tailieunhanh - New deterministic protocol for joint remote preparation of two-qubit states

Designing quantum protocols with unit success probability is highly desirable from a viewpoint of . In this work, we propose a new deterministic protocol for joint remote preparation of the most general two-qubit state using the same quantum/classical resource as in [An et al., Phys. Lett. | Communications in Physics, Vol. 22, No. 3 (2012), pp. 193-200 NEW DETERMINISTIC PROTOCOL FOR JOINT REMOTE PREPARATION OF TWO-QUBIT STATES NUNG VAN DON, CAO THI BICH, NGUYEN BA AN Center for Theoretical Physics, Institute of Physics, VAST Abstract. Designing quantum protocols with unit success probability is highly desirable from a viewpoint of the overall resource cost. In this work, we propose a new deterministic protocol for joint remote preparation of the most general two-qubit state using the same quantum/classical resource as in [An et al., Phys. Lett. A 375 (2011) 3570] and, at the same time, retaining the passive role of the receiver as in [Xiao et al., J. Phys. B: At. Mol. Opt. Phys. 44 (2011) 075501], which employs a different kind of nonlocal resource. From a practical point of view, this protocol proves most suitable in situations when only Einstein- Podelsky-Rosen pairs are supplied and the receiver is not capable of performing any measurements nor controlled-NOT gates. I. INTRODUCTION Absolutely different from classical communication, in quantum communication information is encoded in qubits [1] which may be in terms of superposed multiqubit states. Security of communication is provided by fundamental laws of nature according to which the qubits cannot be cloned [2] nor learned without traces left behind. Yet, sending informative qubits themselves through space is not a good idea, since the arrived information may be unfaithful due to tampering en route of unauthorized parties. In 1993 a milestone quantum protocol [3] was designed enabling one to teleport a unknown qubit securely and faithfully by means of local operation and classical communication (LOCC). This appears possible thanks to a special kind of resource named entanglement [4] which must a priori be shared between the communicating parties. In case the state is known, its transmission can be done simpler by what is called remote state preparation (RSP) [5], using the same shared amount of