Auxiliary-state facilitated phase synchronization phenomena in isolated spin systems

TL;DR

This paper explores quantum phase synchronization in an effective spin-1 system, showing how auxiliary states and their couplings can control synchronization phenomena with potential applications in quantum technology.

Contribution

It introduces a novel effective spin-1 model with controllable synchronization via auxiliary states, highlighting the role of dissipative processes in quantum synchronization.

Findings

Synchronization controlled by coupling phases.

Dissipative decay out of the limit cycle is crucial.

Parameter regime where dissipation alone governs synchronization.

Abstract

Extending classical synchronization to the quantum domain is of great interest both from the fundamental physics point of view and with a view toward quantum technology applications. This work characterizes phase synchronization of an effective spin-1 system, which is realized by coupling three quantum states with infinite lifetime to auxiliary excited states that have a finite lifetime. Integrating out the excited states, the effective spin-1 model features coherent and incoherent effective couplings. Our key findings are: (i) Phase synchronization can be controlled by adjusting the phases of the couplings to the excited states. (ii) Unlike in the paradigmatic spin-1 system studied in the literature, where the dissipative couplings describe decay into the limit cycle state, the effective spin-1 model investigated in this work is governed by a competition between dissipative decay into and out of the limit cycle state, with the dissipative decay out of the limit cycle state playing a critical role. (iii) We identify a parameter regime where phase synchronization of the effective spin-1 system is -- in the absence of coherent effective couplings -- governed entirely by the effective dissipators. The effective spin-1 model is benchmarked through comparisons with master equation calculations for the full Hilbert space. Physical insights are gained through analytical perturbation theory calculations. Our findings, which are expected to hold for a broad class of energy level and coupling schemes, are demonstrated using hyperfine states of $^{87}$Rb.