Transport properties and thermopower of the spinful Sachdev-Ye-Kitaev dot

TL;DR

This paper investigates the transport and thermopower in a spinful SYK quantum dot coupled to leads, revealing non-Fermi liquid signatures and conditions for enhanced thermoelectric effects, using a non-equilibrium Keldysh approach.

Contribution

It provides analytical and numerical analysis of transport in a non-equilibrium, open SYK system without replica trick, highlighting distinctive non-Fermi liquid transport signatures.

Findings

Non-Fermi liquid signatures in conductance and thermopower.

Identification of coupling regimes with enhanced thermoelectric effects.

Analytical results for tunneling and zero-temperature limits.

Abstract

We study the electric and thermoelectric transport through a spinful complex Sachdev-Ye-Kitaev (SYK) quantum dot coupled to metallic leads, forming a N-SYK-N junction, by the Keldysh field theory approach. Unlike traditional equilibrium approaches, our formulation treats the system as an open, interacting quantum conductor under non-equilibrium conditions, without resorting to the replica trick. Starting from the exact Keldysh-Dyson equations, we derive analytical results for the tunneling and zero-temperature limits and perform a numerical analysis in the linear-response regime. We characterize the dependence of conductance, thermoelectric coefficient, and Seebeck effect on the particle-hole asymmetry parameter and coupling strength to the leads. Our results reveal distinctive non-Fermi liquid signatures of the SYK model in transport properties and identify coupling regimes where thermoelectric effects are enhanced, suggesting experimentally accessible fingerprints of SYK physics in mesoscopic systems.