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

Year: 2012

Authors: Scott R.G., Dalfovo F., Pitaevskii L., Stringari S.

Autors Affiliation: INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, Via Sommarive 14, I-38123 Povo, Italy;
Kapitza Institute for Physical Problems, ulitsa Kosygina 2, 119334 Moscow, Russia.

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 vertical bar Delta vertical bar performs oscillations, which are sometimes called the \”Higgs\” mode, with the angular frequency 2 Delta(gap)/(h) over bar, where Delta(gap) 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 vertical bar Delta vertical bar. Second, we continously drive the system with a sinusoidal modulation of 1/a. In the first case, the oscillations in vertical bar Delta vertical bar 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 vertical bar Delta vertical bar. We propose two experimental protocols, based around the two approaches, to measure the frequency and damping of the oscillations, and hence Lambda(gap).


Volume: 86 (5)      Pages from: 053604  to: 053604

KeyWords: atomi ultrafreddi
DOI: 10.1103/PhysRevA.86.053604

Citations: 32
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