Measuring Loschmidt echo via Floquet engineering in superconducting circuits

2021 ◽  
Author(s):  
S. K. Zhao ◽  
Zi-Yong Ge ◽  
Zhongcheng Xiang ◽  
G. M. Xue ◽  
H. S. Yan ◽  
...  
Keyword(s):  
Time Reversal ◽  
Bell State ◽  
Quantum Evolution ◽  
Many Body ◽  
Small Perturbations ◽  
Main Challenge ◽  
State Recovery ◽  
Qubit System ◽  
State Evolution ◽  
Loschmidt Echo

Abstract The Loschmidt echo is a useful diagnostic for the perfection of quantum time-reversal process and the sensitivity of quantum evolution to small perturbations. The main challenge for measuring the Loschmidt echo is the time reversal of a quantum evolution. In this work, we demonstrate the measurement of the Loschmidt echo in a superconducting 10-qubit system using Floquet engineering and discuss the imperfection of an initial Bell-state recovery arising from the next-nearest-neighbour (NNN) coupling present in the qubit device. Our results show that the Loschmidt echo is very sensitive to small perturbations during quantum-state evolution, in contrast to the quantities like qubit population that is often considered in the time-reversal experiment. These properties may be employed for the investigation of multiqubit system concerning many-body decoherence and entanglement, etc., especially when devices with reduced or vanishing NNN coupling are used.

scholarly journals Loschmidt echo and time reversal in complex systems

2016 ◽  
Vol 374 (2069) ◽  
pp. 20150383 ◽  
Author(s):  
Arseni Goussev ◽  
Rodolfo A. Jalabert ◽  
Horacio M. Pastawski ◽  
Diego A. Wisniacki
Keyword(s):  
Complex Systems ◽  
Time Reversal ◽  
Cold Atoms ◽  
Quantum Evolution ◽  
Many Body ◽  
The Past ◽  
Reversal Procedure ◽  
Physical Effects ◽  
Loschmidt Echo ◽  
The Stability

Echoes are ubiquitous phenomena in several branches of physics, ranging from acoustics, optics, condensed matter and cold atoms to geophysics. They are at the base of a number of very useful experimental techniques, such as nuclear magnetic resonance, photon echo and time-reversal mirrors. Particularly interesting physical effects are obtained when the echo studies are performed on complex systems, either classically chaotic, disordered or many-body. Consequently, the term Loschmidt echo has been coined to designate and quantify the revival occurring when an imperfect time-reversal procedure is applied to a complex quantum system, or equivalently to characterize the stability of quantum evolution in the presence of perturbations. Here, we present the articles which discuss the work that has shaped the field in the past few years.

scholarly journals Probing Many-Body Systems Near Spectral Degeneracies

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1796
Author(s):  
Klaus Ziegler
Keyword(s):  
Decay Rate ◽  
Correlation Matrix ◽  
Time Correlation ◽  
General Concept ◽  
Quantum Systems ◽  
Quantum Evolution ◽  
Many Body ◽  
Space Localization ◽  
Many Body Systems ◽  
Random Times

The diagonal elements of the time correlation matrix are used to probe closed quantum systems that are measured at random times. This enables us to extract two distinct parts of the quantum evolution, a recurrent part and an exponentially decaying part. This separation is strongly affected when spectral degeneracies occur, for instance, in the presence of spontaneous symmetry breaking. Moreover, the slowest decay rate is determined by the smallest energy level spacing, and this decay rate diverges at the spectral degeneracies. Probing the quantum evolution with the diagonal elements of the time correlation matrix is discussed as a general concept and tested in the case of a bosonic Josephson junction. It reveals for the latter characteristic properties at the transition to Hilbert-space localization.

scholarly journals Interaction instability of localization in quasiperiodic systems

2018 ◽  
Vol 115 (18) ◽  
pp. 4595-4600 ◽  
Author(s):  
Marko Žnidarič ◽  
Marko Ljubotina
Keyword(s):  
Transport Properties ◽  
Quantum Systems ◽  
Theoretical Physics ◽  
Solvable Models ◽  
Many Body ◽  
Small Perturbations ◽  
One Dimensional ◽  
Quasiperiodic Potential ◽  
Quasiperiodic Systems ◽  
Small Interactions

