BCS-BEC crossover-like phenomena driven by quantum-size effects in quasi-one-dimensional fermionic condensates
Abstract
Quantum confinement is known to influence fermionic condensates, resulting in quantum-size oscillations of superfluid/superconducting properties. Here we show that the impact of quantum-size effects is even more dramatic. Under realistic conditions, a significant phase-space reconfiguration induced by quantum-size effects opens a quasi-molecule channel in the fermionic pairing so that the condensed pairs exhibit features typical of a molecular state. As an illustration we consider a quasi-one-dimensional fermionic condensate, as realized, e.g., in cigar-shaped atomic Fermi gases or superconducting quantum wires. In this case the transverse quantization of the particle motion favors pairing through a coherent superposition of quantum channels that are formed due to the grouping of single-particle levels into a series of well distinguished subbands. Whenever the bottom of a subband approaches the Fermi level, the longitudinal spatial distribution of fermions in a condensed pair becomes strongly localized within the corresponding quantum channel. The fermionic pairs in this channel resemble molecules with bosonic character.
Cite
@article{arxiv.1110.4842,
title = {BCS-BEC crossover-like phenomena driven by quantum-size effects in quasi-one-dimensional fermionic condensates},
author = {A. A. Shanenko and M. D. Croitoru and A. V. Vagov and V. M. Axt and A. Perali and F. M. Peeters},
journal= {arXiv preprint arXiv:1110.4842},
year = {2011}
}