SU(2)-coherent states of the quantum systems

HUANG HONG-BIN, 东南大学物理系,南京,210018

It is shown, using the quasi-spin operator, that the BCS superconducting ground-state wave function is the direct product of single Cooper-pair SU(2) coherent state wave functions, and in certain conditions, is SU(2) coherent state wave function of the Cooper-pair system. If two superconductors, both in BCS ground state, are coupled together, the coupled system is also in SU(2) coherent state. Under the contraction of group SU(2) to harmonic-oscillator group, the SU(2) coherent states contract to Glauber coherent states. The quantum fluctuations, distributions, and second correlations of Cooper pairs and Josephson superfluidity in the two cases are discussed.

Masashi Ban

Barnana Roy, Pinaki Roy

HUANG HONG-BIN, 东南大学物理系,南京,210018

This paper introduces the generalized SU(2) coherent state of spin system. Its squee ing and antibunching, and generation are discussed. It is shown that under the contraction of group SU(2) to the harmonic-oscillator group, the generalized SU(2) coherent state transforms to the generalized Glauber coherent state, the related results of the contraction are also given.

M. Hongoh

Yu Wan‐Lun

Based on the group-theoretical structure for the density-dependent multi-photon Jaynes-Cummings model, the dressed SU(2) coherent state has been defined. The atom and field squeezing and the anti-bunching effect for the system evolved from the dressed SU(2) coherent state have been studied.