Abstract The purpose of this article is to further investigate the assisted cloning of a d-dimensional arbitrary unknown state by utilizing quantum teleportation (QT) and remote state preparation (RST) techniques. We first propose a scheme for cloning an arbitrary unknown single-qudit state with assistance from a state preparer. In this scheme, the maximally and non-maximally bipartite d-dimensional states are used as quantum channels, respectively. In the first stage of scheme requires usual QT and in the second stage, the state preparer disentangles the left over entangled states by introducing one auxiliary qudit and performing a generalized CNOT, a single-qudit positive operator-valued measurement (POVM) and a single-qudit projective measurement process and conveys some classical messages to different parties so that a copy is produced probabilistically with the unit fidelity.Then by replacing the maximally or non-maximally bipartite d-dimensional entangled channel with a sequence of maximally or non-maximally bipartite d-dimensional entangled states as quantum channel, we can extend the above scheme to the case of cloning a d-dimensional arbitrary unknown m-qudit state with the unit fidelity and a certain probability in the help of the state preparer. PACS numbers 03.67.Hk, 03.67.-a, 03.65.Bz
Abstract The purpose of this article is to further investigate the assisted cloning of a d-dimensional arbitrary unknown state by utilizing quantum teleportation (QT) and remote state preparation (RST) techniques. We first propose a scheme for cloning an arbitrary unknown single-qudit state with assistance from a state preparer. In this scheme, the maximally and non-maximally bipartite d-dimensional states are used as quantum channels, respectively. In the first stage of scheme requires usual QT and in the second stage, the state preparer disentangles the left over entangled states by introducing one auxiliary qudit and performing a generalized CNOT, a single-qudit positive operator-valued measurement (POVM) and a single-qudit projective measurement process and conveys some classical messages to different parties so that a copy is produced probabilistically with the unit fidelity.Then by replacing the maximally or non-maximally bipartite d-dimensional entangled channel with a sequence of maximally or non-maximally bipartite d-dimensional entangled states as quantum channel, we can extend the above scheme to the case of cloning a d-dimensional arbitrary unknown m-qudit state with the unit fidelity and a certain probability in the help of the state preparer. PACS numbers 03.67.Hk, 03.67.-a, 03.65.Bz
By making use of d-dimensional Hadamard gates and d-dimensional controlled NOT gates, we first construct a five-qudit maximally entangled state, and then use it as the quantum channel to propose a new bidirectional scheme for cloning two different arbitrary unknown single-qudit simultaneously under the assistance from a state preparer and the control of a supervisor. This scheme consists of two stages: quantum teleportation and assisted cloning. To fulfil the purpose, the first stage of this scheme requires bidirectional controlled teleportation via our constructed five-qudit maximally entangled state as quantum channel, where two distant communicators can simultaneously exchange their unknown single-qudit states with unit fidelity and unit probability under the permission of the supervisor.In the second stage,the state preparer disentangles any remaining entangled states by introducing two auxiliary particles, implementing a unitary transformation and two single-particle projective measurements. Subsequently, they transmit a specific number of classical bits to two distinct communicators in order to generate two precise replicas of different unknown states. Subsequently, the above scheme is extended with a certain probability and unit fidelity by replacing the above d-dimensional quantum channel with a five-qudit non-maximally entangled state. Finally, we further analyze the expansion issues of our scheme from the perspectives of positive operator-valued measurement (POVM for short), general quantum channel and the number of state preparers and controllers, and point out that the scheme is secure.
We first propose a novel protocol to realize quantum cloning of an arbitrary unknown shared state with assistance offered by a state preparer. The initial phase of this protocol involves the utilization of quantum teleportation (QT), enabling the transfer of quantum information from an arbitrary number of senders to another arbitrary number of receivers through a maximally entangled GHZ-type state serving as a network channel, without centralizing the information at any specific location. In the second stage of this protocol, the state preparer performs a special single-qubit projective measurement and multiple Z-basis measurements and then communicates a number of classical bits corresponding to measurement results, the perfect copy or orthogonal-complementing copy of an unknown shared state can be produced at senders hands. Then, using a non-maximally entangled GHZ-type state instead of the aforementioned quantum channel, we extend the proposed protocol from three perspectives: projective measurement, positive operator-value measurement (POVM), and a single generalized Bell-state measurement. Our schemes can relay quantum information over a network without requiring fully trusted central or intermediate nodes, and none of participants can fully access the information.
In this paper, we propose a scheme that one can realize quantum cloning of an unknown multi-qudit state with assistance offered by a state preparer. Our scheme includes two parties: teleportation and assisted cloning. In order to complete the purpose, one multi-qudit state teleportation at the cloner's site via k entangled pairs as the quantum channel. After the teleportation, the state preparer Victor performs one unitary transformation and one multi-qudit measurement and informs Alice of his outcome to copy the original state. Compared with existing ones in the literature, our scheme generalize assisted cloning scheme to the case of arbitrary multi-qudit state, in the meantime, we also ensure high security of our scheme.
A protocol for cloning an arbitrary unknown two-qubit state and its orthogonal complement state with the assistance of a state preparer is presented. In this paper, a genuine four-particle entangled state which cannot be reduced to the product of two Bell states is used as the quantum channel. Moreover, positive operator-valued measure (POVM) instead of usual projective measurement is employed. In one hand, the usual teleportation is required. And in another hand, the perfect copies and complement copies of an unknown two-particle state can be implemented with a certain probability in the help of the state preparer.
Abstract We present two schemes for perfectly cloning an unknown single-qutrit equatorial state with assistance from two and N state preparers, respectively. In the first scheme, the sender wishes to teleport an unknown single-qutrit equatorial state from two state preparers to a remote receiver, and then to create a perfect copy of the unknown state at her location. The scheme consists of two stages. The first stage of the scheme requires the usual teleportation. In the second stage, to help the sender realize the quantum cloning, two state preparers perform single-qutrit projective measurements on their own qutrits from the sender, then the sender can acquire a perfect copy of the unknown state. It is shown that, only if the two state preparers collaborate with each other, the sender can create a copy of the unknown state by means of some appropriate unitary operations. In the second scheme, we generalized the jointly assisted cloning in the first scheme to the case of N state prepares. In the present schemes, the total probability of success for assisted cloning of a perfect copy of the unknown state can reach 1.
In this paper, two conclusive three-party cyclic assisted cloning protocols in amplitude damping (AD) channel are put forward that, respectively clone three arbitrary unknown single-qubit states and single-qutrit states with the help of a state preparer. Each of our protocols includes three consecutive stages: quantum channel preparation, cyclic quantum teleportation (CQT), and multi-party assisted cloning. The first stage of each protocol proposes the detailed processes of sharing a pure entangled quantum state as a component of a quantum channel in AD channel via entanglement compensation. In second stage, a three-party CQT is presented where three unknown single-qubit states (or single-qutrit states) are reconstructed simultaneously in three different places, respectively, by introducing auxiliary qubits and performing appropriate operations. In the third stage, the state preparer Victor performs one multi-qubit measurement (or one unitary transformation and one multi-qutrit measurement) and informs the three communicators of his outcome, three distinct unknown single-qubit states or their orthogonal complement states (or single-qutrit states) are cloned simultaneously and with probability at three separate locations,respectively. Furthermore, we extend the above protocols from two aspects: (i) the extension to the case of [Formula: see text] participants; (ii) extension to the case of d-dimensional unknown single-qudit state cycle-assisted cloning.