508 research outputs found
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 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
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