https://doi.org/10.1140/epjd/e2002-00234-8
Evolution of cat states in a dissipative parametric amplifier: decoherence and entanglement
1
Department of Mathematics and Computer Science, Faculty of Natural Science,
Suez Canal University, Ismailia, Egypt
2
Department of Optics (Joint Laboratory of Optics of Palacký University and
Institute of Physics, Academy of Sciences of the Czech Republic,
17. listopadu 50, 772 07 Olomouc, Czech Republic.) , Palacký University, 17. listopadu 50,
772 07 Olomouc, Czech Republic
3
Mathematics Department, College of Science, King Saud
University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
Corresponding author: a sebaweh@awalnet.net.sa
Received:
25
September
2001
Revised:
30
May
2002
Published online:
13
December
2002
The evolution of the Schrödinger-cat states in a dissipative parametric amplifier is examined. The main tool in the analysis is the normally ordered characteristic function. Squeezing, photon-number distribution and reduced factorial moments are discussed for the single- and compound-mode cases. Also the single-mode Wigner function is demonstrated. In addition to the decoherence resulting from the interaction with the environment (damped case) there are two sources which can cause such decoherence in the system even if it is completely isolated: these are the decay of the pump and the relative phases of the initial cat states. Furthermore, for the damped case there are two regimes, which are underdamped and overdamped. In the first (second) regime the signal mode or the idler mode “collapses" to a statistical mixture (thermal field).
PACS: 42.50.Dv – Nonclassical field states; squeezed, antibunched, and sub-Poissonian states; operational definitions of the phase of the field; phase measurements / 42.60.Gd – Q-switching
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2003