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Higgs Oscillations in a Unitary Fermi Superfluid
P Dyke1, S Musolino2, H Kurkjian3
1Optical Sciences Centre, ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Swinburne University of Technology, Melbourne, Victoria 3122, Australia.
Physical Review Letters
|June 15, 2024
Summary
Researchers directly observed amplitude fluctuations in atomic Fermi gases, a key but elusive excitation in superfluids. This breakthrough in understanding states of matter opens new avenues for studying quantum phenomena.
Area of Science:
- Condensed Matter Physics
- Quantum Gases
- Superfluidity
Background:
- Symmetry-breaking phase transitions are fundamental to states of matter.
- Continuous symmetry breaking creates excitations linked to order parameter fluctuations.
- In superfluids, phase and amplitude fluctuations yield distinct collective branches, but amplitude fluctuations are hard to detect.
Purpose of the Study:
- To directly excite and measure amplitude oscillations in an atomic Fermi gas.
- To investigate the properties and behavior of these elusive excitations.
Main Methods:
- Excitation of amplitude oscillations via an interaction quench in a resonant Fermi gas.
- Time-resolved measurement using Bragg spectroscopy, sensitive to order parameter amplitude.
- Analysis of the time-resolved response to reveal oscillation frequency and magnitude.
Main Results:
- Direct observation of amplitude oscillations at twice the superfluid gap frequency.
- Strong temperature dependence of the oscillatory response magnitude.
- Observed decay of oscillations faster than predicted by time-dependent Bardeen-Cooper-Schrieffer theory.
Conclusions:
- Demonstrated a method to directly generate and probe amplitude fluctuations in superfluids.
- Provided experimental evidence for amplitude oscillations and their unique characteristics.
- Highlighted discrepancies with current theory, suggesting refinements are needed for superfluid dynamics.
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