1
|
Bond LJ, Safavi-Naini A, Minář J. Fast Quantum State Preparation and Bath Dynamics Using Non-Gaussian Variational Ansatz and Quantum Optimal Control. PHYSICAL REVIEW LETTERS 2024; 132:170401. [PMID: 38728702 DOI: 10.1103/physrevlett.132.170401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 01/15/2024] [Accepted: 03/25/2024] [Indexed: 05/12/2024]
Abstract
Fast preparation of quantum many-body states is essential for myriad quantum algorithms and metrological applications. Here, we develop a new pathway for fast, nonadiabatic preparation of quantum many-body states that combines quantum optimal control with a variational Ansatz based on non-Gaussian states. We demonstrate our approach on the spin-boson model, a single spin interacting with the bath. We use a multipolaron Ansatz to prepare near-critical ground states. For one mode, we achieve a reduction in infidelity of up to ≈60 (≈10) times compared to linear (optimized local adiabatic) ramps; for many modes, we achieve a reduction in infidelity of up to ≈5 times compared to nonadiabatic linear ramps. Further, we show that the typical control quantity, the leakage from the variational manifold, provides only a loose bound on the state's fidelity. Instead, in analogy to the bond dimension of matrix product states, we suggest a controlled convergence criterion based on the number of polarons. Finally, motivated by the possibility of realizations in trapped ions, we study the dynamics of a system with bath properties going beyond the paradigm of (sub- and/or super-) Ohmic couplings.
Collapse
Affiliation(s)
- Liam J Bond
- Institute for Theoretical Physics, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
- QuSoft, Science Park 123, 1098 XG Amsterdam, The Netherlands
| | - Arghavan Safavi-Naini
- Institute for Theoretical Physics, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
- QuSoft, Science Park 123, 1098 XG Amsterdam, The Netherlands
| | - Jiří Minář
- Institute for Theoretical Physics, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
- QuSoft, Science Park 123, 1098 XG Amsterdam, The Netherlands
- CWI, Science Park 904, 1098 XH Amsterdam, The Netherlands
| |
Collapse
|
2
|
Belyansky R, Whitsitt S, Mueller N, Fahimniya A, Bennewitz ER, Davoudi Z, Gorshkov AV. High-Energy Collision of Quarks and Mesons in the Schwinger Model: From Tensor Networks to Circuit QED. PHYSICAL REVIEW LETTERS 2024; 132:091903. [PMID: 38489632 DOI: 10.1103/physrevlett.132.091903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 12/23/2023] [Accepted: 01/23/2024] [Indexed: 03/17/2024]
Abstract
With the aim of studying nonperturbative out-of-equilibrium dynamics of high-energy particle collisions on quantum simulators, we investigate the scattering dynamics of lattice quantum electrodynamics in 1+1 dimensions. Working in the bosonized formulation of the model and in the thermodynamic limit, we use uniform-matrix-product-state tensor networks to construct multiparticle wave-packet states, evolve them in time, and detect outgoing particles post collision. This facilitates the numerical simulation of scattering experiments in both confined and deconfined regimes of the model at different energies, giving rise to rich phenomenology, including inelastic production of quark and meson states, meson disintegration, and dynamical string formation and breaking. We obtain elastic and inelastic scattering cross sections, together with time-resolved momentum and position distributions of the outgoing particles. Furthermore, we propose an analog circuit-QED implementation of the scattering process that is native to the platform, requires minimal ingredients and approximations, and enables practical schemes for particle wave-packet preparation and evolution. This study highlights the role of classical and quantum simulation in enhancing our understanding of scattering processes in quantum field theories in real time.
