Disentangling quantum matter with measurements

TL;DR

This paper introduces a measurement-based approach to characterize complex quantum states by disentangling components, revealing insights into phases like topological matter, heavy fermions, and scar states.

Contribution

It develops a protocol using measurements to analyze and bound entanglement in multi-component quantum systems, providing a new tool for understanding quantum phases.

Findings

Bound entanglement entropy after measurements in various models.

Applied protocol to topological phases, heavy fermions, and scar states.

Demonstrated the protocol's effectiveness in characterizing quantum matter.

Abstract

Measurements destroy entanglement. Building on ideas used to study `quantum disentangled liquids', we explore the use of this effect to characterize states of matter. We focus on systems with multiple components, such as charge and spin in a Hubbard model, or local moments and conduction electrons in a Kondo lattice model. In such systems, measurements of (a subset of) one of the components can leave behind a quantum state of the other that is easy to understand, for example in terms of scaling of entanglement entropy of subregions. We bound the outcome of this protocol, for any choice of measurement, in terms of more standard information-theoretic quantities. We apply this quantum disentangling protocol to several problems of physical interest, including gapless topological phases, heavy fermions, and scar states in Hubbard model.