Quantum Brownian Motion: proving that the Schmid transition belongs to the Berezinskii-Kosterlitz-Thouless universality class

Fuente: arXiv
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Main Authors: Capone, Francesco G., de Candia, Antonio, Cataudella, Vittorio, Fazio, Rosario, Nagaosa, Naoto, Perroni, Carmine Antonio, De Filippis, Giulio
Format: Preprint
Published: 2026
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author Capone, Francesco G.
de Candia, Antonio
Cataudella, Vittorio
Fazio, Rosario
Nagaosa, Naoto
Perroni, Carmine Antonio
De Filippis, Giulio
author_facet Capone, Francesco G.
de Candia, Antonio
Cataudella, Vittorio
Fazio, Rosario
Nagaosa, Naoto
Perroni, Carmine Antonio
De Filippis, Giulio
contents We investigate the equilibrium properties of a quantum Brownian particle moving in a periodic potential, specifically addressing the nature of the dissipation-driven Schmid transition in the Ohmic regime. By employing World-Line Monte Carlo in the path-integral formalism and introducing a specific binary order parameter, we demonstrate that the transition belongs to the Berezinskii-Kosterlitz-Thouless universality class. This classification is substantiated through finite-size scaling analysis that reveals the characteristic logarithmic decay of the correlation functions associated with the order parameter at the critical point. Quantum phase transition turns out to be extremely fragile: it disappears in both over- and sub-Ohmic dissipation regimes. Crucially, we find that the presence of the periodic potential does not alter the localization properties in the sub-Ohmic and super-Ohmic regimes, where the system exhibits the same qualitative behavior as the free quantum Brownian particle. These findings highlight that the emergence of critical behavior is strictly governed by the low-frequency form of the environmental spectral function, which determines the long-range temporal decay of the dissipative kernel.
format Preprint
id arxiv_https___arxiv_org_abs_2603_16227
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Quantum Brownian Motion: proving that the Schmid transition belongs to the Berezinskii-Kosterlitz-Thouless universality class
Capone, Francesco G.
de Candia, Antonio
Cataudella, Vittorio
Fazio, Rosario
Nagaosa, Naoto
Perroni, Carmine Antonio
De Filippis, Giulio
Statistical Mechanics
Superconductivity
Quantum Physics
We investigate the equilibrium properties of a quantum Brownian particle moving in a periodic potential, specifically addressing the nature of the dissipation-driven Schmid transition in the Ohmic regime. By employing World-Line Monte Carlo in the path-integral formalism and introducing a specific binary order parameter, we demonstrate that the transition belongs to the Berezinskii-Kosterlitz-Thouless universality class. This classification is substantiated through finite-size scaling analysis that reveals the characteristic logarithmic decay of the correlation functions associated with the order parameter at the critical point. Quantum phase transition turns out to be extremely fragile: it disappears in both over- and sub-Ohmic dissipation regimes. Crucially, we find that the presence of the periodic potential does not alter the localization properties in the sub-Ohmic and super-Ohmic regimes, where the system exhibits the same qualitative behavior as the free quantum Brownian particle. These findings highlight that the emergence of critical behavior is strictly governed by the low-frequency form of the environmental spectral function, which determines the long-range temporal decay of the dissipative kernel.
title Quantum Brownian Motion: proving that the Schmid transition belongs to the Berezinskii-Kosterlitz-Thouless universality class
topic Statistical Mechanics
Superconductivity
Quantum Physics
url https://arxiv.org/abs/2603.16227