Collapse
Affiliation(s)
- Ron Belyansky
- Joint Center for Quantum Information and Computer Science, NIST/University of Maryland, College Park, Maryland 20742 USA
- Joint Quantum Institute, NIST/University of Maryland, College Park, Maryland 20742 USA
| | - Seth Whitsitt
- Joint Center for Quantum Information and Computer Science, NIST/University of Maryland, College Park, Maryland 20742 USA
- Joint Quantum Institute, NIST/University of Maryland, College Park, Maryland 20742 USA
| | - Niklas Mueller
- InQubator for Quantum Simulation (IQuS), Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | - Ali Fahimniya
- Joint Center for Quantum Information and Computer Science, NIST/University of Maryland, College Park, Maryland 20742 USA
- Joint Quantum Institute, NIST/University of Maryland, College Park, Maryland 20742 USA
| | - Elizabeth R Bennewitz
- Joint Center for Quantum Information and Computer Science, NIST/University of Maryland, College Park, Maryland 20742 USA
- Joint Quantum Institute, NIST/University of Maryland, College Park, Maryland 20742 USA
| | - Zohreh Davoudi
- Joint Center for Quantum Information and Computer Science, NIST/University of Maryland, College Park, Maryland 20742 USA
- Maryland Center for Fundamental Physics and Department of Physics, University of Maryland, College Park, Maryland 20742 USA
| | - Alexey V Gorshkov
- Joint Center for Quantum Information and Computer Science, NIST/University of Maryland, College Park, Maryland 20742 USA
- Joint Quantum Institute, NIST/University of Maryland, College Park, Maryland 20742 USA
| |
Collapse
|
3
|
Amati G, Mannouch JR, Richardson JO. Detailed balance in mixed quantum-classical mapping approaches. J Chem Phys 2023; 159:214114. [PMID: 38054513 DOI: 10.1063/5.0176291] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 11/07/2023] [Indexed: 12/07/2023] Open
Abstract
The violation of detailed balance poses a serious problem for the majority of current quasiclassical methods for simulating nonadiabatic dynamics. In order to analyze the severity of the problem, we predict the long-time limits of the electronic populations according to various quasiclassical mapping approaches by applying arguments from classical ergodic theory. Our analysis confirms that regions of the mapping space that correspond to negative populations, which most mapping approaches introduce in order to go beyond the Ehrenfest approximation, pose the most serious issue for reproducing the correct thermalization behavior. This is because inverted potentials, which arise from negative electronic populations entering the nuclear force, can result in trajectories unphysically accelerating off to infinity. The recently developed mapping approach to surface hopping (MASH) provides a simple way of avoiding inverted potentials while retaining an accurate description of the dynamics. We prove that MASH, unlike any other quasiclassical approach, is guaranteed to describe the exact thermalization behavior of all quantum-classical systems, confirming it as one of the most promising methods for simulating nonadiabatic dynamics in real condensed-phase systems.
Collapse
Affiliation(s)
- Graziano Amati
- Department of Chemistry and Applied Biosciences, ETH Zürich, 8093 Zürich, Switzerland
| | - Jonathan R Mannouch
- Department of Chemistry and Applied Biosciences, ETH Zürich, 8093 Zürich, Switzerland
| | - Jeremy O Richardson
- Department of Chemistry and Applied Biosciences, ETH Zürich, 8093 Zürich, Switzerland
| |
Collapse
|
4
|
Yadav PK, Upadhyay R, Kumar R, Nukala P, Upadhyay C. Emergence of field-induced memory effect in spin ices. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:495601. [PMID: 37586379 DOI: 10.1088/1361-648x/acf106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 08/16/2023] [Indexed: 08/18/2023]
Abstract
Out-of-equilibrium investigation of strongly correlated materials deciphers the hidden equilibrium properties. Herein, we have investigated the out-of-equilibrium magnetic properties of polycrystalline Dy2Ti2O7and Ho2Ti2O7spin ices. Our experimental findings reveal the emergence of magnetic field-induced anomalous hysteresis observed solely in temperature-and magnetic field-dependent AC susceptibility measurements. The observed memory effect (anomalous thermomagnetic hysteresis) exhibits a strong dependence on both thermal and non-thermal driving variables. Owing to the non-collinear spin structure, the applied DC bias magnetic field produces quenched disorder sites in the cooperative Ising spin matrix and suppresses the spin-phonon coupling. These quench disorders create a dynamic spin correlation, having slow spin relaxation and quick decay time, which additionally contribute to AC susceptibility. The initial conditions and measurement protocol decide the magnitude and sign of this dynamical term contributing to AC susceptibility. It is being suggested that such out-of-equilibrium properties arise from the combined influences of geometric frustration, disorder, and the cooperative nature of spin dynamics exhibited by these materials.
