the ensemble. For small atomic ensembles we observe a spectrum close to the lineshape of the atomic transition, while sidebands are observed for sufficiently large ensembles, in agreement with our theoretical predictions. Furthermore, we vary the detuning of the probe light with respect to the atomic resonance and infer the phase of the entangled two-photon wavefunction. From the amplitude and the phase of the spectrum, we reconstruct the real- and imaginary part of the time-domain wavefunction. Our characterization of the entangled two-photon component constitutes a diagnostic tool for quantum optics devices. |
Monday, March 15, 2021 9:12AM - 9:24AM Live |
A27.00007: Beating The House: Fast Simulation of Dissipative Quantum Systems with Ensemble Rank Truncation (ERT) Gerard McCaul, Kurt Aaron Jacobs, Denys Bondar We introduce a new technique for the simulation of dissipative quantum systems. This method is |
Monday, March 15, 2021 9:24AM - 9:36AM Live |
A27.00008: Liouvillian exceptional points and their relation to non-Hermitian Hamiltonians and quantum trajectories Fabrizio Minganti, Adam Miranowicz, Ravindra W. Chhajlany, Ievgen Arkhipov, Franco Nori Exceptional points (EPs) are spectral degeneracies of open systems that are attracting much interest in optics, plasmonics, and condensed matter physics. In the classical and semiclassical approaches, Hamiltonian EPs (HEPs) are degeneracies of non-Hermitian Hamiltonians such that at least two eigenfrequencies and the corresponding eigenstates coalesce. We argue that quantum jumps should be included in a fully quantum approach, e.g., that of the Lindblad master-equation approach. Thus, we define EPs via degeneracies of a Liouvillian superoperator (including quantum jumps, LEPs), and we clarify the relations between HEPs and LEPs [1]. The Liouvillian approach can be easily generalized to account for postselection of certain quantum jump trajectories [2]. The resulting hybrid-Liouvillian superoperator describes a new type of EPs, and can characterize experiments in the presence of finite-efficiency detectors[3]. |
Monday, March 15, 2021 9:36AM - 9:48AM Live |
A27.00009: Quantum Zeno transition in boundary-dissipative Ising model umar javed, Michael kolodrubetz The one-dimensional Ising model plays a defining role in many-body physics as one of few solvable models of quantum criticality. We study the one-dimensional Ising model in the presence of boundary dissipation. Numerically we find that in the presence of boundary dissipation boundary spin reaches a nonequilibrium steady state, which from naïve scaling arguments and RG calculation suggest that such dissipation is marginal. From our calculations of two-time correlation of the boundary spin, we find that the dynamics are singular near the Ising critical point, as well as showing new critical behavior at large dissipation. From TEBD calculations, we find these singularities to be robust to interactions. Analytically, our system can be mapped to a two-legged non-Hermitian model and we find that it has a singular edge spectrum with sharp transitions between 0, 1, and 2 edge states. |
Monday, March 15, 2021 9:48AM - 10:00AM Live |
A27.00010: Polaron effects on optical properties of Se+:Si spin-photon interfaces Leonard Ruocco, Mona Berciu Understanding the effects of vibrational modes on solid-state quantum bits proves a major challenge |
Monday, March 15, 2021 10:00AM - 10:12AM Live |
A27.00011: Noisy Coherent Population Trapping: Qubit Dark State Initialization in a Driven Λ system. Arshag Danageozian, Nathaniel Miller, Narayan Bhusal, Pratik Barge, Leigh M Norris, Lorenza Viola, Jonathan P Dowling Coherent Population Trapping (CPT) is a known quantum phenomenon in a driven Λ system with many applications. However, when a stochastic bath is present, the observed trapping is no longer perfect. We derive a time-convolutionless master equation describing the equilibration of the Λ system in the presence of additional temporally correlated noise, with an unknown decay parameter. Our simulations show a one-to-one correspondence between the decay parameter and the depth of the CPT dip in the photoluminescence spectrum, thereby enabling the unknown parameter to be estimated from the observed spectra. Finally, we apply our results to the problem of qubit state initialization in a Λ system via dark states and show how the stochastic bath affects the fidelity as a function of the desired dark state amplitudes. This means that dissipative state preparation becomes informed, and combined with a minimum fidelity requirement, certain dark states are eliminated from consideration. We show that an optimum choice of Rabi frequencies is possible. |
Monday, March 15, 2021 10:12AM - 10:24AM Live |
A27.00012: Diffusion coefficients of Lennard-Jones gases. Maxim Zyskin, Charles W. Monroe Molecular dynamics simulations of diffusion coefficients are based on modeling assumptions, such as diffusive regime, linear response, or Onsager regression hypothesis. In this talk, we compare our analytic results, our molecular dynamics simulations based on Green-Kubo or on Stefan-Maxwell-Onsager assumptions, and available experimental results, for relative diffusion coefficients of ideal Lennard-Jones gases. |
Monday, March 15, 2021 10:24AM - 10:36AM Live |
A27.00013: Classical-to-quantum transition of exceptional points induced by thermal noise Adam Miranowicz, Ravindra W. Chhajlany, Fabrizio Minganti, Ievgen Arkhipov, Franco Nori We study multiple effects of thermal noise on both the classical and quantum exceptional points in the experimental driven three-level system of Ref. [1]. In particular, we show that only in the absence of thermal noise the classical and quantum predictions are the same concerning exceptional points of non-Hermitian Hamiltonians and Liouvillians [2,3], respectively. Thus, thermal noise can induce a classical-to-quantum transition of exceptional points. This is a surprising result since thermal noise usually causes the opposite effect, i.e., a quantum-to-classical transition. |
Monday, March 15, 2021 10:36AM - 10:48AM Live |
A27.00014: Separation-dependent emission pathways of quantum emitters Jugal Talukdar, D. Blume System-environment interactions have been studied extensively for many decades and recent developments in quantum optics and circuit QED provide intriguing possibilities for realizing non-linear environments. The Bose-Hubbard lattice for photons, e.g., has been realized experimentally using superconducting circuits, thereby providing an exciting platform to study effective interactions between quantum emitters mediated by the engineered photonic environment. We consider a collection of macroscopically separated two-level emitters coupled to a non-linear environment and study the dissipative dynamics. Specifically, we report our theoretical progress on understanding the criteria for the existence of specific emission pathways as a function of the positions of the emitters. |
Monday, March 15, 2021 10:48AM - 11:00AM Not Participating |
A27.00015: Liouvillian exceptional points of any order in dissipative linear bosonic systems Ievgen Arkhipov, Adam Miranowicz, Fabrizio Minganti, Franco Nori In our study we explore exceptional points (EPs) of any higher order in dissipative linear bosonic systems based on the Liouvillian framework [1]. This framework, compared to the non-Hermitian Hamiltonians, can faithfully reveal the true quantum nature of EPs by taking into account quantum jumps. We show that the higher-order EPs of a Liouvillian can be identified by the coherence and spectral functions at the steady state. Moreover, the coherence functions can offer a convenient tool to probe extreme system sensitivity to external perturbations in the vicinity of such higher-order EPs [2]. |
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