Anomalous diffusion and localization in a disorder-free atomic mixture

Fuente: arXiv
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Autori principali: Finelli, Stefano, Restivo, Beatrice, Ciamei, Alessio, Trenkwalder, Andreas, Inguscio, Massimo, Petrov, Dmitry S., Skipetrov, Sergey E., Zaccanti, Matteo
Natura: Preprint
Pubblicazione: 2026
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author Finelli, Stefano
Restivo, Beatrice
Ciamei, Alessio
Trenkwalder, Andreas
Inguscio, Massimo
Petrov, Dmitry S.
Skipetrov, Sergey E.
Zaccanti, Matteo
author_facet Finelli, Stefano
Restivo, Beatrice
Ciamei, Alessio
Trenkwalder, Andreas
Inguscio, Massimo
Petrov, Dmitry S.
Skipetrov, Sergey E.
Zaccanti, Matteo
contents The concept of random walk, in which particles or waves undergo multiple collisions with the microscopic constituents of a surrounding medium, is central to understanding diffusive transport across many research areas. However, this paradigm may break down in complex systems, where quantum interference and memory effects render the particle propagation anomalous, often fostering localization. Here we report on the observation of such anomalous dynamics in a minimal setting: an ultracold mass-imbalanced mixture of two fermionic gases in three dimensions. We release light impurities into a gas of heavier atoms and follow their evolution across different collisional regimes. Under strong interspecies interactions, by lowering the temperature we unveil a crossover from normal diffusion to subdiffusion. Simultaneously, a localized fraction of the light gas emerges, displaying no discernible dynamics over hundreds of collisions. Our findings, incompatible with the conventional Fermi-liquid picture, are instead captured by a model of an atom propagating through a (quasi-)static disordered landscape of point-like scatterers. These results highlight the key role of quantum interference in our mixture, which emerges as a versatile platform for exploring disorder-free localization phenomena.
format Preprint
id arxiv_https___arxiv_org_abs_2601_13226
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Anomalous diffusion and localization in a disorder-free atomic mixture
Finelli, Stefano
Restivo, Beatrice
Ciamei, Alessio
Trenkwalder, Andreas
Inguscio, Massimo
Petrov, Dmitry S.
Skipetrov, Sergey E.
Zaccanti, Matteo
Quantum Gases
Atomic Physics
Quantum Physics
The concept of random walk, in which particles or waves undergo multiple collisions with the microscopic constituents of a surrounding medium, is central to understanding diffusive transport across many research areas. However, this paradigm may break down in complex systems, where quantum interference and memory effects render the particle propagation anomalous, often fostering localization. Here we report on the observation of such anomalous dynamics in a minimal setting: an ultracold mass-imbalanced mixture of two fermionic gases in three dimensions. We release light impurities into a gas of heavier atoms and follow their evolution across different collisional regimes. Under strong interspecies interactions, by lowering the temperature we unveil a crossover from normal diffusion to subdiffusion. Simultaneously, a localized fraction of the light gas emerges, displaying no discernible dynamics over hundreds of collisions. Our findings, incompatible with the conventional Fermi-liquid picture, are instead captured by a model of an atom propagating through a (quasi-)static disordered landscape of point-like scatterers. These results highlight the key role of quantum interference in our mixture, which emerges as a versatile platform for exploring disorder-free localization phenomena.
title Anomalous diffusion and localization in a disorder-free atomic mixture
topic Quantum Gases
Atomic Physics
Quantum Physics
url https://arxiv.org/abs/2601.13226