Quantum criticality and universality in stationary state of long-range Kitaev model

TL;DR

This study reveals that quantum criticality and universality class signatures persist in the stationary states of a long-range Kitaev chain after quench protocols, regardless of the decay exponent of interactions.

Contribution

It demonstrates that quantum criticality and universality class indicators are retained in the stationary state of a long-range Kitaev model, even with algebraic decay of correlations at non-critical points.

Findings

Quantum criticality signatures are present in stationary states after quenches.

Effective central charge matches ground state values for different decay exponents.

Universality class information can be inferred from stationary state properties.

Abstract

We investigate the signature of quantum criticality in the long-time stationary state of the long-range Kitaev chain by performing various quench protocols. In this model, the pairing interaction decays with distance according to a power law with exponent $\alpha$. Using quantum information-theoretic measures, such as mutual information and logarithmic negativity, we show that, irrespective of the values of $\alpha$, critical-to-critical quench displays quantum criticality even in the stationary state. Remarkably, in the presence of long-range pairing interactions, where fermionic correlators decay algebraically even at non-critical points, signature of quantum criticality persists in the stationary state. Furthermore, the effective central charge, calculated from both mutual information and logarithmic negativity of stationary state following a critical-to-critical quench, agrees with the central charge of the corresponding ground states for both $\alpha = 0$ and $\alpha = 2$. Therefore, information of the universality class can be inferred from the stationary state.