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Quantum cloning of identical mixed qubits [article]

H.Fan, B.Y.Liu, K.J.Shi
2007 arXiv   pre-print
This quantum cloning machine is optimal in the sense that the shrinking factor between the input and the output single qubit achieves the upper bound.  ...  We propose the quantum cloning transformations not only for the triplet (symmetric) states but also for the singlet (antisymmetric) state.  ...  This quantum cloning machine is optimal in the sense the shrinking factor between single input and output qubit achieves the upper bound which is the same as for the pure qubit.  ... 
arXiv:quant-ph/0601017v4 fatcat:tpnnwrcrvrfklnjvpnteiklcka

Joint measurements on qubits and cloning of observables [article]

Alessandro Ferraro, Matteo G A Paris
2007 arXiv   pre-print
We see that, even if the cloning machine is designed to act on the whole class generated by two noncommuting observables, the same optimal performances of a joint measurement can be attained.  ...  This helps in establishing an optimality criterion for cloning of observables.  ...  Acknowledgments This work has been supported by MIUR through the project PRIN-2005024254-002.  ... 
arXiv:quant-ph/0701089v1 fatcat:vpuhkfcvujgupp2khdpmqfdj2a

Minimal input sets determining phase-covariant and universal quantum cloning

Li Jing, Yi-Nan Wang, Han-Duo Shi, Liang-Zhu Mu, Heng Fan
2012 Physical Review A. Atomic, Molecular, and Optical Physics  
This can simplify dramatically the testing of whether the quantum clone machines are successful or not, we only need to check that the minimal input sets can be cloned optimally.  ...  The phase-covariant quantum cloning machine, which can copy all qubits located on the equator of the Bloch sphere, can be determined by three equatorial qubits with equal angular distance.  ...  In the past years, different schemes of quantum cloning are proposed, and various quantum cloning machines are designed for different tasks [2] [3] [4] [5] .  ... 
doi:10.1103/physreva.86.062315 fatcat:hhbbybhmwrewbf4sv63zjn6plq

Optical realization of universal quantum cloning

Yun-Feng Huang, Wan-Li Li, Chuan-Feng Li, Yong-Sheng Zhang, Yun-Kun Jiang, Guang-Can Guo
2001 Physical Review A. Atomic, Molecular, and Optical Physics  
Beyond the no-cloning theorem, the universal symmetric quantum cloning machine was first addressed by Buzek and Hillery.  ...  We showed that, the fidelities between the two output qubits and the original qubit are both 5/6 (which proved to be the optimal fidelity of one-to-two qubits universal cloner) for arbitrary input pure  ...  Acknowledgment This work was supported by the National Natural Science Foundation of China.  ... 
doi:10.1103/physreva.64.012315 fatcat:feaw5nc4dvcudfvpkt66ku7uou

Joint Measurements on Qubits and Cloning of Observables

Alessandro Ferraro, Matteo G. A. Paris
2007 Open systems & information dynamics  
We see that, even if the cloning machine is designed to act on the whole class generated by two noncommuting observables, the same optimal performances of a joint measurement can be attained.  ...  This helps in establishing an optimality criterion for cloning of observables.  ...  Acknowledgments This work has been supported by MIUR through the project PRIN-2005024254-002.  ... 
doi:10.1007/s11080-007-9043-5 fatcat:ac63tkgbp5hprmfj7xcoi7lqq4

Universal optimal cloning of qubits and quantum registers [article]

Vladimir Buzek and Mark Hillery (Institute of Physics, SAS, Bratislava, Slovakia & Department of Physics and Astronomy, Hunter College, CUNY, New York, USA)
1998 arXiv   pre-print
We also present network for an optimal quantum copying "machine" (transformation) which produces N+1 identical copies from the original qubit.  ...  We review our recent work on the universal (i.e. input state independent) optimal quantum copying (cloning) of qubits.  ...  CONCLUSIONS We have presented the universal optimal quantum copying machine which optimally clones a single original qubit to N + 1 qubits.  ... 
arXiv:quant-ph/9801009v1 fatcat:k6fmoywdyvds3d74bs5nyffewq

Universal Optimal Cloning of Qubits and Quantum Registers [chapter]

V. BuŽek, M. Hillery
1999 Lecture Notes in Computer Science  
We also present network for an optimal quantum copying "machine" (transformation) which produces N + 1 identical copies from the original qubit.  ...  We review our recent work on the universal (i.e. input state independent) optimal quantum copying (cloning) of qubits.  ...  CONCLUSIONS We have presented the universal optimal quantum copying machine which optimally clones a single original qubit to N + 1 qubits.  ... 
doi:10.1007/3-540-49208-9_20 fatcat:7oeupus54ngjjpbsuoqtlnvbzm

Universal Optimal Cloning of Arbitrary Quantum States: From Qubits to Quantum Registers

