No abstract

We examine several features of Bose-Einstein condensation (BEC)

When a single beam-splitter receives two beams of bosons described by Fock states (Bose-Einstein condensates at very low temperatures), interesting generalizations of the two-photon Hong-Ou-Mandel effect take place for larger number of particles. The distributions of particles at two detectors behind the beam splitter can be understood as resulting from the combination of two effects, the spontaneous phase appearing during quantum measurement, and the quantum angle. The latter introduces quantum "population oscillations", which can be seen as a generalized Hong-Ou-Mandel effect, although they do not always correspond to even-odd oscillations.Keywords Quantum mechanics · Bose-Einstein condensates · Quantum optics · Hong-Ou-Mandel effect · Beam splitter Beam splitters are an essential component of many experiments designed to observe quantum effects. They are involved in experimental and theoretical schemes that both Helmut Rauch and Daniel Greenberger have studied. Indeed, the famous neutron experiments of H. Rauch and colleagues [1, 2] were made possible by the realization of an appropriate device allowing neutron beams to be split into two coherent beams, which can then be recombined and give rise to various interesting quantum interference effects. The observation of equally famous quantum GHZ (Greenberger, Horne and Zeilinger) violations of local realism [3,4] may also require the use of photon F. Laloë ( ) Laboratoire Kastler Brossel, ENS,

We have corrected a temperature calibration error caused by a change in instrumentation. The temperature correction for the solid helium temperature is less than 1 mk above 120 mK, 5.5 mK at 80 mK, and can be found from TC new ¼ TC − 0.09637 expð−TC=0.02755Þ. Temperatures reported in a longer detailed manuscript now in preparation will include the calibration correction. No significant conclusions are changed by this correction. The original most relevant text that needs to be modified is part of the paragraph that begins at the end of the right column on page 3 of the text. The replacement corrected text reads as follows: A fit of the data by χ ¼ expð−R=TÞ yields R ¼ 1.11 K. A model that includes a small number of binding sites for 3 He or 4 He atoms yields the functional form χ ¼ expða − R=TÞ, where expðaÞ=½1 þ expðaÞ is the minimum concentration that blocks superflow, and R includes the binding energy. With this functional form, we find a much better fit, with R ¼ 1.32 K and a ¼ 2.18.

Spin d~namics for arbitrarily polarized and very dilute solutions of 3He in liquid He are described. We began at a very fundamental level by deriving a kinetic equation for arbitrarily polarized dilute quantum systems based on a method due to Boercker and Dufty. This approach allows more controlled approximations than our previous derivation based on the Kadanoff-Baym technique. Our previous work is here generalized to include T-matrix interactions rather than the Born approximation. Spin hydrodynamic equations are derived. The general equations are valid for both Fermi and Bose systems. By use of a well-known phenomenological potential to describe the 3He-JHe Tmatrix we calculate longitudinal and transverse spin diffusion coefficients D_L and D/I and the identical-particle spin-rotation parameter ~t. We confirm that these two diffusion constants differ at low T with DI approaching a constant as T ~ O, and D H ~ lIT 2. Estimates of errors made by our approximations are considered in detail. Good agreement is found in comparison with data from both Cornell University and the University of Massachusetts. We find that the s-wave approximation is inadequate and that mean-field corrections are important. Comparison is also made between theory and the recent UMass viscosity measurements.