Comparison between decoherence time for a two-state spin ½ system with its corresponding quantum retrieval period

The evolution of a two-state quantum system (a spin ½ particle) in both the framework of standard quantum mechanics and under the decoherence regime is considered. The former approach on this issue is the well-known quantum flipping process of a dichotomic system subjected to a time-dependent magnetic field. In the latter approach, the Spin-Boson model is utilized to describe the interaction of system with its environment and the Born-Markov master equation is derived to obtain the decoherence time. It is possible to show that under certain conditions, one may find a potential conflict between the predictions of decoherence theory and the result observed in a typical quantum flipping experiment.

ATOM-OPTICAL BISTABILITY IN TRAPPED BOSE–EINSTEIN CONDENSATES

The close similarities between nonlinear optics and nonlinear atom optics motivate us to demonstrate the possibility of atom-optical bistability for a trapped Bose–Einstein condensate. Driven by an intense, coherent input matter wave, the trapped Bose–Einstein condensate might display the bistability when the Born–Markov master equation for the condensate mode is used. The atom-optical bistability provides a way to control atom lasers with atom lasers.

Absorptive Quantum Measurements via Coherently Coupled Quantum Dots

We propose an absorptive measurement scheme via coupled quantum dots based on studies of the quantum dynamics of coherently coupled dots. The system is described through a Markov master equation that is related to a measurable quantity, the current. We analyse the measurement configuration and calculate the correlations and noise spectra beyond the adiabatic approximation.