Vladimír Bužek, Mark Hillery
1998 Physical Review Letters  
We discuss the properties of quantum clones. In particular, we show that in the limit of high dimension the fidelity of clones does not converge to zero but attains the limit 1͞2.  ...  We also show that our cloning transformation is most suitable for cloning of entanglement. [S0031-9007(98)  ...  the cloning transformation for qubits introduced in Ref  ... 
doi:10.1103/physrevlett.81.5003 fatcat:mokifhqa3rdelfmm2solbropuu

Optimal mirror phase-covariant cloning

Karol Bartkiewicz, Adam Miranowicz, Şahin Kaya Özdemir
2009 Physical Review A. Atomic, Molecular, and Optical Physics  
We propose a quantum cloning machine, which clones a qubit into two clones assuming known modulus of expectation value of Pauli Z-matrix.  ...  Quantum circuits implementing the optimal cloning transformation and their physical realization in a quantum-dot system are described.  ...  The research was conducted within the LFPPI network.  ... 
doi:10.1103/physreva.80.032306 fatcat:upkipwghz5edlayvzlfvkbe6fa

Optimal cloning of qubits given by an arbitrary axisymmetric distribution on the Bloch sphere

Karol Bartkiewicz, Adam Miranowicz
2010 Physical Review A. Atomic, Molecular, and Optical Physics  
We find an optimal quantum cloning machine, which clones qubits of arbitrary symmetrical distribution around the Bloch vector with the highest fidelity.  ...  Moreover, we show that the optimal phase-independent cloning machine can be implemented by modifying the mirror phase-covariant cloning machine for which quantum circuits are known.  ...  The optimal cloning machines are the UC [2] for case (a) and the PCC [9] for the other cases.  ... 
doi:10.1103/physreva.82.042330 fatcat:y2licxeekneffalilj3lzcckae

Coherence and entanglement under three qubit cloning operations [article]

Suchetana Goswami, Satyabrata Adhikari, A. S. Majumdar
2017 arXiv   pre-print
Coherent cloning operations on the other hand, could be used to construct a universal and optimal coherence machine.  ...  Here, we study the interplay of coherence and entanglement under the action of different three qubit quantum cloning operations.  ...  Thus, in case of the B-H quantum cloning machine, the generated cloned two qubit output is always coherent.  ... 
arXiv:1708.06492v1 fatcat:xdrrniqjwrdxxdwikdq6b25w3e

Quantum cloning machines and the applications

Heng Fan, Yi-Nan Wang, Li Jing, Jie-Dong Yue, Han-Duo Shi, Yong-Liang Zhang, Liang-Zhu Mu
2014 Physics reports  
Thus various quantum cloning machines have been designed for different quantum information protocols.  ...  Some well-known quantum cloning machines include universal quantum cloning machine, phase-covariant cloning machine, the asymmetric quantum cloning machine and the probabilistic quantum cloning machine  ...  We thank Jun Feng and Xi Chen for their careful reading this review and for numerous suggestions. We thank Ling-An Wu for helping us to fix the language problems.  ... 
doi:10.1016/j.physrep.2014.06.004 fatcat:vj7bcsrx5ff7vgb5ur5wlhqxym

Optimal quantum cloning via spin networks

Qing Chen, Jianhua Cheng, Ke-Lin Wang, Jiangfeng Du
2006 Physical Review A. Atomic, Molecular, and Optical Physics  
Moreover, we demonstrate that the same framework is capable for optimal 1->2 universal cloning.  ...  By properly designing the network and the couplings between spins, we show that optimal 1->M phase covariant cloning can be achieved without any external control.  ...  Nevertheless, in their proposal, the 1 → M PCC can reach the optimal result only in the case of M = 2, and for arbitrary M > 2 the fidelity of their PCC machine is far from the optimal bound.  ... 
doi:10.1103/physreva.74.034303 fatcat:6b66zqu5izfhfmlm2mqwcommha

Photonic quantum simulator for unbiased phase covariant cloning

Laura T. Knoll, Ignacio H. López Grande, Miguel A. Larotonda
2017 Applied physics B  
cloning machines by tuning the asymmetry on each of the cloning machines.  ...  Input polarization qubit states are cloned into path qubit states of the same photon, which is identified as a potential eavesdropper in a quantum key distribution protocol.  ...  Acknowledgments We acknowledge financial support from the Argentine funding agencies CONICET and ANPCyT. We thank Gabriel H. Aguilar for fruitful discussions.  ... 
doi:10.1007/s00340-017-6871-z fatcat:bywuyhilnzcsvo622wxpzwckxe

Quantum cloning machines and their implementation in physical systems

Tao Wu, Bao-Long Fang, Liu Ye
2013 Chinese Physics B  
As for the implementation of quantum cloning machines, we review some design methods and recent experimental results.  ...  We review the basic theory of approximate quantum cloning for discrete variables and some schemes for implementing quantum cloning machines.  ...  In both cases, the optimal cloning transformation is a unitary operation on two qubits: the input qubit and the blank qubit.  ... 
doi:10.1088/1674-1056/22/11/110311 fatcat:o42t2zjakzdzxehfo2oc42fini
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