Angle-resolved photoemission spectroscopy with quantum gas microscopes

TL;DR

This paper proposes a method to measure momentum- and energy-resolved spectral functions in quantum gas microscopes, enabling insights into elementary excitations and fractionalization in many-body quantum systems.

Contribution

It introduces a novel measurement scheme for spectral functions in quantum gas microscopes, bridging a gap in experimental capabilities for studying many-body excitations.

Findings

Numerical calculation of single hole spectra in 1D $t-J$ models.

Identification of spectral weight asymmetry in isotropic Heisenberg chains.

Dependence of spectral features on magnetization and interaction anisotropy.

Abstract

Quantum gas microscopes are a promising tool to study interacting quantum many-body systems and bridge the gap between theoretical models and real materials. So far they were limited to measurements of instantaneous correlation functions of the form $\langle \hat{O}(t) \rangle$, even though extensions to frequency-resolved response functions $\langle \hat{O}(t) \hat{O}(0) \rangle$ would provide important information about the elementary excitations in a many-body system. For example, single particle spectral functions, which are usually measured using photoemission experiments in electron systems, contain direct information about fractionalization and the quasiparticle excitation spectrum. Here, we propose a measurement scheme to experimentally access the momentum and energy resolved spectral function in a quantum gas microscope with currently available techniques. As an example for possible applications, we numerically calculate the spectrum of a single hole excitation in one-dimensional $t-J$ models with isotropic and anisotropic antiferromagnetic couplings. A sharp asymmetry in the distribution of spectral weight appears when a hole is created in an isotropic Heisenberg spin chain. This effect slowly vanishes for anisotropic spin interactions and disappears completely in the case of pure Ising interactions. The asymmetry strongly depends on the total magnetization of the spin chain, which can be tuned in experiments with quantum gas microscopes. An intuitive picture for the observed behavior is provided by a slave-fermion mean field theory. The key properties of the spectra are visible at currently accessible temperatures.