Rapid ramps across the BEC-BCS crossover: a novel route to measuring the superfluid gap

Abstract

We investigate the response of superfluid Fermi gases to rapid changes of the three-dimensional s-wave scattering length a by solving the time-dependent Bogoliubov-de Gennes equations. In general the magnitude of the order parameter |Δ| performs oscillations, which are sometimes called the "Higgs" mode, with the angular frequency 2 Δ_{gap}/ \hbar, where Δ_{gap} is the gap in the spectrum of fermionic excitations. Firstly, we excite the oscillations with a linear ramp of 1/a and study the evolution of |Δ|. Secondly, we continously drive the system with a sinusoidal modulation of 1/a. In the first case, the oscillations in |Δ| damp according to a power law. In the second case, the continued driving causes revivals in the oscillations. In both cases, the excitation of the oscillations causes a reduction in the time-averaged value of |Δ|. We propose two experimental protocols, based around the two approaches, to measure the frequency and damping of the oscillations, and hence Δ_{gap}.

7 pages, 7 figures

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• Nonlinear Response of Diffusive Superconductors to $ac$-electromagnetic Fields
• Engineering Higgs dynamics by spectral singularities
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• Generation and decay of Higgs mode in a strongly interacting Fermi gas
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• Exciting the Higgs mode in a strongly-interacting Fermi gas by interaction modulation
• Probing two Higgs oscillations in a one-dimensional Fermi superfluid with Raman-type spin-orbit coupling
• Decay and revival of a transient trapped Fermi condensate
• Pairing Dynamics of Polar States in a Quenched p-wave Superfluid Fermi Gas
• A Novel Route to Reach a $p$-wave Superfluid Fermi Gas
• Exciting the long-lived Higgs mode in superfluid Fermi gases with particle removal
• Slow interaction quench in BCS superconductors: emergence of pre-formed pairs
• Quenched dynamics and pattern formation in clean and disordered Bogoliubov-de Gennes superconductors
• Emergence of spatial patterns and synchronization in superconducting time crystals
• Higgs response and pair condensation energy in superfluid nuclei
• Sudden-quench dynamics of Bardeen-Cooper-Schrieffer states in deep optical lattices
• Spectrum of density, spin and pairing fluctuations of an attractive two-dimensional Fermi gas
• Probing pair correlations in Fermi gases with Ramsey-Bragg interferometry
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• Higgs oscillations in a unitary Fermi superfluid
• Appropriate conditions to realize a $p$-wave superfluid state starting from a spin-orbit coupled $s$-wave superfluid Fermi gas