Probing Yang-Lee Edge Singularity by Central Spin Decoherence

TL;DR

This paper demonstrates that the quantum coherence of a probe spin can be used to experimentally access and analyze the Yang-Lee edge singularity in finite-size Ising systems, revealing critical points and exponents.

Contribution

It introduces a universal scaling method using probe spin coherence to study Yang-Lee edge singularities in finite systems, enabling experimental investigation of these complex phase transitions.

Findings

Quantum coherence exhibits universal scaling near the Yang-Lee edge.

Critical points and exponents can be extracted from finite-size measurements.

Provides a practical approach for studying phase transitions at complex parameters.

Abstract

Yang-Lee edge singularities are the branch point of the free energy on the complex plane of physical parameters and were shown to be the simplest universality class of phase transitions. However, the Yang-Lee edge singularities have not been regarded as experimentally observable since they occur at complex physical parameters, which are unphysical. A recent discovery about the relation between partition functions and probe spin coherence makes it experimentally feasible to access the complex plane of physical parameters. However, how to extract the critical point and the critical exponent of Yang-Lee edge singularities in many-body systems, which occurs only at thermodynamic limit, has still been elusive. Here we show that the quantum coherence of a probe spin coupled to finite-size Ising-type spin systems presents universal scaling behavior near the Yang-Lee edge singularity. The finite-size scaling behavior of quantum coherence of the probe spin predicts that one can extract the critical point and the critical exponent of the Yang-Lee edge singularity of Ising-type spin system in the thermodynamic limit from the spin coherence measurement of the probe spin coupled to finite Ising-type spin systems. This finding provides a practical approach to studying the nature of Yang-Lee edge singularities of many-body systems.