Guo-Jian Yang

Controlled teleportation against uncooperation of part of supervisors

We study the teleportation of an unknown quantum state from a sender (Alice) to a receiver (Bob) via the control of many supervisors (Charlie 1, Charlie 2, . . .) in a network. It has been shown that such a task can be achieved by distributing a GHZ-type entangled state among the participants in advance. In the protocols with GHZ-type entanglement channel, the achievement of teleportation between Alice and Bob is conditioned on the cooperation of all the supervisors. In other words, if anyone of the supervisors does not cooperate, the teleportation will fails. In this paper, we introduce another kind of controlled teleportaton protocol with other types of entangled states acting as the quantum channel, in which the teleportation between Alice and Bob can be realized with high degree of endurance against uncooperation of part of supervisors.

Remote information concentration and multipartite entanglement in multilevel systems

Remote information concentration (RIC) in

Simple schemes for quantum information processing with W-type entanglement

d

Controlling the signal-to-noise ratio in optical parametric image amplification

-level systems (qudits) is studied. It is shown that the quantum information initially distributed in three spatially separated qudits can be remotely and deterministically concentrated to a single qudit via an entangled channel without performing any global operations. The entangled channel can be different types of genuine multipartite pure entangled states which are inequivalent under local operations and classical communication. The entangled channel can also be a mixed entangled state, even a bound entangled state which has a similar form to the Smolin state, but has different features from the Smolin state. A common feature of all these pure and mixed entangled states is found; i.e., they have

Sensitized intense near-infrared downconversion quantum cutting three-photon luminescence phenomena of the Tm(3+) ion activator in Tm(3+)Bi(3+):YNbO(4) powder phosphor.

{d}^{2}

Multiphoton near-infrared quantum cutting luminescence phenomena of Tm 3+ ion in (Y 1-x Tm x ) 3 Al 5 O 12 powder phosphor

common commuting stabilizers. The differences of qudit-RIC and qubit-RIC (

Generalized phase states and dynamics of generalized coherent states

d=2

Stopping and storing a light pulse in an ultracold atomic medium

) are also analyzed.

Near Infrared Quantum Cutting Luminescence of Er 3+ /Tm 3+ Ion Pairs in a Telluride Glass

Simple schemes are proposed for implementing deterministic teleportation, superdense coding, and quantum information splitting with W-type entangled states. The physical realization of these schemes should be much simpler than previous ones due to the assistance of an auxiliary particle. We illustrate the ideas in cavity quantum electrodynamics. The important features of our schemes can also be demonstrated in other systems.

Compact quantum gates for hybrid photon---atom systems assisted by Faraday rotation

We analyse a scheme for phase-sensitive amplification of an optical image without using Fourier-transforming lenses, as carried out in a recent experiment. Our analysis shows that the scheme works well with a broadband amplifier, which ensures that the output image is a faithful copy of the object. In addition, when the area of the pixel detector is close to the minimum imaging resolution, both a large output signal-to-noise ratio and noiseless amplification can be realized.