# Thermometry with spin-dependent lattices

## TL;DR

The paper introduces a novel thermometry method for ultracold atom gases in spin-dependent lattices using impurity atoms as temperature probes, supported by theoretical analysis and proof-of-principle experiments.

## Contribution

It presents a new impurity-based thermometry technique for strongly correlated ultracold gases in spin-dependent lattices, including the first realization of a 3D spin-dependent lattice in this regime.

## Key findings

- Impurity atoms can accurately measure temperature via time-of-flight expansion.
- First experimental realization of a 3D spin-dependent lattice in the strongly correlated regime.
- The method offers a new approach to study thermalization in isolated quantum systems.

## Abstract

We propose a method for measuring the temperature of strongly correlated phases of ultracold atom gases confined in spin-dependent optical lattices. In this technique, a small number of "impurity" atoms--trapped in a state that does not experience the lattice potential--are in thermal contact with atoms bound to the lattice. The impurity serves as a thermometer for the system because its temperature can be straightforwardly measured using time-of-flight expansion velocity. This technique may be useful for resolving many open questions regarding thermalization in these isolated systems. We discuss the theory behind this method and demonstrate proof-of-principle experiments, including the first realization of a 3D spin-dependent lattice in the strongly correlated regime.