Collapse
Affiliation(s)
- Pramod K Yadav
- Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012, India
| | - Rajnikant Upadhyay
- School of Materials Science and Technology, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, India
| | - Rahul Kumar
- School of Advanced Materials and Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
| | - Pavan Nukala
- Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012, India
| | - Chandan Upadhyay
- School of Materials Science and Technology, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, India
| |
Collapse
|
5
|
Choi JR. Dynamics of Dispersive Measurements of Flux-Qubit States: Energy-Level Splitting Connected to Quantum Wave Mechanics. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2395. [PMID: 37686903 PMCID: PMC10490274 DOI: 10.3390/nano13172395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 08/09/2023] [Accepted: 08/16/2023] [Indexed: 09/10/2023]
Abstract
Superconducting flux qubits have many advantages as a storage of quantum information, such as broad range tunability of frequency, small-size fabricability, and high controllability. In the flux qubit-oscillator, qubits are connected to SQUID resonators for the purpose of performing dispersive non-destructive readouts of qubit signals with high fidelity. In this work, we propose a theoretical model for analyzing quantum characteristics of a flux qubit-oscillator on the basis of quantum solutions obtained using a unitary transformation approach. The energy levels of the combined system (qubit + resonator) are analyzed in detail. Equally spaced each energy level of the resonator splits into two parts depending on qubit states. Besides, coupling of the qubit to the resonator brings about an additional modification in the split energy levels. So long as the coupling strength and the tunnel splitting are not zero but finite values, the energy-level splitting of the resonator does not disappear. We conclude that quantum nondemolition dispersive measurements of the qubit states are possible by inducing bifurcation of the resonator states through the coupling.
Collapse
Affiliation(s)
- Jeong Ryeol Choi
- School of Electronic Engineering, Kyonggi University, Yeongtong-gu, Suwon 16227, Gyeonggi-do, Republic of Korea
| |
Collapse
|
6
|
Amati G, Runeson JE, Richardson JO. On detailed balance in nonadiabatic dynamics: From spin spheres to equilibrium ellipsoids. J Chem Phys 2023; 158:064113. [PMID: 36792511 DOI: 10.1063/5.0137828] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Trajectory-based methods that propagate classical nuclei on multiple quantum electronic states are often used to simulate nonadiabatic processes in the condensed phase. A long-standing problem of these methods is their lack of detailed balance, meaning that they do not conserve the equilibrium distribution. In this article, we investigate ideas for restoring detailed balance in mixed quantum-classical systems by tailoring the previously proposed spin-mapping approach to thermal equilibrium. We find that adapting the spin magnitude can recover the correct long-time populations but is insufficient to conserve the full equilibrium distribution. The latter can however be achieved by a more flexible mapping of the spin onto an ellipsoid, which is constructed to fulfill detailed balance for arbitrary potentials. This ellipsoid approach solves the problem of negative populations that has plagued previous mapping approaches and can therefore be applied also to strongly asymmetric and anharmonic systems. Because it conserves the thermal distribution, the method can also exploit efficient sampling schemes used in standard molecular dynamics, which drastically reduces the number of trajectories needed for convergence. The dynamics does however still have mean-field character, as is observed most clearly by evaluating reaction rates in the golden-rule limit. This implies that although the ellipsoid mapping provides a rigorous framework, further work is required to find an accurate classical-trajectory approximation that captures more properties of the true quantum dynamics.
Collapse
Affiliation(s)
- Graziano Amati
- Laboratory of Physical Chemistry, ETH Zürich, 8093 Zürich, Switzerland
| | - Johan E Runeson
- Laboratory of Physical Chemistry, ETH Zürich, 8093 Zürich, Switzerland
| | | |
Collapse
|
7
|
Arrachea L. Energy dynamics, heat production and heat-work conversion with qubits: toward the development of quantum machines. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2023; 86:036501. [PMID: 36603220 DOI: 10.1088/1361-6633/acb06b] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 01/05/2023] [Indexed: 06/17/2023]
Abstract
We present an overview of recent advances in the study of energy dynamics and mechanisms for energy conversion in qubit systems with special focus on realizations in superconducting quantum circuits. We briefly introduce the relevant theoretical framework to analyze heat generation, energy transport and energy conversion in these systems with and without time-dependent driving considering the effect of equilibrium and non-equilibrium environments. We analyze specific problems and mechanisms under current investigation in the context of qubit systems. These include the problem of energy dissipation and possible routes for its control, energy pumping between driving sources and heat pumping between reservoirs, implementation of thermal machines and mechanisms for energy storage. We highlight the underlying fundamental phenomena related to geometrical and topological properties, as well as many-body correlations. We also present an overview of recent experimental activity in this field.
