Thermodynamic and Real-time Dynamic Properties of Complex Sachdev-Ye-Kitaev Model

TL;DR

This paper investigates the thermodynamic and dynamic properties of the complex Sachdev-Ye-Kitaev model, revealing phase transition behaviors analogous to van der Waals systems and analyzing the effects of chemical potential on spectral and dynamical features.

Contribution

It provides a detailed numerical and analytical study of the cSYK model's phase transitions, spectral properties, and real-time dynamics influenced by chemical potential, highlighting novel critical phenomena.

Findings

cSYK exhibits van der Waals-like first-order phase transition.

Chemical potential induces significant changes in spectral and energy gap properties.

Spectral functions transition from continuous to discrete energy levels.

Abstract

We study the complex Sachdev-Ye-Kitaev (cSYK) numerically and investigate thermodynamic behavior of cSYK model across varying chemical potentials. We discover that the cSYK model remarkably mirrors the first-order phase transition seen in the van der Waals-Maxwell system, culminating at a non-mean-field critical point with distinctively different critical exponents. We analyze in detail the similarity between the van der Waals phase transition and the cSYK model, and further explore the mechanism by which the chemical potential drives the phase transition in the system. Exact diagonalization for the cSYK model reveals the significant impact of chemical potential on energy distribution, with observable energy gaps in the gapped phase. Quantum chaos indicators, including spectral form factors, suggest more stable energy states in the neutral case. Real-time dynamics, analyzed via analytical continuation of Schwinger-Dyson equations, show rapid decay in the gapless phase and prolonged oscillation lifetimes in the gapped regime. Spectral functions imply a shift from a continuous to a discrete energy level distribution, emphasizing the critical role of chemical potential in shaping spectral properties.