TY  - RPRT
TI  - Off-diagonal geometric phase for mixed states.
AU  - Stefan Filipp
AU  - Erik Sjöqvist
PY  - 2003
DO  - 10.1103/physrevlett.90.050403
UR  - https://pubmed.ncbi.nlm.nih.gov/12633343/
ID  - 12633343
ER  -