Fluctuations of the number of particles within a given volume in cold quantum gases
- Departament de Fisica i Enginyeria Nuclear, Campus Nord B4-B5, Universitat Politecnica de Catalunya, E-08034 Barcelona (Spain)
- Laboratoire de Physique Statistique, Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris Cedex 05 (France)
- Dipartimento di Fisica, Universita di Trento and BEC-INFM, I-38050 Povo, Italy and Kapitza Institute for Physical Problems, 119334 Moscow (Russian Federation)
In ultracold gases many experiments use atom imaging as a basic observable. The resulting image is averaged over a number of realizations and mostly only this average is used. Only recently the noise has been measured to extract physical information. In the present paper we investigate the quantum noise arising in these gases at zero temperature. We restrict ourselves to the homogeneous situation and study the fluctuations in particle number found within a given volume in the gas, and more specifically inside a sphere of radius R. We show that zero-temperature fluctuations are not extensive and the leading term scales with sphere radius R as R{sup 2} ln R (or ln R) in three- (or one-) dimensional systems. We calculate systematically the next term beyond this leading order. We consider first the generic case of a compressible superfluid. Then we investigate the whole Bose-Einstein-condensation (BEC) -BCS crossover, and in particular the limiting cases of the weakly interacting Bose gas and of the free Fermi gas.
- OSTI ID:
- 21140688
- Journal Information:
- Physical Review. A, Vol. 76, Issue 6; Other Information: DOI: 10.1103/PhysRevA.76.063616; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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