Xiaofeng Yin

Quantum operation sharing with symmetric and asymmetric W states

Two tripartite schemes for sharing a single-qubit operation on a remote target state are proposed with symmetric and asymmetric W states, respectively. They are treated and compared from the aspects of quantum resource consumption, operation complexity, classical resource consumption, success probability and efficiency. It is found that the first scheme is better than the second one. In particular, the sharing can be achieved probabilistically with the first scheme while deterministically with the second one.

MINIMAL CLASSICAL COMMUNICATION COST AND MEASUREMENT COMPLEXITY IN SPLITTING TWO-QUBIT QUANTUM INFORMATION VIA ASYMMETRIC W STATES

We propose a scheme for splitting a two-qubit quantum information by using two asymmetric W states as quantum channel. In this scheme the split state is assumed to be completely known by the sender. Because of this, during the splitting process, the sender only needs to perform a two-qubit projective measurement. Once the sender announces the measurement result in terms of the prior agreement, then using this message the two receivers can recover the quantum information via their mutual assistance. We calculate the success probability and classical communication cost of the scheme. In general, the splitting success probability (SSP) is 1/4 and the average classical communication cost is 0.25 bit. However, we find that for some states the SSP can reach 0.5 or even unity after consuming a little additional classical resource.

TRIPARTITION OF ARBITRARY SINGLE-QUBIT QUANTUM INFORMATION BY USING ASYMMETRIC FOUR-QUBIT W STATE

In this paper we propose a four-party scheme for a sender to achieve the tripartition of his/her arbitrary single-qubit quantum information among three recipients via an asymmetric four-qubit W state as quantum channels. In the scheme, if and only if, the three recipients cooperate together, they can perfectly retrieve the senders quantum information by performing first two 2-qubit collective unitary operations and then a single-qubit unitary operation. The scheme is symmetric with respect to the reconstruction for any recipient can conclusively recover the quantum information with the other twos helps.

A QUANTUM SPLITTING SCHEME OF ARBITRARY TWO-QUBIT STATE USING FOUR-QUBIT CLUSTER STATE

In this paper, we explore the channel capacity of the 4-qubit 4-term cluster state (i.e. (|0000〉 + |0011〉 + |1100〉 - |1111〉)/2) for splitting arbitrary two-qubit quantum information. After our extensive investigations, we found that 4 out of 12 possible distributions of the 4 qubits can be utilized to realize bipartite splitting. In terms of each distribution, the corresponding splitting scheme is presented and LOCCs (local operation and classical communication) are explicitly given.

Tripartite quantum operation sharing with two asymmetric three-qubit W states in five entanglement structures

Tripartite remote sharing of any single-qubit operation with two asymmetric three-qubit W states is amply treated. Five schemes are put forward with the W states in five different entanglement structures corresponding to five different distributions of two identical qubit trios in three locations. For all schemes, two features about the security and the agent symmetry are analyzed and confirmed. Moreover, resource consumption, necessary-operation complexity, success probability and efficiency are also worked out and compared mutually. For all schemes, quantum resource consumption and necessary-operation complexity are same. The last scheme needs to cost two additional classical bits than the former four schemes. Nonetheless, the last scheme is deterministic and has the highest efficiency in contrast to the other four probabilistic schemes with lower efficiencies. Through some analyses, it is found that both success probability and intrinsic efficiency of each scheme are completely determined by the corresponding entanglement structure of the two W states. The underlying physics of this feature is revealed. In addition, the implementation feasibility of all the schemes is analyzed and thus confirmed according to the current experimental techniques.

GENERALIZED THREE-PARTY QUBIT OPERATION SHARING

Two three-party schemes of qubit operation sharing proposed by Zhang and Cheung [J. Phys. B44 (2011) 165508] are generalized by utilizing partially entangled states as quantum channels instead of maximally entangled ones. Their quantum and classical resource consumptions, necessary-operation complexities, success probabilities and efficiencies are calculated and compared with each other. Moreover, it is revealed that the success probabilities are completely determined by the shared entanglement.

Shared quantum control via sharing operation on remote single qutrit

Two qubit-operation-sharing schemes (Zhang and Cheung in J. Phys. B 44:165508, 2011) are generalized to the qutrit ones. Operations to be shared are classified into three different classes in terms of different probabilities (i.e, 1/3, 2/3 and 1). For the latter two classes, ten and three restricted sets of operations are found out, respectively. Moreover, the two generalized schemes are amply compared from four aspects, namely, quantum and classical resource consumption, necessary-operation complexity, success probability and efficiency. It is found that the second scheme is overall more optimal than the first one as far as three restricted sets of operations are concerned. Moreover, the experimental feasibility of our schemes is confirmed with respect to the nowaday technique.

Analytic expression of quantum correlations in qutrit Werner states undergoing local and nonlocal unitary operations

Quantum correlations of a qutrit pair in Werner states undergoing local and nonlocal unitary operations are quantified in terms of two different methods, i.e., quantum discord (Ollivier and Zurek in Phys Rev Lett 88:017901, 2001) and measurement-induced disturbance (Luo in Phys Rev A 77:022301, 2008). Analytic expressions of the two kinds of quantum correlations in the system are worked on and found to be completely the same. By virtue of investigations and discussions, we expose some distinct features of the correlations and their underlying physics. More importantly, we found that both local and nonlocal unitary operations cannot increase quantum correlation in a qutrit Werner state for the two quantifiers which are concerned.

Preparation of genuinely entangled six-atom state via cavity quantum electrodynamics

A cavity quantum electrodynamics scheme for preparing a genuinely entangled state [A. Borras, et al., J. Phys. A 40 (2007) 13407] on six two-level atoms is proposed. In the scheme, the atom-cavity detuning is much bigger than the atom-cavity coupling strength and the necessary preparation time is much shorter than the Rydberg-atom lifespan. Hence the scheme has two distinct features, i.e., insensitive to the cavity decay and the atom radiation.

A NOTE ON "CHAIN TELEPORTATION WITH PARTIALLY ENTANGLED STATES"

The global chain teleportation protocol (GCTP) [Eur. Phys. J. D54 (2009) 111] is revisited via a three-node instantiation. The required operation ability and manipulation orderings of the three participants are sightly changed so that in the improved version, three additional important merits are resultant with consuming only an additional one-classical-bit message.