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 2Δgap/ℏ, where Δgap is the gap in the spectrum of fermionic excitations. First, we excite the oscillations with a linear ramp of 1/a and study the evolution of |Δ|. Second, 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 Δgap.

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

Scott, Robin George;Dalfovo, Franco;L. P. Pitaevskii;Stringari, Sandro
2012-01-01

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 2Δgap/ℏ, where Δgap is the gap in the spectrum of fermionic excitations. First, we excite the oscillations with a linear ramp of 1/a and study the evolution of |Δ|. Second, 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 Δgap.
2012
Scott, Robin George; Dalfovo, Franco; Pitaevskii, L. P.; Stringari, Sandro
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/96856
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 30
  • ???jsp.display-item.citation.isi??? 29
social impact