Quantum critical behavior influenced by measurement backaction in ultracold gases

TL;DR

This paper explores how measurement backaction in ultracold gases modifies quantum critical points and phases, revealing new universality classes through theoretical analysis and proposing experimental verification.

Contribution

It introduces a theoretical framework for understanding measurement-induced shifts in quantum criticality and identifies a new critical phase beyond standard universality classes.

Findings

Measurement backaction shifts the superfluid--Mott-insulator transition point.

A new critical behavior beyond the Tomonaga-Luttinger liquid universality class.

Proposal for experimental realization using quantum gas microscopes.

Abstract

Recent realizations of quantum gas microscope offer the possibility of continuous monitoring of the dynamics of a quantum many-body system at the single-particle level. By analyzing effective non-Hermitian Hamiltonians of interacting bosons in an optical lattice and continuum, we demonstrate that the backaction of quantum measurement shifts the quantum critical point and gives rise to a unique critical phase beyond the terrain of the standard universality class. We perform mean-field and strong-coupling-expansion analyses and show that non-Hermitian contributions shift the superfluid--to-Mott-insulator transition point. Using a low-energy effective field theory, we discuss critical behavior of the one-dimensional interacting Bose gas subject to the measurement backaction. We derive an exact ground state of the effective non-Hermitian Hamiltonian and find a unique critical behavior beyond the Tomonaga-Luttinger liquid universality class. We propose experimental implementations of post-selections using quantum gas microscopes to simulate the non-Hermitian dynamics and argue that our results can be investigated with current experimental techniques in ultracold atoms.