Integrable models form pillars of theoretical physics because they allow for full analytical understanding. Despite being rare, many realistic systems can be described by models that are close to integrable. Therefore, an important question is how small perturbations influence the behavior of solvable models. This is particularly true for many-body interacting quantum systems where no general theorems about their stability are known. Here, we show that no such theorem can exist by providing an explicit example of a one-dimensional many-body system in a quasiperiodic potential whose transport properties discontinuously change from localization to diffusion upon switching on interaction. This demonstrates an inherent instability of a possible many-body localization in a quasiperiodic potential at small interactions. We also show how the transport properties can be strongly modified by engineering potential at only a few lattice sites.

scholarly journals Perturbation Independent Decay of the Loschmidt Echo in a Many-Body System

2020 ◽  
Vol 124 (3) ◽  
Author(s):  
C. M. Sánchez ◽  
A. K. Chattah ◽  
K. X. Wei ◽  
L. Buljubasich ◽  
P. Cappellaro ◽  
...  
Keyword(s):  
Body System ◽  
Many Body ◽  
Loschmidt Echo

scholarly journals Loschmidt echo in many-spin systems: contrasting time scales of local and global measurements

2016 ◽  
Vol 374 (2069) ◽  
pp. 20150163 ◽  
Author(s):  
Pablo R. Zangara ◽  
Denise Bendersky ◽  
Patricia R. Levstein ◽  
Horacio M. Pastawski
Keyword(s):  
Time Scales ◽  
Time Scale ◽  
Simultaneous Occurrence ◽  
Many Body ◽  
General Picture ◽  
Single Spin ◽  
Complex Processes ◽  
Reversal Procedure ◽  
Loschmidt Echo ◽  
Short Time

A local excitation in a quantum many-spin system evolves deterministically. A time-reversal procedure, involving the inversion of the signs of every energy and interaction, should produce the excitation revival. This idea, experimentally coined in nuclear magnetic resonance, embodies the concept of the Loschmidt echo (LE). While such an implementation involves a single spin autocorrelation M 1,1 , i.e. a local LE, theoretical efforts have focused on the study of the recovery probability of a complete many-body state, referred to here as global or many-body LE M MB . Here, we analyse the relation between these magnitudes, with regard to their characteristic time scales and their dependence on the number of spins N . We show that the global LE can be understood, to some extent, as the simultaneous occurrence of N independent local LEs, i.e. M MB ∼( M 1,1 ) N /4 . This extensive hypothesis is exact for very short times and confirmed numerically beyond such a regime. Furthermore, we discuss a general picture of the decay of M 1,1 as a consequence of the interplay between the time scale that characterizes the reversible interactions ( T 2 ) and that of the perturbation ( τ Σ ). Our analysis suggests that the short-time decay, characterized by the time scale τ Σ , is greatly enhanced by the complex processes that occur beyond T 2 . This would ultimately lead to the experimentally observed T 3 , which was found to be roughly independent of τ Σ but closely tied to T 2 .

scholarly journals Loschmidt echo in many-body localized phases

2017 ◽  
Vol 96 (1) ◽  
Author(s):  
Maksym Serbyn ◽  
Dmitry A. Abanin
Keyword(s):  
Many Body ◽  
Loschmidt Echo

Convective Wave Equation and Time Reversal Process for Source Refocusing

2018 ◽  
Vol 26 (02) ◽  
pp. 1850016 ◽  
Author(s):  
Adar Kahana ◽  
Eli Turkel ◽  
Dan Givoli
Keyword(s):  
Wave Equation ◽  
Time Reversal ◽  
Absorbing Boundary Conditions ◽  
Acoustic Wave Equation ◽  
Absorbing Boundary ◽  
Small Perturbations ◽  
Compact Region ◽  
Noisy Information ◽  
Ill Posed ◽  
Moving Media

The convective wave equation deals with wave propagation in a moving media. We focus on the underwater acoustic wave equation where the convective element is the flow of water inside a river, along its length. The main thrust of this paper is the ill-posed “refocusing” problem. The initial condition simulates an explosion in a small compact region and the response is recorded over time at several microphones. Having only partial and noisy information we expect that small perturbations will destroy the ability to recover the complete initial data. We use the time reversal (TR) technique to determine the location of the original explosion, given limited spatial observations. We test the effectiveness of this scheme under conditions including dissipation, dispersion, etc. We use finite differences and implement absorbing boundary conditions to simulate an unbounded region.

Sign in / Sign up

Export Citation Format

Share Document