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arXiv · 1510.00987

Few-body precursor of the Higgs mode in a superfluid Fermi gas

J. Bjerlin·S. M. Reimann·G. M. Bruun
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Abstract

We demonstrate that an undamped few-body precursor of the Higgs mode can be investigated in a harmonically trapped Fermi gas. Using exact diagonalisation, the lowest monopole mode frequency is shown to depend non-monotonically on the interaction strength, having a minimum in a crossover region. The minimum deepens with increasing particle number, reflecting that the mode is the few-body analogue of a many-body Higgs mode in the superfluid phase, which has a vanishing frequency at the quantum phase transition point to the normal phase. We show that this mode mainly consists of coherent excitations of time-reversed pairs, and that it can be selectively excited by modulating the interaction strength, using for instance a Feshbach resonance in cold atomic gases.

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J. Bjerlin, S. M. Reimann, G. M. Bruun. 2015-10-04. Few-body precursor of the Higgs mode in a superfluid Fermi gas. https://doi.org/10.1103/physrevlett.116.155302

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