CLASSICAL COMMUNICATION COSTS IN QUANTUM INFORMATION PROCESSING

Classical communication plays an important role in quantum information processing such as remote state preparation and quantum teleportation. First, in this paper, we present some simple faithful remote state preparation of an arbitrary n-qubit state by constructing entanglement resources and special measurement basis for the sender. Then to weigh the classical resource required, we present an information-theoretical model to evaluate the classical communication cost. By optimizing the classical communication in quantum protocols, we obtain the optimal classical communication cost. This model can also be applied to the quantum teleportation. Moreover, based on the present computation model, we reinvestigate some remote state preparation and teleportation protocols in which the classical communication cost was imperfectly computed. Finally, some problems will be presented.

JOINT REMOTE PREPARATION OF A MULTI-QUBIT GHZ-CLASS STATE VIA BIPARTITE ENTANGLEMENTS

By joint actions of two separate two-qubit projective measurements, I present a new protocol for remotely preparing a two-qubit state via the shared three bipartite entanglements. The success probability and the classical communication cost are also minutely calculated. Then I concisely generalize it to multi-party case and multi-qubit state case, respectively. In contrast to the previous schemes [Int. J. Theor. Phys.48 (2009) 2005; Int. J. Theor. Phys.46 (2007) 2378; Commun. Theor. Phys.47 (2007) 247], this protocol has distinct advantages overwhelming the above ones as far as quantum resource consumption and quantum operation difficulty or intensity are concerned.

REMOTE PREPARATION OF TWO-QUBIT ENTANGLED STATE VIA ONE-DIMENSIONAL FOUR-QUBIT CLUSTER AND CLUSTER-CLASS STATES

We propose two protocols for remotely preparing a two-qubit entangled state, where the quantum channels take the form of one-dimensional four-qubit cluster and cluster-class states, respectively. The total success probability and classical communication cost are also calculated.

ENTANGLEMENT CONCENTRATION AND DILUTION REVISITED

In this paper, we revisit the entanglement concentration protocol of Bennett et al. and the entanglement dilution protocol of Lo and Popescu via the method of types and provide a simple upper bound on the coefficient of the [Formula: see text] bound on the classical communication cost of the Lo-Popescu protocol.

SCHEME FOR REMOTELY PREPARING THREE-PARTICLE GHZ-CLASS STATES

A scheme is proposed for remotely preparing a class of three-particle GHZ states by using a Bell state and a three-qubit GHZ state as the quantum channel. In the scheme, a two-qubit collective state measurement is performed and the necessary classical communication cost is 0.25 cbit on average. In general, the target state can be successfully prepared with the probability 1/4. However, if the state belongs to some special classes, the preparation success probability can reach 0.5 or even 1 after consuming a little additional classical resource. Comparing with the recent scheme [Opt. Commun.281, 871 (2008)], the present scheme has some advantages, e.g., the simpler quantum joint measurement and the less classical resource consumption.