Experimental phase-covariant cloning of polarization states of single photons

Cernoch, A; Bartůšková, Lucie; Soubusta, Jan; Ježek, Miroslav; Fiurášek, Jaromı́r; Dušek, Miloslav

doi:10.1103/physreva.74.042327

Cited by 50 publications

(42 citation statements)

References 28 publications

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“…In addition, much effort [6][7][8][9][10][11][12][13][14] has been devoted to the realization of the optimal approximations to quantum cloning machines (QCMs) since the seminal scheme of a universal quantum cloning machine (UQCM) was presented by Buzek and Hillery [3] in 1996. Recently, some experiments on quantum cloning have been reported [5,[15][16][17][18][19][20][21][22][23][24],…”

Section: Introductionmentioning

confidence: 99%

Implementing a quantum cloning machine in separate cavities via the optical coherent pulse as a quantum communication bus

Zhu

Liu

2015

Phys. Rev. A

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An efficient scheme is proposed to implement a quantum cloning machine in separate cavities based on a hybrid interaction between electron-spin systems placed in the cavities and an optical coherent pulse. The coefficient of the output state for the present cloning machine is just the direct product of two trigonometric functions, which ensures that different types of quantum cloning machine can be achieved readily in the same framework by appropriately adjusting the rotated angles. The present scheme can implement optimal one-to-two symmetric (asymmetric) universal quantum cloning, optimal symmetric (asymmetric) phase-covariant cloning, optimal symmetric (asymmetric) real-state cloning, optimal one-to-three symmetric economical real-state cloning, and optimal symmetric cloning of qubits given by an arbitrary axisymmetric distribution. In addition, photon loss of the qubus beams during the transmission and decoherence effects caused by such a photon loss are investigated.

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Section: Introductionmentioning

confidence: 99%

Implementing a quantum cloning machine in separate cavities via the optical coherent pulse as a quantum communication bus

Zhu

Liu

2015

Phys. Rev. A

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“…Its major advantage is high experimental accessibility and relatively low cost [2]. Hence many of the most important quantum information protocols, like teleportation [3], cloning [4][5][6][7], and various quantum gates [2,[8][9][10][11], have been demonstrated using individual photons and linear-optical components. On the other hand, linearoptical quantum computing is burdened by two significant drawbacks related to its probabilistic nature [12][13][14]: first, the success probability decreases exponentially with the number of quantum gates, and second, in a large number of cases there is a need for postselection in order to distinguish the successful and unsuccessful operations of these probabilistic gates.…”

Section: Introductionmentioning

confidence: 99%

Entanglement-assisted scheme for nondemolition detection of the presence of a single photon

Bula¹,

Bartkiewicz²,

Cernoch³

et al. 2013

Phys. Rev. A

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In this paper, we propose a resources-optimal linear-optical scheme for quantum nondemolition detection of single-photon presence. By measuring the state of ancillary photons, the presence of a photon in signal mode is revealed with a success probability of 1/2 without any disturbance to its state. We also show how to tune the setup to perform quantum nondemolition measurement of the signal photon state, and we provide tradeoff between the extracted information and the signal state disturbance. Moreover, the optimality of resources and methods by which to increase the success probability are discussed.

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“…1. A pair of signal and ancilla photons is prepared by means of frequency-degenerate type-I spontaneous parametric down-conversion in a 10-mm-long LiIO 3 nonlinear crystal pumped by a krypton-ion cw laser (413.1 nm), similarly as in our previous experiments [16,17]. The signal photon is split by a fiber coupler FC into two fibers.…”

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confidence: 96%

Fiber-Optics Implementation of an Asymmetric Phase-Covariant Quantum Cloner

et al. 2007

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We present the experimental realization of optimal symmetric and asymmetric phase-covariant 1 → 2 cloning of qubit states using fiber optics. State of each qubit is encoded into a single photon which can propagate through two optical fibers. The operation of our device is based on one-and two-photon interference. We have demonstrated creation of two copies of any state of a qubit from the equator of the Bloch sphere. The measured fidelities of both copies are close to the theoretical values and they surpass the theoretical maximum obtainable with the universal cloner.PACS numbers: 03.67.-a, 42.50.-p, 32.80.-t The quantum no-cloning theorem [1] lies at the heart of quantum information theory. The apparently simple observation that perfect copying of unknown quantum states is impossible has profound consequences. On the fundamental side, it prevents superluminal communication with entangled states, thereby guaranteeing the peaceful coexistence of quantum mechanics and theory of relativity. On the practical side, this theorem is behind the security of the quantum key distribution schemes which rely on the fact that any attempt to measure or copy an unknown quantum state results in the disturbance of this state. Going beyond the no-cloning theorem, Bužek and Hillery in a seminal paper introduced the concept of the universal approximate quantum cloning machine that optimally approximates the forbidden transformation |ψ → |ψ |ψ [2]. Today, optimal quantum cloners are known for many different cases and scenarios [3,4]. During recent years, growing attention has been paid to the experimental implementation of quantum cloning machines and, in particular, optimal cloning of polarization states of single photons via stimulated parametric downconversion or via photon bunching on a beam splitter has been successfully demonstrated [5,6,7,8,9,10].Besides giving an insight into the fundamental limits on distribution of quantum information, the quantum cloning machines turned out to be very efficient eavesdropping attacks on the quantum key distribution protocols [11,12,13,14]. In this context one is particularly interested in the asymmetric quantum cloners that produce two copies with different fidelities. In this way, the eavesdropper can control the trade-off between the information gained on a secret cryptographic key and the amount of noise added to the copy which is sent down the channel to the authorized receiver. While the theory of optimal asymmetric quantum copying machines is well established (see, e.g. the recent reviews [3,4]), the experimental optical realization of such machines has received considerably less attention. This might be attributed to the fact that the asymmetric cloning operations exhibit much less symmetry than the corresponding symmetric ones. To the best of our knowledge, asymmetric quantum cloning of single-photon states has been so far achieved only in a single experiment, where universal asymmetric copying of polarization states was performed by means of partial quantum teleportation [15].In...

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Experimental phase-covariant cloning of polarization states of single photons

Cited by 50 publications

References 28 publications

Implementing a quantum cloning machine in separate cavities via the optical coherent pulse as a quantum communication bus

Implementing a quantum cloning machine in separate cavities via the optical coherent pulse as a quantum communication bus

Entanglement-assisted scheme for nondemolition detection of the presence of a single photon

Fiber-Optics Implementation of an Asymmetric Phase-Covariant Quantum Cloner

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