We investigate the quantum entropy, its power spectrum, and the excitation inversion of a Cooper pair box interacting with a nanomechanical resonator, the first initially prepared in its excited state, the second prepared in a “Schrödinger-cat” state. The method employs the...

We consider recent schemes [J.M. Liu, B. Weng, Physica A 367 (2006) 215] to teleport unknown atomic states and superposition of zero- and two-photon states using the two-photon Jaynes–Cummings model. Here we do the same using the “full two-photon Jaynes–Cumming”, valid for arbitrary...

We show that a recent proposal for the generation of displaced number states [G.C. de Oliveira et al., Physica A 351 (2005) 251] is misleading and cannot be implemented experimentally. We then discuss the possibility of creating highly excited displaced number states using standard procedures.

We propose preparation of a superposition of 2N circular squeezed states of stationary fields inside a high-Q cavity. Statistical properties of this state (photon number distribution, sub-Poissonian effect) and other nonclassical effects (squeezing, collapse–revival of the atomic inversion,...

A previous scheme [Physica A 280 (2003) 346] showed how to create a generalized superposition of two squeezed states for stationary fields and studied its statistical properties. Here we show how to extend this result for travelling fields.