We propose a method for analyzing Berry phase for a multi-qubit system of superconducting charge qubits interacting with a microwave field. By suitably choosing the system parameters and precisely controlling the dynamics, novel connection found between the Berry phase and entanglement creations. إقراء المزيد

We propose a method to control the atomic dynamics in the presence of electromagnetic fields. Instead of measuring the population dynamics, we focus on the possibility of controlling the Pancharatnam phase. For a two-level system we find that this phase can be optically induced and controlled by the phase shift. More importantly, the nonlinear interaction between the atom and the ... إقراء المزيد

Considering ultracold atoms traversing a high-Q Fabry-Pérot cavity, we theoretically demonstrate a quantum nondemolition measurement of the photon number. This fully quantum mechanical approach may be understood utilizing concepts as effective mass and group velocity of the atom. The various photon numbers induce a splitting of the atomic wave packet, and a time-of-flight measurement of the atom thereby reveals the ... إقراء المزيد

This contribution describes some new features of quantum entanglement in a single three-level trapped ion confined in a two-dimensional (2D) harmonic potential. The dynamical properties of quantum entanglement are studied in terms of the reduced-density linear entropy considering two specific initial states of the field. Allowing the instantaneous position of the centre-of-mass motion of the ion to be explicitly time ... إقراء المزيد

In a recent paper Dajka, et.al., [J. Phys. A \textbf{40}, F879 (2007)] predicted that some composite systems can be entangled forever even if coupled with a thermal bath. We analyze the transient entanglement of a single-Cooper-pair box biased by a classical voltage and irradiated by a quantized field and find the unusual feature that the phase-damped cavity can lead to ... إقراء المزيد

We explore and develop the mathematics of the two multi-level ions. In particular, we describe some new features of quantum entanglement in two three-level trapped ions confined in a one-dimensional harmonic potential, allowing the instantaneous position of the center-of-mass motion of the ions to be explicitly time-dependent. By solving the exact dynamics of the system, we show how survivability of ... إقراء المزيد

We analyze a controllable generation of maximally entangled mixed states of a circuit containing two-coupled superconducting charge qubits. Each qubit is based on a Cooper pair box connected to a reservoir electrode through a Josephson junction. Illustrative variational calculations were performed to demonstrate the effect on the two-qubits entanglement. At sufficiently deviation between the Josephson energies of the qubits and/or ... إقراء المزيد

The speed of quantum computation is investigated through the time evolution of the speed of the orthogonality. The external field components for classical treatment besides the detuning and the coupling parameters for quantum treatment play important roles on the computational speed. It has been shown that the number of photons has no significant effect on the speed of computation. However, ... إقراء المزيد

This article provides a convenient framework for a quantitative evaluation of the transient entropy squeezing generated when a single-Cooper-pair box irradiated by a classical field taking into account a phase-damped cavity. It explores how the entropy squeezing factors influenced by phase-damped cavity. The numerical results reveal an interesting connection between entropy squeezing and entanglement dynamics. إقراء المزيد

We construct a complete representation of the atomic information entropy of an arbitrary multi-level system. Our approach is applicable to all scenarios in which the quantum state shared by a single particle and fields is known. As illustrations we apply our findings to a single four-level atom strongly coupled to a cavity field and driven by a coherent laser field. ... إقراء المزيد