# Exact large deviation function of spin current for the one dimensional XX spin chain with domain wall initial condition

## TL;DR

This paper derives an exact large deviation function for spin current fluctuations in a 1D XX spin chain with domain wall initial conditions, using determinant formulas and Coulomb gas methods, validated by DMRG.

## Contribution

It provides the first exact analytical expression for the large deviation function of spin current in this model, advancing understanding of quantum spin transport.

## Key findings

- Exact large deviation function derived
- Determinant representation with Bessel kernel obtained
- Results confirmed by DMRG simulations

## Abstract

We investigate the fluctuations of the spin current for the one dimensional XX spin chain starting from the domain wall initial condition. The generating function of the current is shown to be written as a determinant with the Bessel kernel. An exact analytical expression for the large deviation function is obtained by applying the Coulomb gas method. Our results are also compared with DMRG calculations.