# Feedback-Induced Quantum Phase Transitions Using Weak Measurements

## TL;DR

This paper demonstrates that feedback and weak measurements can induce quantum phase transitions with controllable properties, revealing new ways to manipulate quantum systems beyond traditional dissipative effects.

## Contribution

It introduces a novel approach to induce and control quantum phase transitions using feedback and weak measurements, highlighting their role in quantum fluctuation-driven critical phenomena.

## Key findings

- Feedback enables control over quantum critical exponents.
- Induces non-Markovian and nonlinear dynamics in quantum systems.
- Simulates effects akin to spin-bath problems and Floquet time crystals.

## Abstract

We show that applying feedback and weak measurements to a quantum system induces phase transitions beyond the dissipative ones. Feedback enables controlling essentially quantum properties of the transition, i.e., its critical exponent, as it is driven by the fundamental quantum fluctuations due to measurement. Feedback provides the non-Markovianity and nonlinearity to the hybrid quantum-classical system, and enables simulating effects similar to spin-bath problems and Floquet time crystals with tunable long-range (long-memory) interactions.