Scale invariance of the polaron energy at the Mott-superfluid critical point

Fuente: arXiv
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Main Authors: Čufar, Matija, Alhyder, Ragheed, Bradly, C. J., Colussi, Victor E., Bruun, Georg M., Brand, Joachim, Recati, Alessio
Format: Preprint
Published: 2026
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author Čufar, Matija
Alhyder, Ragheed
Bradly, C. J.
Colussi, Victor E.
Bruun, Georg M.
Brand, Joachim
Recati, Alessio
author_facet Čufar, Matija
Alhyder, Ragheed
Bradly, C. J.
Colussi, Victor E.
Bruun, Georg M.
Brand, Joachim
Recati, Alessio
contents Continuous quantum phase transitions are characterized by an order parameter and correlation functions that are often challenging to access experimentally or in direct numerical simulations. The energy of an added impurity can on the other hand be probed by established polaron spectroscopy, or numerically with Monte Carlo methods. We provide evidence from ground-state quantum Monte Carlo calculations that the energy of a mobile impurity interacting weakly with a surrounding lattice Bose gas provides access to the critical behavior of the Mott insulator-superfluid phase transition. Finite-size scaling of the energy reveals that its value is scale invariant at the critical point of the quantum phase transition, and we extract a scaling exponent that is currently unexplained by theory. For a small lattice we further observe a flattening of the impurity-boson density-density correlations at the critical point, which hints at a divergence of a corresponding length scale in the thermodynamic limit. Our results suggest that impurity spectroscopy represents a useful way to probe the critical properties of quantum phase transitions in general.
format Preprint
id arxiv_https___arxiv_org_abs_2604_17824
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Scale invariance of the polaron energy at the Mott-superfluid critical point
Čufar, Matija
Alhyder, Ragheed
Bradly, C. J.
Colussi, Victor E.
Bruun, Georg M.
Brand, Joachim
Recati, Alessio
Quantum Gases
Computational Physics
Continuous quantum phase transitions are characterized by an order parameter and correlation functions that are often challenging to access experimentally or in direct numerical simulations. The energy of an added impurity can on the other hand be probed by established polaron spectroscopy, or numerically with Monte Carlo methods. We provide evidence from ground-state quantum Monte Carlo calculations that the energy of a mobile impurity interacting weakly with a surrounding lattice Bose gas provides access to the critical behavior of the Mott insulator-superfluid phase transition. Finite-size scaling of the energy reveals that its value is scale invariant at the critical point of the quantum phase transition, and we extract a scaling exponent that is currently unexplained by theory. For a small lattice we further observe a flattening of the impurity-boson density-density correlations at the critical point, which hints at a divergence of a corresponding length scale in the thermodynamic limit. Our results suggest that impurity spectroscopy represents a useful way to probe the critical properties of quantum phase transitions in general.
title Scale invariance of the polaron energy at the Mott-superfluid critical point
topic Quantum Gases
Computational Physics
url https://arxiv.org/abs/2604.17824