## Application of Instatons: Quenching Of Macroscopic Quantum Coherence And Macroscopic Fermi-Particle Configurations

• Starting from the coherent state representation of the evolution operator with the help of the path-integral, we derive a formula for the low-lying levels E = ffl0 Gamma 24ffl cos(s + ,)ss of a quantum spin system. The quenching of macroscopic quantum coherence is understood as the vanishing of cos(s + ,)ss in disagreement with the suppression of tunneling (i.e. 4ffl = 0) as claimed in the literature. A new configuration called the macroscopic Fermi-particle is suggested by the character of its wave function. The tunne- ling rate ( 24fflss ) does not vanish, not for integer spin s nor for a half-integer value of s, and is calculated explicitly (for the position dependent mass) up to the one-loop approximation.

Author: H. J. W. Müller-Kirsten, Jiu-Qing Liang, Jian-Ge Zhou urn:nbn:de:hbz:386-kluedo-8588 Preprint English 1996 1996 Technische Universität Kaiserslautern 2000/04/03 Fachbereich Physik 5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik Standard gemäß KLUEDO-Leitlinien vor dem 27.05.2011

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