Quantum gates with "hot" trapped ions

We propose a scheme to perform a fundamental two-qubit gate between two trapped ions using ideas from atom interferometry. As opposed to the scheme considered by J. I. Cirac and P. Zoller, Phys. Rev. Lett. 74, 4091 (1995), it does not require laser cooling to the motional ground state.Comment: 4 pages, 2 eps figure

Complete Characterization of a Quantum Process: the Two-Bit Quantum Gate

We show how to fully characterize a quantum process in an open quantum system. We particularize the procedure to the case of a universal two-qubit gate in a quantum computer. We illustrate the method with a numerical simulation of a quantum gate in the ion trap quantum computer.Comment: Accepted for publication in Physical Review Letters 08Nov96 (submitted 15Jly96

Distinguishing n Hamiltonians on C^n by a single measurement

If an experimentalist wants to decide which one of n possible Hamiltonians acting on an n dimensional Hilbert space is present, he can conjugate the time evolution by an appropriate sequence of known unitary transformations in such a way that the different Hamiltonians result in mutual orthogonal final states. We present a general scheme providing such a sequence.Comment: 4 pages, Revte

A quantum phase gate implementation for trapped ions in thermal motion

We propose a novel scheme to implement a quantum controlled phase gate for trapped ions in thermal motion with one standing wave laser pulse. Instead of applying the rotating wave approximation this scheme makes use of the counter-rotating terms of operators. We also demonstrate that the same scheme can be used to generate maximally entangled states of $N$ trapped ions by a single laser pulse

Avulsión del tubérculo tibial asociada a epifisiólisis proximal de tibia

Las lesiones de la tuberosidad tibial anterior son fracturas poco frecuentes que se presentan generalmente en adolescentes. Su extensión fisaria hacia la cortical posterior constituye un hecho infrecuente. Algunos autores consideran necesaria la modificación de la clasifícacion de Watson-Jones añadiéndole un tipo IV. Se presenta un caso de epifisiólisis proximal de tibia asociada a avulsión del tubérculo tibial, se discute dicha clasificación, el mecanismo de producción y revisión de la literaturaFractures of the anterior tibial tubercle are uncommon lesions, adolescents being more frequently affected. Physeal extension through the posterior tibial cortical bone is rare. Some authors have suggested that a new type IV can be added to the Watson-Jones classiflcation. In this paper, we report a case with epiphysiolisis of the proximal tibia associated to an avulsion fracture of the anterior tibial tubercle. The Watson-Jones classiflcation, the mechanism of injury are discussed together a review of the literature

Observable geometric phase induced by a cyclically evolving dissipative process

In a prevous paper (Phys. Rev. Lett. 96, 150403 (2006)) we have proposed a new way to generate an observable geometric phase on a quantum system by means of a completely incoherent phenomenon. The basic idea was to force the ground state of the system to evolve ciclically by "adiabatically" manipulating the environment with which it interacts. The specific scheme we have previously analyzed, consisting of a multilevel atom interacting with a broad-band squeezed vacuum bosonic bath whose squeezing parameters are smoothly changed in time along a closed loop, is here solved in a more direct way. This new solution emphasizes how the geometric phase on the ground state of the system is indeed due to a purely incoherent dynamicsComment: 6 pages, 1 figur

Prensado, con métodos de la cerámica plana, de piezas cerámicas curvas con especificaciones geométricas de elevada precisión

In order to obtain high-precision three-dimensional pieces by dry pressing, two approaches were studied: modelling the material flow and strain during pressing; and evaluating the bulk density (Da) distribution in a pressed piece and using shrinkage models that allow the post-firing geometry to be predicted. It would thus become possible to act in the design phase (functional geometry and rear) and in the process. This paper describes the studies carried out to predict the final geometry of three-dimensional pieces of the sheet type obtained by conventional pressing techniques, from the Da distribution in each point of the piece. For this purpose, pieces were modelled using finite element method (FEM), applying simulation processes to obtain the strain at each point of the piece as a function of its Da. The experimental validation was performed using the X-ray absorption method for Da and a CMM (coordinate measuring machine) for the geometr

Reactivity of 2-acetylhydrazonemethyl-l -arylimidazole with reducing agents

La hidrogenación catalítica de los compuestos 1 origina mayoritariamente el producto resultante de la hidrogenolisis del enlace C=N y sólo se obtienen bajos rendimientos de las hidracidas 2 al utilizar Pd(C) como catalizador. La reducción con AILiH4 de la rinde, para el estereoisómero Z, la hidracida 2a; mientras que el estereoisómero E conduce por hidrogenolisis a los compuestos 4a y 5a.Catalytic hydrogenation of compounds 1 led mainly to the products resulting of the hydrogenolysis of the bond C=N, while the hydrazides 2 were obtained in small yields using Pd(C) as catalyst. Reduction of la with AILiH. yielded the hydrazide 2a for the Z stereoisomer and the products 4a and 5a for the E stereoisomer by hydrogenolysis

A Stochastic Liouville Equation Approach for the Effect of Noise in Quantum Computations

We propose a model based on a generalized effective Hamiltonian for studying the effect of noise in quantum computations. The system-environment interactions are taken into account by including stochastic fluctuating terms in the system Hamiltonian. Treating these fluctuations as Gaussian Markov processes with zero mean and delta function correlation times, we derive an exact equation of motion describing the dissipative dynamics for a system of n qubits. We then apply this model to study the effect of noise on the quantum teleportation and a generic quantum controlled-NOT (CNOT) gate. For the quantum CNOT gate, we study the effect of noise on a set of one- and two-qubit quantum gates, and show that the results can be assembled together to investigate the quality of a quantum CNOT gate operation. We compute the averaged gate fidelity and gate purity for the quantum CNOT gate, and investigate phase, bit-flip, and flip-flop errors during the CNOT gate operation. The effects of direct inter-qubit coupling and fluctuations on the control fields are also studied. We discuss the limitations and possible extensions of this model. In sum, we demonstrate a simple model that enables us to investigate the effect of noise in arbitrary quantum circuits under realistic device conditions.Comment: 36 pages, 6 figures; to be submitted to Phys. Rev.

Reactividad de 2-acetilhidrazonometil-1-arilimidazol frente a agentes reductores

Catalytic hydrogenation of compounds 1 led mainly to the products resulting of the hydrogenolysis of the bond C=N, while the hydrazides 2 were obtained in small yields using Pd(C) as catalyst. Reduction of la with AlLiH4 yielded the hydrazide 2a for the Z stereoisomer and the products 4a and 5a for the E stereoisomer by hydrogenolysis.La hidrogenación catalítica de los compuestos 1 origina mayoritariamente el producto resultante de la hidrogenolisis del enlace C=N y sólo se obtienen bajos rendimientos de las hidracidas 2 al utilizar Pd(C) como catalizador. La reducción con AlLiH4 de la rinde, para el estereoisómero Z, la hidracida 2a; mientras que el estereoisómero E conduce por hidrogenolisis a los compuestos 4a y 5a