Quantum fluctuations in the superfluid state of the BCS-BEC crossover
By R. Diener, R. Sensarma, M. Randeria. 2007
149 citations recorded by the source corpus.
We determine the effects of quantum fluctuations about the T=0 mean-field solution of the BCS-BEC crossover in a dilute Fermi gas using the functional integral method. These fluctuations are described in terms of the zero-point motion of collective modes and the virtual scattering of gapped quasiparticles. We calculate their effects on various measurable properties, including chemical potential, ground-state energy, the gap, the speed of sound and the Landau critical velocity. At unitarity, we find excellent agreement with quantum Monte Carlo and experimental results. In the BCS limit, we show analytically that we obtain Fermi liquid interaction corrections to thermodynamics including the Hartree shift. In the Bose-Einstein condensation (BEC) limit, we show that the theory leads to an approximate description of the reduction of the scattering length for bosonic molecules and also obtain quantum depletion of the Lee-Yang form. At the end of the paper, we describe a method to include feedback of quantum fluctuations into the gap equation, and discuss the problems of self-consistent calculations in satisfying Goldstone's theorem and obtaining ultraviolet finite results at unitarity.
Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics
View Paper: https://www.semanticscholar.org/paper/3423032cb7dbdf7714f38c0c246e073f76f5442d
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In Atomic and Molecular Physics, and Optics
In Condensed Matter Physics
Citations in the corpus
- The BCS–BEC crossover: From ultra-cold Fermi gases to nuclear systems (2018, methodology): “From the theoretical side, emphasis was not given to the results obtained via functional-integral approaches [44, 45, 489] or quantum Monte Carlo methods [39, 38].”