Collapse
Affiliation(s)
- Liliana Arrachea
- Escuela de Ciencia y Tecnología and ICIFI, Universidad de San Martín, Av. 25 de Mayo y Francia, 1650 Buenos Aires, Argentina
| |
Collapse
|
8
|
Grimaudo R, Valenti D, Sergi A, Messina A. Superradiant Quantum Phase Transition for an Exactly Solvable Two-Qubit Spin-Boson Model. ENTROPY (BASEL, SWITZERLAND) 2023; 25:e25020187. [PMID: 36832554 PMCID: PMC9956034 DOI: 10.3390/e25020187] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 01/12/2023] [Accepted: 01/16/2023] [Indexed: 06/01/2023]
Abstract
A spin-boson-like model with two interacting qubits is analysed. The model turns out to be exactly solvable since it is characterized by the exchange symmetry between the two spins. The explicit expressions of eigenstates and eigenenergies make it possible to analytically unveil the occurrence of first-order quantum phase transitions. The latter are physically relevant since they are characterized by abrupt changes in the two-spin subsystem concurrence, in the net spin magnetization and in the mean photon number.
Collapse
Affiliation(s)
- Roberto Grimaudo
- Dipartimento di Fisica e Chimica “Emilio Segrè”, Group of Interdisciplinary Theoretical Physics, Università degli Studi di Palermo, Viale delle Scienze Ed. 18, 90128 Palermo, Italy
| | - Davide Valenti
- Dipartimento di Fisica e Chimica “Emilio Segrè”, Group of Interdisciplinary Theoretical Physics, Università degli Studi di Palermo, Viale delle Scienze Ed. 18, 90128 Palermo, Italy
| | - Alessandro Sergi
- Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra, Università degli Studi di Messina, Viale F. Stagno d’Alcontres 31, 98166 Messina, Italy
- Institute of Systems Science, Durban University of Technology, P.O. Box 1334, Durban 4000, South Africa
| | - Antonino Messina
- Dipartimento di Matematica ed Informatica, Università degli Studi di Palermo, Via Archirafi 34, 90123 Palermo, Italy
| |
Collapse
|
9
|
Kaur K, Sépulcre T, Roch N, Snyman I, Florens S, Bera S. Spin-Boson Quantum Phase Transition in Multilevel Superconducting Qubits. PHYSICAL REVIEW LETTERS 2021; 127:237702. [PMID: 34936769 DOI: 10.1103/physrevlett.127.237702] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 09/21/2021] [Accepted: 11/08/2021] [Indexed: 06/14/2023]
Abstract
Superconducting circuits are currently developed as a versatile platform for the exploration of many-body physics, by building on nonlinear elements that are often idealized as two-level qubits. A classic example is given by a charge qubit that is capacitively coupled to a transmission line, which leads to the celebrated spin-boson description of quantum dissipation. We show that the intrinsic multilevel structure of superconducting qubits drastically restricts the validity of the spin-boson paradigm due to phase localization, which spreads the wave function over many charge states. Numerical renormalization group simulations also show that the quantum critical point moves out of the physically accessible range in the multilevel regime. Imposing charge discreteness in a simple variational state accounts for these multilevel effects, which are relevant for a large class of devices.
