[OPTICAL REVIEW Vol. 6, No. 3 (1999) 227-231]

Quantum Phase Dynamics of Interaction between Photon Field and Magnetic System: Effects of Magnetic Quantum Tunnelling*

Hidemi NAGAO, Masayoshi NAKANO, Yasuteru SHIGETA and Kizashi YAMAGUCHI

Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043 Japan

(Received December 7, 1998; Accepted December 28, 1998)

We investigate the dynamics of probability distributions of an initially one-mode coherent field interacting with a four-state molecular system, which is a single magnet with a tunneling across an anisotropic barrier, using a numerically exact approach. The population for each state, the phase properties of <cos2ψ^> and Δ cos2 ψ(≡<cos2ψ^>−<cos ψ^>2), and the entropy are calculated for a model system. The model predicts that the molecule and field become asymptotically disentangled at half of the revival time, and that optical Schrödinger-cat and magnetic Schrödinger-cat states are generated.

Key words : quantum phase dynamics, magnetic quantum tunnelling, collapse and rivival, phase properties, Jaynes-Cummings model