Prethermal Floquet time crystals in chiral multiferroic chains and applications as quantum sensors of AC fields

TL;DR

This paper investigates prethermal Floquet time crystals in disordered chiral multiferroic chains and demonstrates their potential as robust quantum sensors for AC fields, outperforming non-interacting spin sensors due to many-body effects.

Contribution

It introduces a model of disordered chiral multiferroic chains exhibiting prethermal Floquet time crystals and explores their application as quantum sensors with enhanced sensitivity.

Findings

The phase diagram characterizes magnetization, entanglement, and coherence dynamics.

The sensor surpasses the standard quantum limit during the prethermal regime.

The quantum Fisher information scales superlinearly with the number of spins.

Abstract

We study the emergence of prethermal Floquet Time Crystal (pFTC) in disordered chiral multiferroic chains. The model is an extension of the usual periodically driven nearest-neighbor disordered Heisenberg chain, with additional next-nearest-neighbor Heisenberg couplings and DMI interactions due to external magnetic and electric couplings. We derive the phase diagram of the model, characterizing the magnetization, entanglement, and coherence dynamics of the system along the extended interactions. In addition, we explore the application of the pFTC as quantum sensors of AC fields. The sensor performance to estimate small AC fields is quantified through the quantum Fisher information (QFI) measure. The sensor offers several advantages as compared to those composed of non-interacting spins due to its intrinsic robustness, long coherent interrogation time, and many-body correlations. Specifically, the sensor can overcome the standard quantum limit ($\rm{SQL} \sim N t^2$) during the prethermal regime, reaching an optimum performance at the pFTC lifetime $t^*$, where the $\rm{QFI}/Nt^{*^2} \sim N^\alpha$ with $\alpha > 0$, scaling superlinarly with the number of spins. Different from \text{full} FTCs, the prethermal lifetime does not diverge in the thermodynamic limit, nevertheless it can be increasingly long with tuning system parameters.