Simulating Zeno physics by a quantum quench with superconducting circuits

Abstract

Studying out-of-equilibrium physics in quantum systems under quantum quench is of vast experimental and theoretical interests. Using periodic quantum quenches, we present an experimentally accessible scheme to simulate the quantum Zeno and anti-Zeno effects in an open quantum system of a single superconducting qubit interacting with an array of transmission line resonators. The scheme is based on the following two observations: Firstly, compared with conventional systems, the short-time non-exponential decay in our superconducting circuit system is readily observed; and secondly, a quench-off process mimics an ideal projective measurement when its time duration is sufficiently long. Our results show the active role of quantum quench in quantum simulation and control.PACS numbers: 03.67.Ac., 03.65. Xp, 03.67.Pp, Introduction.-Recently, there has been an increasing interest in exploring quench dynamics in quantum systems, in which a parameter of the system is tuned abruptly at specific time [1]. Interest in this area has been evoked principally by several experimental realizations such as in ultra-cold atoms [2,3], where the high controllability in tuning parameters of the system has been achieved and the realization of different external sudden interruptions has been made accessible. Many important issues, for example the equilibration process and the relationship between thermalization and the integrability of many-body systems under quantum quench [4][5][6][7][8][9][10][11][12], have been investigated. So far, most of these works have focused on the ideal closed quantum systems. However, any realistic quantum system would become open due to the inevitable interaction with its surrounding environment, causing the so-called decoherence [13]. Studying quench dynamics in open system can not only cast better understanding on environment-induced decoherence effects under external interruptions but also give help in exploring potential strategies to control decoherence [14].

Giant atoms with time-dependent couplings

“…In view of this, we resort to a discrete version of the present model, where a two-level giant atom is coupled to a tight-binding lattice (e.g., one-dimensional array of coupled transmission line resonators [50,51]) with time-dependent strengths. In this case, the shorttime behavior can be clearly observed by directly solving the coupled-mode equations of the whole system [52,53]. Now the Hamiltonian of the system can be written as…”

“…Physically, this is because the memory of the lattice (i.e., the feedback from the lattice to the atom) tends to vanish for long enough quench off and the decay of the atom restarts with the short-time parabolic behavior at each quench-on time. That is to say, a coupling quench with large enough quench-off duration mimics an ideal observation which results in a "collapse" of the state [53]. From this perspective, the quench-on duration t ′ corresponds to the time interval between the measurements, while the quench-off duration t ′′ serves as the duration of each measurement.…”

Experimental protection against evolution of states in a subspace via a super-Zeno scheme on an NMR quantum information processor

“…Decoherence control in a superconducting qubit system has been proposed using the quantum Zeno effect [19]. Unlike the super-Zeno and dynamical decoupling schemes that are based on unitary pulses, the quantum Zeno effect achieves suppression of state evolution using projective measurements.…”

Floquet engineering to entanglement protection of distant nitrogen vacancy centers

“…Although the periodically driven systems have no stationary states usually existing in static systems, they have well defined quasi-stationary-state properties described by the Floquet eigenvalues (also called quasienergies). Through controlling the quasienergy spectrum of periodically driven systems, more colorful quasi-stationary-state behaviors and more non-trivial effects than the original static cases are expected [33][34][35][36][37][38][39].…”