Quantum cloning and teleportation criteria for continuous quantum variables

Grosshans, Frédéric; Grangier, Philippe

doi:10.1103/physreva.64.010301

Cited by 218 publications

(257 citation statements)

References 27 publications

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“…The criteria of CV cloning and teleportation are studied in (Grosshans and Grangier, 2001). We remark again that the reviews of CV quantum information can be found in (Braunstein and van Loock, 2005;Wang et al, 2007;Weedbrook et al, 2012).…”

Section: E Other Developments and Related Topicsmentioning

confidence: 99%

Quantum cloning machines and the applications

et al. 2014

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No-cloning theorem is fundamental for quantum mechanics and for quantum information science that states an unknown quantum state cannot be cloned perfectly. However, we can try to clone a quantum state approximately with the optimal fidelity, or instead, we can try to clone it perfectly with the largest probability. Thus various quantum cloning machines have been designed for different quantum information protocols. Specifically, quantum cloning machines can be designed to analyze the security of quantum key distribution protocols such as BB84 protocol, six-state protocol, B92 protocol and their generalizations. 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 etc. In the past years, much progress has been made in studying quantum cloning machines and their applications and implementations, both theoretically and experimentally. In this review, we will give a complete description of those important developments about quantum cloning and some related topics. On the other hand, this review is self-consistent, and in particular, we try to present some detailed formulations so that further study can be taken based on those results.

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Section: E Other Developments and Related Topicsmentioning

confidence: 99%

Quantum cloning machines and the applications

et al. 2014

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“…The main part of the noise is constant (dark counts), whilst the main change of the signal is due to photon loss in the fibre. An alternative method for distilling a key is called reverse conciliation [19,20], and was previously used in continuous variable quantum cryptography. As we shall see, this allows secure keys at longer distances than the conventional forward reconciliation.…”

Section: Why Distance Is a Problemmentioning

confidence: 99%

Quantum relays for long distance quantum cryptography

Collins¹,

Gisin²,

Riedmatten³

2005

Journal of Modern Optics

117

112

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Quantum Cryptography is on the verge of commercial application. One of its greatest limitations is over long distance -secret key rates are low and the longest fibre over which any key has been exchanged is currently 100 km. We investigate the quantum relay, which can increase the maximum distance at which quantum cryptography is possible. The relay splits the channel into sections, and sends a different photon across each section, increasing the signal to noise ratio. The photons are linked as in teleportation, with entangled photon pairs and Bell measurements. We show that such a scheme could allow cryptography over hundreds of kilometers with today's detectors. It could not, however, improve the rate of key exchange over distances where the standard single section scheme already works. We also show that reverse key reconciliation, previously used in continuous variable quantum cryptography, gives a secure key over longer distances than forward key reconciliation.

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“…First, we review another criterion for quantum EPR-like correlations introduced by Reid and Drummond [12]. For the discussions about this EPR condition and about the nonseparability criterion see [17,13] and references therein. The EPR criterion refers to the demonstration of the EPR paradox for continuous variables and specifies the ability to infer "at a distance" either of the two non-commuting signal observables with a precision below the vacuum noise level of the signal beam [12].…”

Section: Fig 1 Qkd With Bright Epr-entangled Beams (See Text)mentioning

confidence: 99%

Quantum Key Distribution with Bright Entangled Beams

2002

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We suggest a quantum cryptographic scheme using continuous EPR-like correlations of bright optical beams. For binary key encoding, the continuous information is discretized in a novel way by associating a respective measurement, amplitude or phase, with a bit value "1" or "0". The secure key distribution is guaranteed by the quantum correlations. No pre-determined information is sent through the quantum channel contributing to the security of the system. Quantum key distribution (QKD) is the most advanced technology in the field of quantum information processing. The conventional arrangements use dichotomic quantum systems to realize the secure information transfer (for a review see [1]). These discrete systems have the advantage to be in principle loss insensitive in terms of security. However, the generation process for entangled photon pairs needed for QKD based on EPR correlations is spontaneous and therefore probabilistic. This limits the achievable data transmission rates.A new development employs continuous variable systems [2][3][4][5], such as intense light fields, to obtain shorter key distribution times. The security issues of continuous variable quantum cryptography have been addressed [6,7] and it was proven that the secure key distribution can be achieved using continuous EPR-type correlation or quantum squeezed states.In this Letter we propose a new key distribution scheme based on the quantum EPR-like correlations of conjugate continuous variables. The main novel feature of the protocol [8] is an assignment of a bit value to the type of measurement. The binary bits are encoded by the choice to detect either of two conjugate variables accomplished independently and randomly by both communicating parties. This serves as a discretization of continuous information in the measurement process. The coincidences in the choices of both parties are revealed by testing the EPR-like correlations between the beams and contribute to the key. Thus, in contrast to other continuous variable systems [2][3][4][5], the basis value is not predetermined but develops in measurements at receiver and sender stations, resembling the EPR-based Ekert protocol for discrete cryptographic systems. The detection of light statistics performed by both communicating parties plays a decisive role in the proposed scheme. It comprises bit encoding, key sifting, monitoring of the disturbance in the quantum channel and active control on timing and information flow during the transmission [9].The basic ingredient of the scheme are quantum correlations between the amplitudeX j =â † j +â j and phase Y j = i(â † j −â j ) quadratures of bright beams j = 1, 2. Because of the high intensity of the optical fields involved, we use the linearization approach throughout the paper:The entangled observables are then the quantum uncertainties in the respective field quadratures. We start with the definition of the relevant measured quantities and of the conditions for appling the two-mode correlations as a quantum resource. It can be done on the bas...

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Quantum cloning and teleportation criteria for continuous quantum variables

Cited by 218 publications

References 27 publications

Quantum cloning machines and the applications

Quantum cloning machines and the applications

Quantum relays for long distance quantum cryptography

Quantum Key Distribution with Bright Entangled Beams

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