TY  - RPRT
TI  - Quantum-noise matrix for multimode systems: U(n) invariance, squeezing, and normal forms.
AU  - R Simon
AU  - N Mukunda
AU  - B Dutta
PY  - 1994
DO  - 10.1103/physreva.49.1567
UR  - https://pubmed.ncbi.nlm.nih.gov/9910403/
ID  - 9910403
ER  -