Quantum Institute: Visitor Schedule

The Quantum Lunch is regularly held on Thursdays in the Theoretical Division Conference Room, TA-3, Building 123, Room 121.
For more information, contact Diego Dalvit.

January 25, 2007
12:30 PM

Sergio Boixo,
CCS-3, LANL

Distinguished Quantum States

Abstract

Hilbert space is a big place. Therefore, it is often convenient, and illuminating, to define sets of distinguished quantum states: (generalized) coherent states, minimum uncertainty states, pointer states, decoherence free subspaces and noiseless subsystems. These different sets of states are defined in different ways, and for different reasons, but they are often intimately related.

In this talk, I will argue that minimum uncertainty states are best understood from the point of Fisher information. Their relation with generalized coherent states is well known. On the other hand, identifying generalized coherent states with pointer states requires, in general, a higher degree of symmetry than in the particular case of field coherent states. Finally, while the relation of all of the above with decoherence free subspaces is rather transparent, the relation with noiseless subsystems turns out to be somewhat more problematic.