Impurity coupled to an artificial magnetic field in a Fermi gas in a ring trap
Author
Ünal, F. N.
Hetényi, B.
Oktel, M. Ö.
Date
2015Source Title
Physical Review A
Print ISSN
2469-9926
Electronic ISSN
2469-9934
Publisher
American Physical Society
Volume
91
Issue
5
Pages
053625-1 - 053625-11
Language
English
Type
ArticleItem Usage Stats
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Abstract
The dynamics of a single impurity interacting with a many-particle background is one of the central problems of condensed-matter physics. Recent progress in ultracold-atom experiments makes it possible to control this dynamics by coupling an artificial gauge field specifically to the impurity. In this paper, we consider a narrow toroidal trap in which a Fermi gas is interacting with a single atom. We show that an external magnetic field coupled to the impurity is a versatile tool to probe the impurity dynamics. Using a Bethe ansatz, we calculate the eigenstates and corresponding energies exactly as a function of the flux through the trap. Adiabatic change of flux connects the ground state to excited states due to flux quantization. For repulsive interactions, the impurity disturbs the Fermi sea by dragging the fermions whose momentum matches the flux. This drag transfers momentum from the impurity to the background and increases the effective mass. The effective mass saturates to the total mass of the system for infinitely repulsive interactions. For attractive interactions, the drag again increases the effective mass which quickly saturates to twice the mass of a single particle as a dimer of the impurity and one fermion is formed. For excited states with momentum comparable to number of particles, effective mass shows a resonant behavior. We argue that standard tools in cold-atom experiments can be used to test these predictions.
Keywords
AtomsCondensed matter physics
Drag
Dynamics
Eigenvalues and eigenfunctions
Electron gas
Excited states
Ground state
Magnetic fields
Momentum
Adiabatic changes
Attractive interactions
Central problems
External magnetic field
Recent progress
Repulsive interactions
Resonant behavior
Ultracold atoms
Fermions