Canonical equivalence of quantum systems, multimode squeezed states and Robertson relation

1998/01/09 by D. A. Trifonov, Trifonov, D. A.
Physics and Astronomy · #FOS: Physical sciences #Quantum Physics (quant-ph) #quant-ph

paper · pdf · doi:10.48550/arxiv.quant-ph/9801015

19 pages, LaTex, no figures

arxiv created 1998/01/09 · arxiv updated 2009/12/01

Abstract

It is shown that any two Hamiltonians H(t) and H'(t) of N dimensional quantum systems can be related by means of time-dependent canonical transformations (CT). The dynamical symmetry group of system with Hamiltonian H(t) coincides with the invariance group of H(t). Quadratic Hamiltonians can be diagonalized by means of linear time-dependent CT. The diagonalization can be explicitly carried out in the case of stationary and some nonstationary quadratic H. Linear CT can diagonalize the uncertainty matrix σ(ρ) for canonical variables p_k, q_j in any state ρ, i.e., σ(ρ) is symplectically congruent to a diagonal uncertainty matrix. For multimode squeezed canonical coherent states (CCS) and squeezed Fock states with equal photon numbers in each mode σis symplectic itself. It is proved that the multimode Robertson uncertainty relation is minimized only in squeezed CCS.

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