KTH/SU Mathematics Colloquium

2005-05-25

Michael Berry, Physics Department, Bristol University

Physics of nonhermitian degeneracies

Decoherence makes quantum evolution nonunitary, and such systems, where some freedoms are ignored, can be described by nonhermitian hamiltonian operators. These differ most dramatically from hermitian operators in the neighbourhood of degeneracies. Several examples of non-hermitian degeneracy-dominated physical phenomena will be given, in laser physics, atom optics, and crystal optics.