Work

Active Quantum Matter from Monitored Pure-State Dynamics

Year: 2026

Type: article

Abstract: Quantum many-body systems coupled to out-of-equilibrium reservoirs can behave as active matter and exhibit signs of flocking. However, the resulting steady states are highly mixed and carry only weak quantum signatures. We show that signatures of active matter also arise in ensembles of pure states undergoing monitored quantum dynamics. We consider a spinful Luttinger liquid subject to measurement processes that shuffle spin-up particles to the left and spin-down particles to the right. For weak monitoring strengths and ferromagnetic spin interactions, we find power-law quantum correlations between spin density and charge current, which we identify as a hallmark of active quantum matter. The monitoring plays a dual role, generating the quantum active correlations for weak strengths while driving a Berezinskii-Kosterlitz-Thouless phase transition to a short-range correlated state at larger strengths.

Source: Physical Review Letters

DOI: 10.1103/zhdk-kgzx

Authors: Jacob F. Steiner, Felix von Oppen, Reinhold Egger

Institutions: California Institute of Technology, Freie Universität Berlin, Heinrich Heine University Düsseldorf

Language: English

Topic: Quantum many-body systems

Subfield: Atomic and Molecular Physics, and Optics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,750

Funders: Deutsche Forschungsgemeinschaft, Multidisciplinary University Research Initiative, Air Force Office of Scientific Research