1997/02/11 by Yu Shi, Shi, Yu
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Quantum Mechanics and Applications #Quantum, superfluid, helium dynamics #cond-mat #quant-ph
paper · pdf · doi:10.48550/arxiv.quant-ph/9702026
26 pages, Latex, a revised version
arxiv created 1997/03/22 · arxiv updated 2009/11/30
Spontaneous symmetry breaking originats in quantum mechanical measurement of the relevant observable defining the physical situation, order parameter is the average of this observable. A modification is made on the random-phase postulate validating the ensemble description. Off-diagonal long-range order, macroscopic wavefunction and interference effects in many-particle systems present when there is a so-called nucleation of quantum state, which is proposed to be the origin of spontaneous gauge symmetry breaking, for which nonconservation of particle number N is not essential. The approach based on nonvanishing expectation of the field operator, <ψ(r)>, is only a coherent-state approximation in thermodynamic limit. When N → ∞, this approach is equivalent, but <ψ(r)> is not the macroscopic wavefunction.