Collapse
Affiliation(s)
- Kuljeet Kaur
- Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Théo Sépulcre
- Univ. Grenoble Alpes, CNRS, Institut Néel, F-38000 Grenoble, France
| | - Nicolas Roch
- Univ. Grenoble Alpes, CNRS, Institut Néel, F-38000 Grenoble, France
| | - Izak Snyman
- Mandelstam Institute for Theoretical Physics, School of Physics, University of the Witwatersrand, Johannesburg, South Africa
| | - Serge Florens
- Univ. Grenoble Alpes, CNRS, Institut Néel, F-38000 Grenoble, France
| | - Soumya Bera
- Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076, India
| |
Collapse
|
10
|
Funo K, Lambert N, Nori F. General Bound on the Performance of Counter-Diabatic Driving Acting on Dissipative Spin Systems. PHYSICAL REVIEW LETTERS 2021; 127:150401. [PMID: 34678023 DOI: 10.1103/physrevlett.127.150401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 09/15/2021] [Indexed: 06/13/2023]
Abstract
Counter-diabatic driving (CD) is a technique in quantum control theory designed to counteract nonadiabatic excitations and guide the system to follow its instantaneous energy eigenstates, and hence has applications in state preparation, quantum annealing, and quantum thermodynamics. However, in many practical situations, the effect of the environment cannot be neglected, and the performance of the CD is expected to degrade. To arrive at general bounds on the resulting error of CD in this situation we consider a driven spin-boson model as a prototypical setup. The inequalities we obtain, in terms of either the Bures angle or the fidelity, allow us to estimate the maximum error solely characterized by the parameters of the system and the bath. By utilizing the analytical form of the upper bound, we demonstrate that the error can be systematically reduced through optimization of the external driving protocol of the system. We also show that if we allow a time-dependent system-bath coupling angle, the obtained bound can be saturated and realizes unit fidelity.
Collapse
Affiliation(s)
- Ken Funo
- Theoretical Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama 351-0198, Japan
| | - Neill Lambert
- Theoretical Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama 351-0198, Japan
| | - Franco Nori
- Theoretical Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama 351-0198, Japan
- RIKEN Center for Quantum Computing (RQC), Wako-shi, Saitama 351-0198, Japan
- Physics Department, The University of Michigan, Ann Arbor, Michigan 48109-1040, USA
| |
Collapse
|
11
|
Dolgitzer D, Zeng D, Chen Y. Dynamical quantum phase transitions in the spin-boson model. OPTICS EXPRESS 2021; 29:23988-23996. [PMID: 34614652 DOI: 10.1364/oe.434183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 07/05/2021] [Indexed: 06/13/2023]
Abstract
We study dynamical quantum phase transitions in a 2-qubit system interacting with a transverse field and a quantized bosonic environment in the context of open quantum systems. By applying the stochastic Schrödinger equation approach, the model with a spin-boson type of coupling can be solved numerically. It is observed that the dynamics of the rate function of the Loschmidt echo in a 2-qubit system within a finite size of Hilbert space exhibit nonanalyticity when the direction of the transverse field coupled to the system is under a sudden quench. Moreover, we demonstrate that the memory time of the environment and the coupling strength between the system and the transverse field can jointly impact the dynamics of the rate function. We also supply a semi-classical explanation to bridge the dynamical quantum phase transitions in many-body systems and the non-Markovian dynamics of open quantum systems.
Collapse
|
12
|
Shapiro DS. Transport of pseudothermal photons through an anharmonic cavity. Sci Rep 2021; 11:8328. [PMID: 33859246 PMCID: PMC8050331 DOI: 10.1038/s41598-021-87536-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Accepted: 03/31/2021] [Indexed: 11/14/2022] Open
Abstract
Under nonequilibrium conditions, quantum optical systems reveal unusual properties that might be distinct from those in condensed matter. The fundamental reason is that photonic eigenstates can have arbitrary occupation numbers, whereas in electronic systems these are limited by the Pauli principle. Here, we address the steady-state transport of pseudothermal photons between two waveguides connected through a cavity with Bose–Hubbard interaction between photons. One of the waveguides is subjected to a broadband incoherent pumping. We predict a continuous transition between the regimes of Lorentzian and Gaussian chaotic light emitted by the cavity. The rich variety of nonequilibrium transport regimes is revealed by the zero-frequency noise. There are three limiting cases, in which the noise-current relation is characterized by a power-law, \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$S\propto J^\gamma$$\end{document}S∝Jγ. The Lorentzian light corresponds to Breit-Wigner-like transmission and \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\gamma =2$$\end{document}γ=2. The Gaussian regime corresponds to many-body transport with the shot noise (\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\gamma =1$$\end{document}γ=1) at large currents; at low currents, however, we find an unconventional exponent \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\gamma =3/2$$\end{document}γ=3/2 indicating a nontrivial interplay between multi-photon transitions and incoherent pumping. The nonperturbative solution for photon dephasing is obtained in the framework of the Keldysh field theory and Caldeira-Leggett effective action. These findings might be relevant for experiments on photon blockade in superconducting qubits, thermal states transfer, and photon statistics probing.
