Quantum Monte Carlo simulation of BEC-impurity tunneling

A. S. Popova, V. V. Tiunova, and A. N. Rubtsov
Phys. Rev. B 103, 155406 – Published 9 April 2021

Abstract

Polaron tunneling is a prominent example of a problem characterized by different energy scales, for which the standard quantum Monte Carlo methods face a slowdown problem. We propose a quantum-tunneling Monte Carlo (QTMC) method which is free from this issue and can be used for a wide range of tunneling phenomena. We apply it to study an impurity interacting with a one-dimensional Bose-Einstein condensate and simultaneously trapped in an external double-well potential. Our scheme works for an arbitrary coupling between the particle and condensate and, at the same time, allows for an account of tunneling effects. We discover two distinct quasiparticle peaks associated, respectively, with the phonon-assisted tunneling and the self-trapping of the impurity, which are in a crossover regime for the system modeled. We observe and analyze changes in the weights and spectral positions of the peaks (or, equally, effective masses of the quasiparticles) when the coupling strength is increased. Possible experimental realizations using cold atoms are discussed.

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  • Received 23 November 2020
  • Revised 1 March 2021
  • Accepted 31 March 2021

DOI:https://doi.org/10.1103/PhysRevB.103.155406

©2021 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

A. S. Popova1,*, V. V. Tiunova1, and A. N. Rubtsov1,2

  • 1Russian Quantum Center, Bolshoy Bulvar 30, Building 1, Skolkovo, Moscow 121205, Russia
  • 2Department of Physics, Lomonosov Moscow State University, Leninskie gory 1, Moscow 119991, Russia

  • *chertkova.anastasia.phys@gmail.com

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Issue

Vol. 103, Iss. 15 — 15 April 2021

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