Discrete Time Crystal Phase as a Resource for Quantum Enhanced Sensing

TL;DR

This paper demonstrates that a disorder-free discrete time crystal can serve as a robust quantum sensor with enhanced sensitivity, exhibiting a sharp phase transition that affects its sensing performance.

Contribution

It introduces a novel mechanism to generate stable discrete time crystals in disorder-free systems and explores their potential for quantum sensing applications.

Findings

Strong quantum-enhanced sensitivity in the time crystal phase

Sharp second-order phase transition affecting sensing performance

Performance robustness against initial state variations and pulse imperfections

Abstract

Discrete time crystals are a special phase of matter in which time translational symmetry is broken through a periodic driving pulse. Here, we first propose and characterize an effective mechanism to generate a stable discrete time crystal phase in a disorder-free many-body system with indefinite persistent oscillations even in finite-size systems. Then we explore the sensing capability of this system to measure the spin exchange coupling. The results show strong quantum-enhanced sensitivity throughout the time crystal phase. As the spin exchange coupling varies, the system goes through a sharp phase transition and enters a non-time crystal phase in which the performance of the probe considerably decreases. We characterize this phase transition as a second-order type and determine its critical properties through a comprehensive finite-size scaling analysis. The performance is independent of the initial states and may even benefit from imperfections in the driving pulse. A simple set of projective measurements can capture the quantum-enhanced sensitivity.