Collapse
Affiliation(s)
- Dmitriy S Shapiro
- Dukhov Research Institute of Automatics (VNIIA), Moscow, Russia, 127055. .,Department of Physics, National Research University Higher School of Economics, Moscow, Russia, 101000. .,Laboratory of Superconducting Metamaterials, National University of Science and Technology MISiS, Moscow, Russia, 119049. .,V. A. Kotel'nikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Moscow, Russia, 125009.
| |
Collapse
|
13
|
Burshtein A, Kuzmin R, Manucharyan VE, Goldstein M. Photon-Instanton Collider Implemented by a Superconducting Circuit. PHYSICAL REVIEW LETTERS 2021; 126:137701. [PMID: 33861127 DOI: 10.1103/physrevlett.126.137701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 03/02/2021] [Indexed: 06/12/2023]
Abstract
Instantons, spacetime-localized quantum field tunneling events, are ubiquitous in correlated condensed matter and high-energy systems. However, their direct observation through collisions with conventional particles has not been considered possible. We show how recent advances in circuit quantum electrodynamics, specifically, the realization of galvanic coupling of a transmon qubit to a high-impedance transmission line, allows the observation of inelastic collisions of single microwave photons with instantons (phase slips). We develop a formalism for calculating the photon-instanton cross section, which should be useful in other quantum field theoretical contexts. In particular, we show that the inelastic scattering probability can significantly exceed the effect of conventional Josephson quartic anharmonicity and reach order-unity values.
Collapse
Affiliation(s)
- Amir Burshtein
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Roman Kuzmin
- Department of Physics, University of Maryland, College Park, Maryland 20742, USA
| | | | - Moshe Goldstein
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 6997801, Israel
| |
Collapse
|
14
|
Engelhardt G, Cao J. Dynamical Symmetries and Symmetry-Protected Selection Rules in Periodically Driven Quantum Systems. PHYSICAL REVIEW LETTERS 2021; 126:090601. [PMID: 33750178 DOI: 10.1103/physrevlett.126.090601] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 12/07/2020] [Accepted: 02/09/2021] [Indexed: 06/12/2023]
Abstract
In recent experiments, the light-matter interaction has reached the ultrastrong coupling limit, which can give rise to dynamical generalizations of spatial symmetries in periodically driven systems. Here, we present a unified framework of dynamical-symmetry-protected selection rules based on Floquet response theory. Within this framework, we study rotational, parity, particle-hole, chiral, and time-reversal symmetries and the resulting selection rules in spectroscopy, including symmetry-protected dark states (spDS), symmetry-protected dark bands, and symmetry-induced transparency. Specifically, dynamical rotational and parity symmetries establish spDS and symmetry-protected dark band conditions. A particle-hole symmetry introduces spDSs for symmetry-related Floquet states and also a symmetry-induced transparency at quasienergy crossings. Chiral symmetry and time-reversal symmetry alone do not imply spDS conditions but can be combined to define a particle-hole symmetry. These symmetry conditions arise from destructive interference due to the synchronization of symmetric quantum systems with the periodic driving. Our predictions reveal new physical phenomena when a quantum system reaches the strong light-matter coupling regime, which is important for superconducting qubits, atoms and molecules in optical or plasmonic field cavities, and optomechanical systems.
