Real-Time Simulation of Large Open Quantum Spin Systems driven by Measurements

TL;DR

This paper models the real-time evolution of large open quantum spin systems driven by measurements, demonstrating a sign-problem-free approach to study measurement-induced phase transitions in a 2D Heisenberg antiferromagnet.

Contribution

It introduces an efficient cluster algorithm for simulating measurement-driven quantum dynamics without sign problems, enabling analysis of phase transitions in large 2D spin systems.

Findings

Measurement-driven dynamics induce a disordered phase.

The simulation method avoids sign problems in real-time path integrals.

Continuous monitoring leads to a phase transition in the system.

Abstract

We consider a large quantum system with spins $\frac{1}{2}$ whose dynamics is driven entirely by measurements of the total spin of spin pairs. This gives rise to a dissipative coupling to the environment. When one averages over the measurement results, the corresponding real-time path integral does not suffer from a sign problem. Using an efficient cluster algorithm, we study the real-time evolution of a 2-d Heisenberg antiferromagnet, which is driven to a disordered phase, either by sporadic measurements or by continuous monitoring described by Lindblad evolution.