Abstract

We explore the effect of using two-dimensional matter-wave vortices to confine an ensemble of bosonic quantum impurities. This is modelled theoretically using a mass-imbalanced homogeneous two component Gross-Pitaevskii equation where each component has independent atom numbers and equal atomic masses. By changing the mass imbalance of our system we find the shape of the vortices are deformed even at modest imbalances, leading to barrel shaped vortices; which we quantify using a multi-component variational approach. The energy of impurity carrying vortex pairs are computed, revealing a mass-dependent energy splitting. We then compute the excited states of the impurity, which we in turn use to construct `covalent bonds' for vortex pairs. Our work opens a new route to simulating synthetic chemical reactions with superfluid systems.

Highlights

  • Quantized vortices represent the fundamental excitations of superfluids—atomic gases formed from interacting particles that exhibit nonviscous transport phenomena

  • To this, experiments with binary condensates have achieved the trapping of one matter wave inside another; in Ref. [9] a degenerate Fermi gas formed of 6Li atoms was confined inside a Bose-Einstein condensate of 133Cs atoms

  • To understand the physical behavior of the coupled superfluid-impurity system, we perform numerical simulations of the Gross-Pitaevskii model represented by Eqs. (1a) and (1b), subject to the constraint that the phase distribution θ1(x, y) of the first component satisfies

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Summary

INTRODUCTION

Quantized vortices represent the fundamental excitations of superfluids—atomic gases formed from interacting particles that exhibit nonviscous transport phenomena. Atomic Bose-Einstein condensates represent exceptionally pure physical systems, since it is possible to experimentally realize ground states with almost no noncondensate atoms present. This gives a unique opportunity to study the role of impurities in these systems, with recent pioneering experiments realizing both bosonic [6,7] and fermionic [8] polarons. Quantum mechanical gases manifest superfluidity by the nucleation of quantized vortices when the gas undergoes rotation This leads to the formation of the Abrikosov lattice at equilibrium; recent work has revealed that homogeneous [21], multi-component [22,23], and densitydependent [24] gauge theories all exhibit novel vortex configurations.

THEORETICAL MODEL
NUMERICAL RESULTS
Single vortices
Variational calculation
Vortex pairs
COVALENT BONDS BETWEEN WELL-SEPARATED VORTICES
Padé approximation for a single vortex
Impurity potential model
Single vortex bound states
Covalent bonds between two vortices
Bonding at finite angular momentum
CONCLUSIONS
Full Text
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