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.