22 research outputs found
Quantum information transfer for qutrits
We propose a scheme for the transfer of quantum information among distant
qutrits. We apply this scheme to the distribution of entanglement among distant
nodes and to the generation of multipartite antisymmetric states. We also
discuss applications to quantum secret sharing
Detuning effects in the one-photon mazer
The quantum theory of the mazer in the non-resonant case (a detuning between
the cavity mode and the atomic transition frequencies is present) is written.
The generalization from the resonant case is far from being direct. Interesting
effects of the mazer physics are pointed out. In particular, it is shown that
the cavity may slow down or speed up the atoms according to the sign of the
detuning and that the induced emission process may be completely blocked by use
of a positive detuning. It is also shown that the detuning adds a potential
step effect not present at resonance and that the use of positive detunings
defines a well-controlled cooling mechanism. In the special case of a mesa
cavity mode function, generalized expressions for the reflection and
transmission coefficients have been obtained. The general properties of the
induced emission probability are finally discussed in the hot, intermediate and
cold atom regimes. Comparison with the resonant case is given.Comment: 9 pages, 8 figure
Entangled coherent states under dissipation
We study the evolution of entangled coherent states of the two quantized
electromagnetic fields under dissipation. Characteristic time scales for the
decay of the negativity are found in the case of large values of the phase
space distance among the states of each mode. We also study how the
entanglement emerges among the reservoirs.Comment: 13 pages and 4 figures, published versio
Quantitative Treatment of Decoherence
We outline different approaches to define and quantify decoherence. We argue
that a measure based on a properly defined norm of deviation of the density
matrix is appropriate for quantifying decoherence in quantum registers. For a
semiconductor double quantum dot qubit, evaluation of this measure is reviewed.
For a general class of decoherence processes, including those occurring in
semiconductor qubits, we argue that this measure is additive: It scales
linearly with the number of qubits.Comment: Revised version, 26 pages, in LaTeX, 3 EPS figure
Percepción al cambio climático y a la gestión del agua: aportes de las estrategias metodológicas cualitativas para su comprensión
Equivalence between macroscopic quantum superpositions and maximally entangled states: Application to phase-shift detection
Qutrit quantum computer with trapped ions
The physical implementation of a qutrit quantum computer in the context of trapped ions was studied. A universal two-qutrit gate which corresponded to a controlled-NOT gate between qutrits was considered. It was found that using this gate and a general gate of an individual qutrit, any gate can be decomposed into a sequence of these gates
An algebraic approach to the Jaynes-Cummings model with dissipation
An alternative approach for the Jaynes-Cummings model with dissipation is presented. An analytic solution of the master equation is obtained in the strong field regime. The extension to other models is discussed
Macroscopic field superpositions from collective interactions
We study the generation of both coherent superpositions and mixtures of field states through the interaction of an initially coherent field state with a collection of two-level atoms. The proposed scheme to build up a given superposition is based on effective dispersive interactions which arise from both the large detuning limit and the strong-field limit. The coherent superposition is obtained by interacting with a classical field after the cluster leaves the cavity followed by a measurement of the atomic population