Measurement-Induced Phase Transition in a Disordered XX Spin Chain: A Real-Space Renormalization Group Study

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Hauptverfasser: Tiwary, Siddharth, Moore, Joel E.
Format: Preprint
Veröffentlicht: 2025
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author Tiwary, Siddharth
Moore, Joel E.
author_facet Tiwary, Siddharth
Moore, Joel E.
contents Spin chains with quenched disorder exhibit rich critical behavior, often captured by real-space renormalization group (RSRG) techniques. However, the physics of such systems in the presence of random measurements (i.e., non-Hermitian dephasing) remains largely unexplored. The interplay between measurements and unitary dynamics gives rise to novel phases and phase transitions in monitored quantum systems. In this work, we investigate the disordered XX spin chain subject to stochastic local measurements in the $X$ and $Y$ bases. By mapping the monitored chain to a non-Hermitian spin ladder with complex couplings, we propose an RSRG-for-excited-states (RSRG-X) approach for this open-system setting. Our analysis reveals a new class of strongly disordered fixed points that emerge due to non-unitarity, broadening the landscape of critical phenomena accessible via RSRG.
format Preprint
id arxiv_https___arxiv_org_abs_2507_11957
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Measurement-Induced Phase Transition in a Disordered XX Spin Chain: A Real-Space Renormalization Group Study
Tiwary, Siddharth
Moore, Joel E.
Quantum Physics
Disordered Systems and Neural Networks
Statistical Mechanics
Spin chains with quenched disorder exhibit rich critical behavior, often captured by real-space renormalization group (RSRG) techniques. However, the physics of such systems in the presence of random measurements (i.e., non-Hermitian dephasing) remains largely unexplored. The interplay between measurements and unitary dynamics gives rise to novel phases and phase transitions in monitored quantum systems. In this work, we investigate the disordered XX spin chain subject to stochastic local measurements in the $X$ and $Y$ bases. By mapping the monitored chain to a non-Hermitian spin ladder with complex couplings, we propose an RSRG-for-excited-states (RSRG-X) approach for this open-system setting. Our analysis reveals a new class of strongly disordered fixed points that emerge due to non-unitarity, broadening the landscape of critical phenomena accessible via RSRG.
title Measurement-Induced Phase Transition in a Disordered XX Spin Chain: A Real-Space Renormalization Group Study
topic Quantum Physics
Disordered Systems and Neural Networks
Statistical Mechanics
url https://arxiv.org/abs/2507.11957