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Sk Anisur

Publications and source records attributed to Sk Anisur.

3 recordsLinked to original sources

Dissipation stabilizes Dicke Time Quasicrystals

Quasi-periodic driving protocols provide a powerful route to realize novel non-equilibrium phases of matter beyond the Floquet paradigm. However, these protocols inevitably lead to infinite-temperature heat death in isolated systems, which poses a major challenge to their experimental realization. We demonstrate that dissipation can be harnessed to stabilize quasi-periodically driven systems, enabling the realization of robust non-equilibrium phases. Using the paradigmatic open Dicke model, we provide a blueprint for realizing a stable time quasicrystal (TQC) by Fibonacci driving. This TQC is characterized by a robust sub-harmonic quasi-periodic response that is dictated by, but qualitatively distinct from the external Fibonacci drive. By directly analyzing the time evolution in the thermodynamic limit, we establish the existence of TQC order in this system for a wide parameter regime. We trace the origin of the stability of the TQC to the attractor structure induced by dissipation. Strikingly, the TQC order persists in the deep quantum regime with as few as two qubits. We systematically study the dependence of the TQC lifetime, $\tau^{\ast}$, on the number of qubits and demonstrate that $\tau^{\ast}$ increases monotonically with the system size. Crucially, the TQC is not observed in the absence of dissipation. Our work establishes dissipation as a mechanism for stabilizing non-equilibrium phases of matter under quasi-periodic drive.

quant-ph

Directional quantum walks of two bosons on the Hatano-Nelson lattice

We theoretically investigate the interplay of interactions and non-Hermiticity in the dynamics of two bosons on the one-dimensional Hatano-Nelson lattice with non-reciprocal tunneling. We find that the non-reciprocity in the tunneling leads to the formation of an asymmetric density cone during the time-evolution of the system; the degree of asymmetry can be tuned by tuning the non-reciprocity parameter, $\delta$. Next, we analyze the dynamics of this system in the presence of a static external force and demonstrate that non-Hermiticity leads to asymmetric two-particle Bloch oscillations. Interestingly, when $F=0$ ($F \ne 0$), strong interactions leads to the formation of an inner density-cone (density-hourglass) structure; this inner structure also becomes asymmetric in the presence of non-Hermiticity. We further analyze the spatial correlations and establish that the system exhibits non-reciprocal bunching (anti-bunching) in the presence of weak (strong) interactions. Finally, we examine the growth of the Quantum Fisher Information, $F_Q$, with time, and demonstrate that $F_Q \propto t^{\alpha}$ where $\alpha \sim 3$. This feature persists for both one- and two-particle walks, thereby demonstrating that this system can be employed as a quantum-enhanced sensor for detecting weak forces.

quant-ph

Quasi-Discrete Time Crystals in the quasiperiodically driven Lipkin-Meshkov-Glick model

A discrete time crystal (DTC) is a remarkable non-equilibrium phase of matter characterized by the persistent sub-harmonic oscillations of physical observables in periodically driven many-body systems. Motivated by the question of whether such a temporal periodic order can persist when the drive becomes aperiodic, we investigate the dynamics of a Lipkin-Meshkov-Glick model under quasiperiodic Thue-Morse (TM) driving. Intriguingly, this infinite-range-interacting spin system can host ``quasi-discrete time crystal" (quasi-DTC) phases characterized by periodic oscillations of the magnetization. We demonstrate that our model can host the quasi-DTC analog of both period-doubling DTCs as well as higher-order DTCs. These quasi-DTCs are robust to various perturbations, and they originate from the interplay of ``all-to-all" interactions and the recursive structure of the TM sequence. Our results suggest that quasi-periodic driving protocols can provide a promising route for realizing novel non-equilibrium phases of matter in long-range interacting systems.

cond-mat.quant-gas