Collapse
Affiliation(s)
- Georg Engelhardt
- Beijing Computational Science Research Center, Beijing 100193, People's Republic of China
| | - Jianshu Cao
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| |
Collapse
|
15
|
Wen PY, Lin KT, Kockum AF, Suri B, Ian H, Chen JC, Mao SY, Chiu CC, Delsing P, Nori F, Lin GD, Hoi IC. Large Collective Lamb Shift of Two Distant Superconducting Artificial Atoms. PHYSICAL REVIEW LETTERS 2019; 123:233602. [PMID: 31868475 DOI: 10.1103/physrevlett.123.233602] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Indexed: 06/10/2023]
Abstract
Virtual photons can mediate interaction between atoms, resulting in an energy shift known as a collective Lamb shift. Observing the collective Lamb shift is challenging, since it can be obscured by radiative decay and direct atom-atom interactions. Here, we place two superconducting qubits in a transmission line terminated by a mirror, which suppresses decay. We measure a collective Lamb shift reaching 0.8% of the qubit transition frequency and twice the transition linewidth. We also show that the qubits can interact via the transmission line even if one of them does not decay into it.
Collapse
Affiliation(s)
- P Y Wen
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Center for Quantum Technology, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - K-T Lin
- CQSE, Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - A F Kockum
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
- Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama 351-0198, Japan
| | - B Suri
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
- Department of Instrumentation and Applied Physics, Indian Institute of Science, Bengaluru 560012, India
| | - H Ian
- Institute of Applied Physics and Materials Engineering, University of Macau, Macau, China
- UMacau Zhuhai Research Institute, Zhuhai, Guangdong 519031, China
| | - J C Chen
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Center for Quantum Technology, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - S Y Mao
- Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 30013, Taiwan
| | - C C Chiu
- Department of Electrical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - P Delsing
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - F Nori
- Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama 351-0198, Japan
- Physics Department, The University of Michigan, Ann Arbor, Michigan 48109-1040, USA
| | - G-D Lin
- CQSE, Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - I-C Hoi
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Center for Quantum Technology, National Tsing Hua University, Hsinchu 30013, Taiwan
| |
Collapse
|
16
|
Observation of quantum many-body effects due to zero point fluctuations in superconducting circuits. Nat Commun 2019; 10:5259. [PMID: 31748501 PMCID: PMC6868017 DOI: 10.1038/s41467-019-13199-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 10/15/2019] [Indexed: 11/16/2022] Open
Abstract
Electromagnetic fields possess zero point fluctuations which lead to observable effects such as the Lamb shift and the Casimir effect. In the traditional quantum optics domain, these corrections remain perturbative due to the smallness of the fine structure constant. To provide a direct observation of non-perturbative effects driven by zero point fluctuations in an open quantum system we wire a highly non-linear Josephson junction to a high impedance transmission line, allowing large phase fluctuations across the junction. Consequently, the resonance of the former acquires a relative frequency shift that is orders of magnitude larger than for natural atoms. Detailed modeling confirms that this renormalization is non-linear and quantum. Remarkably, the junction transfers its non-linearity to about thirty environmental modes, a striking back-action effect that transcends the standard Caldeira-Leggett paradigm. This work opens many exciting prospects for longstanding quests such as the tailoring of many-body Hamiltonians in the strongly non-linear regime, the observation of Bloch oscillations, or the development of high-impedance qubits. Advances in the design and fabrication of superconducting devices enable physicists to design and monitor quantum electronic systems in synthetic environments. Here the authors observe how many-body effects influence the zero-point motion of a Josephson junction coupled to a high impedance transmission line.
Collapse
|
17
|
Engelhardt G, Platero G, Cao J. Discontinuities in Driven Spin-Boson Systems due to Coherent Destruction of Tunneling: Breakdown of the Floquet-Gibbs Distribution. PHYSICAL REVIEW LETTERS 2019; 123:120602. [PMID: 31633942 DOI: 10.1103/physrevlett.123.120602] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Indexed: 06/10/2023]
Abstract
If an open quantum system is periodically driven with high frequency and the driving commutes with the system-bath coupling operator, it is known that the system approaches a Floquet-Gibbs state, a generalization of Gibbs states to periodically driven systems. Here, we investigate the stationary state of an ac-driven system when the driving and dissipation are noncommutative. Then, the resulting stationary state does not obey the Floquet-Gibbs distribution, and the system dynamics is determined by inelastic scattering processes of the driving field. Based on the Floquet-Redfield formalism, we show that the probability distribution can exhibit population inversion and discontinuities, i.e., jumps, for parameters at which coherent destruction of tunneling takes place. These discontinuities can be observed as intensity jumps in the emission into the bath.
