Quantum probe spectroscopy for cold atomic systems

TL;DR

This paper introduces a nondestructive quantum probe spectroscopy method that uses a two-level impurity to extract local excitation spectra of cold atomic systems on optical lattices, even under realistic noise conditions.

Contribution

It presents a novel approach to probe local excitations in quantum gases using impurity dynamics, enabling broad energy spectrum analysis without destroying the system.

Findings

Successfully simulated impurity-based spectroscopy for quantum lattice systems

Demonstrated robustness of the method under realistic dephasing noise

Identified practical limits on probe dephasing for spectral resolution

Abstract

We study a two-level impurity coupled locally to a quantum gas on an optical lattice. For state-dependent interactions between the impurity and the gas, we show that its evolution encodes information on the local excitation spectrum of gas at the coupling site. Based on this, we design a nondestructive method to probe the system's excitations in a broad range of energies by measuring the state of the probe using standard atom optics methods. We illustrate our findings with numerical simulations for quantum lattice systems, including realistic dephasing noise on the quantum probe, and discuss practical limits on the probe dephasing rate to fully resolve both regular and chaotic spectra.