Scheme for Cloning an Unknown Entangled State with Assistance via Non-maximally Entangled Cluster States

We present two schemes for perfect cloning unknown two-qubit and general twoqubit entangled states with assistance from two state preparers, respectively. In the schemes, the sender wish to teleport an unknown two-qubit (or general two-qubit) entangled state which from two state preparers to a remote receiver, and then create a perfect copy of the unknown state at her place. The schemes include two stages. The first stage of the schemes requires usual teleportation. In the second stage, to help the sender realize the quantum cloning, two state preparers perform two-qubit projective measurements on their own qubits which from the sender, then the sender can acquire a perfect copy of the unknown state. To complete the assisted cloning schemes, several novel sets of mutually orthogonal basis vectors are introduced. It is shown that, only if two state preparers collaborate with each other, and perform projective measurements under suitable measuring basis on their own qubit respectively, the sender can create a copy of the unknown state by means of some appropriate unitary operations. The advantage of the present schemes is that the total success probability for assisted cloning a perfect copy of the unknown state can reach 1.Keywords Assisted cloning · Teleportation · Two-qubit entangled state · General two-qubit entangled state · Two-qubit projective measurement IntroductionEntanglement is the most fascinating feature of quantum mechanics and plays a central role in quantum information processing such as quantum teleportation [1], quantum dense coding [2], quantum cryptography [3], quantum secret sharing [4], and so on. Entanglement is also related to quantum cloning. Different from classical information, an unknown quantum state cannot be cloned exactly because of the on-cloning theorem [5]. However, quantum

Section: Assisted Cloning Of An Unknown General Two-qubit Entangled Smentioning

confidence: 86%

Section: Assisted Cloning Of An Unknown General Two-qubit Entangled Smentioning

confidence: 99%

See 1 more Smart Citation

Deterministic Joint Assisted Cloning of Unknown Two-Qubit Entangled States

Zhan

2011

“…We also notice that there had some proposals in attempting to realize the assisted cloning for a two-qubit pure state [31][32][33]. Nevertheless it should be pointed out that in Refs.…”

mentioning

confidence: 88%

Assisted Cloning and Orthogonal Complementing of an Arbitrary Two-qubit State

Xiao

Liu

2011

We propose a scheme to create a perfect copy or a complement copy of an arbitrary bipartite state with assistance from a state preparer. The scheme contains a two-qubit state teleportation from a sender to a receiver by using two partially entangled pairs as quantum channel. After the teleportation, to help the sender to clone the initial state, the state preparer performs an appropriate bipartite projective measurement and informs the sender of the measurement result. It is found that the exact copying and complementing of the arbitrary two-qubit state can be produced probabilistically with unity fidelity, and the success probability of perfect cloning will peak to 1 if the original state is chosen from some special ensembles.Keywords Quantum cloning · Quantum teleportation · Two-qubit state · Bi-particle projective measurementThe no-cloning theorem, which is proved by Wootters and Zurek [1] and Dieks [2], forbids the creation of identical copies of an arbitrary unknown quantum state, and thus ensures the security of quantum information processing known as quantum key distribution [3][4][5], quantum cryptography [6], quantum dense coding [7], quantum teleportation [8], and so on. It gives rise to a contrary question at the same time that is how to replicate information in quantum information field which is necessary to some extent and is very easy to realize in classical counterpart. In 1996, Buzek and Hillery proposed the concept of quantum cloning machine [9] and proved that the approximate cloning for an arbitrary unknown quantum state is realizable. Afterwards, the authors of Refs. [10,11] presented the protocols X.-Q. Xiao ( )

“…The perfect copies and orthogonal-complement copies of an unknown state can be produced. Inspired by Pati's original paper, a lot of schemes for assisted cloning have been proposed [11][12][13][14][15][16][17][18][19][20][21][22][23]. Among them, some protocols concentrated on the clone of an unknown N(≥ 3)-qubit entangled state…”

Section: Introductionmentioning

confidence: 99%

Deterministic Clone of an Unknown N-Qubit Entangled State with Assistance

Chen

Guan

et al. 2010

We propose a deterministic scheme to realize assisted-clone of an unknown N(≥ 3)-qubit entangled state. The first stage of the protocol requires teleportation via maximal entanglement as the quantum channel. In the second stage of the protocol, a novel set of mutually orthogonal basis vectors are constructed. With the assistance of the preparer through an N -particle projective measurement under this basis, the perfect copy of an original state can be produced. Comparing with the previous protocols which produce the unknown state and its orthogonal complement state at the site of the sender, our scheme generates the unknown state deterministically.