Collapse
Affiliation(s)
- Georg Engelhardt
- Beijing Computational Science Research Center, Beijing 100193, People's Republic of China
| | - Gloria Platero
- Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Spain
| | - Jianshu Cao
- Beijing Computational Science Research Center, Beijing 100193, People's Republic of China
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| |
Collapse
|
18
|
Lambert N, Ahmed S, Cirio M, Nori F. Modelling the ultra-strongly coupled spin-boson model with unphysical modes. Nat Commun 2019; 10:3721. [PMID: 31427583 PMCID: PMC6700178 DOI: 10.1038/s41467-019-11656-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 07/29/2019] [Indexed: 11/23/2022] Open
Abstract
A quantum system weakly coupled to a zero-temperature environment will relax, via spontaneous emission, to its ground-state. However, when the coupling to the environment is ultra-strong the ground-state is expected to become dressed with virtual excitations. This regime is difficult to capture with some traditional methods because of the explosion in the number of Matsubara frequencies, i.e., exponential terms in the free-bath correlation function. To access this regime we generalize both the hierarchical equations of motion and pseudomode methods, taking into account this explosion using only a biexponential fitting function. We compare these methods to the reaction coordinate mapping, which helps show how these sometimes neglected Matsubara terms are important to regulate detailed balance and prevent the unphysical emission of virtual excitations. For the pseudomode method, we present a general proof of validity for the use of superficially unphysical Matsubara-modes, which mirror the mathematical essence of the Matsubara frequencies.
Collapse
Affiliation(s)
- Neill Lambert
- Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama, 351-0198, Japan.
| | - Shahnawaz Ahmed
- Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama, 351-0198, Japan
- Wallenberg Centre for Quantum Technology, Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Mauro Cirio
- Graduate School of China Academy of Engineering Physics, Haidian District, Beijing, 100193, China.
| | - Franco Nori
- Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama, 351-0198, Japan
- Department of Physics, University of Michigan, Ann Arbor, MI, 48109-1040, USA
| |
Collapse
|
19
|
Magazzù L, Denisov S, Hänggi P. Asymptotic Floquet states of a periodically driven spin-boson system in the nonperturbative coupling regime. Phys Rev E 2018; 98:022111. [PMID: 30253481 DOI: 10.1103/physreve.98.022111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Indexed: 06/08/2023]
Abstract
Being an exemplary model of open quantum system, the spin-boson model is widely employed in theoretical and experimental studies. Beyond the weak coupling limit, the spin-boson dynamics can be described by a time-nonlocal generalized master equation with a memory kernel accounting for the dissipative effects induced by the bosonic environment. When the spin is in addition modulated by an external time-periodic electromagnetic field, the interplay between dissipation and forcing provides a spectrum of nontrivial asymptotic states, especially so in the regime of nonlinear response. Here we implement the method for evaluating the dissipative Floquet dynamics of non-Markovian systems introduced in Magazzù et al. [Phys. Rev. A 96, 042103 (2017)2469-992610.1103/PhysRevA.96.042103] to obtain these nonequilibrium asymptotic states.
Collapse
Affiliation(s)
- Luca Magazzù
- Institute of Physics, University of Augsburg, Universitätsstrasse 1, D-86135 Augsburg, Germany
| | - Sergey Denisov
- Institute of Physics, University of Augsburg, Universitätsstrasse 1, D-86135 Augsburg, Germany
- Department of Applied Mathematics, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod 603950, Russia
- Sumy State University, Rimsky-Korsakov Street 2, 40007 Sumy, Ukraine
| | - Peter Hänggi
- Institute of Physics, University of Augsburg, Universitätsstrasse 1, D-86135 Augsburg, Germany
- Nanosystems Initiative Munich, Schellingstraße 4, D-80799 München, Germany
| |
Collapse
|