Quantum Dense Coding and Quantum Teleportation

Bouwmeester, Dirk; Weinfurter, Harald; Zeilinger, Anton

doi:10.1007/978-3-662-04209-0_3

Cited by 24 publications

(22 citation statements)

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“…During the years 1998-2003, Adams and collaborators conducted a series of experiments and improved the coincidence count rate to about 1 count per 13 seconds [4]. Recent and expected improvements in brilliance and beam quality of synchrotron x-ray sources, together with new facilities such as the x-ray free electron laser and energy recovering linacs [4], offer the possibility of extending the concepts of quantum optics as developed in the visible portion of the electromagnetic spectrum [5] to x-ray wavelengths.…”

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confidence: 99%

Polarization Entangled Photons at X-Ray Energies

Shwartz

Harris

2011

Phys. Rev. Lett.

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We show that polarization entangled photons at x-ray energies can be generated via spontaneous parametric down conversion. Each of the four Bell states can be generated by choosing the angle of incidence and polarization of the pumping beam.PACS numbers: 03.65. Ud, 42.50.Dv, 42.65.Lm Spontaneous parametric down-conversion at hard xray energies was first proposed by Freund and Levine in 1969 [1], and first demonstrated experimentally by Eisenberger and McCall about two years latter [2]. In that work a hard x-ray tube was used as the pump, and coincidence counts at the signal and idler were measured at the rate of a few counts per hour. The first experiment using a synchrotron was done in 1997 by Yoda et al. [3] with a counting rate of 6 counts per hour. During the years 1998-2003, Adams and collaborators conducted a series of experiments and improved the coincidence count rate to about 1 count per 13 seconds [4]. Recent and expected improvements in brilliance and beam quality of synchrotron x-ray sources, together with new facilities such as the x-ray free electron laser and energy recovering linacs [4], offer the possibility of extending the concepts of quantum optics as developed in the visible portion of the electromagnetic spectrum [5] to x-ray wavelengths.As a step toward this extension, this Letter describes a method for generating polarization entangled photons, in pure Bell states, at x-ray wavelengths. The technique is straight-forward and makes use of the selection rules that are associated with a phase matched plasma-like xray nonlinearity [4]. In the following paragraphs we will show that by choosing the polarization and angle of incidence of the pumping beam, and working off of the degenerate frequency, that each of the four Bell states may be generated. A consequence of this work is that, in each of the previous x-ray down conversion experiments mentioned above, the generated photon pairs were polarization entangled, but in no case were they in a pure Bell's state.Before proceeding we note two previous suggestions for generating entangled photons at x-ray energies. The first is a proposal by Schützhold et al. who have suggested the use of ultra-relativistic electrons accelerated by a strong periodic electromagnetic field (for example, a laser or undulator) to create entangled photon pairs in the multikeV regime [6]. The second is a proposal by Pàlffy et al. who suggest generating single-photon entangles states by control of nuclear forward scattering [7].We start by discussing the nonlinearity. The central concept of the nonlinearity at x-ray energies is that, since x-ray photons have energies that are large as compared to the electron binding energy of low-Z atoms, that the x-ray nonlinearity of an element such as diamond may be calculated by treating all of the electrons in the atom as free particles, and therefore treating the nonlinear medium as a very dense cold plasma [1,2]. This x-ray nonlinearity is of second order so that two frequencies may add or subtract to generate a third frequen...

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confidence: 99%

Polarization Entangled Photons at X-Ray Energies

Shwartz

Harris

2011

Phys. Rev. Lett.

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“…Bennett from IBM and G. Brassard from Montreal University introduced the first QKD protocol (Bennett & Brassard, 1984), which has become an alternative solution for the problem of key distribution. This protocol is called BB84 (Bouwmeester et al, 2000) and it refers to QKD protocols using single qubits. The states of these qubits are the polarisation states of single photons.…”

Section: Main Approaches To Quantum Secure Telecommunication Systems mentioning

confidence: 99%

“…Quantum key distribution (QKD) (Bennett, 1992;Bennett et al, 1992;Bennett et al, 1995;Bennett & Brassard, 1984;Bouwmeester et al, 2000;Gisin et al, 2002;Lütkenhaus & Shields, 2009;Scarani et al, 2009;Vasiliu & Vorobiyenko 2006;Williams, 2011) plays a dominant role in QC. The overwhelming majority of theoretic and practical research projects in QC are related to the development of QKD protocols.…”

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confidence: 99%

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Quantum Secure Telecommunication Systems

Корченко¹,

Vorobiyenko²,

Lutskiy³

et al. 2012

Telecommunications Networks - Current Status and Future Trends

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“…Applications range from problems in scheduling and asset management to control and estimation of dynamical systems (1). In this article we use these techniques for solving a class of decision-making problems that arise in quantum information science (2,3). Specifically we consider the optimal design of a so-called quantum repeater for quantum communication.…”

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confidence: 99%

Optimal approach to quantum communication using dynamic programming

Jiang¹,

Taylor

Khaneja

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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Reliable preparation of entanglement between distant systems is an outstanding problem in quantum information science and quantum communication. In practice, this has to be accomplished by noisy channels (such as optical fibers) that generally result in exponential attenuation of quantum signals at large distances. A special class of quantum error correction protocols, quantum repeater protocols, can be used to overcome such losses. In this work, we introduce a method for systematically optimizing existing protocols and developing more efficient protocols. Our approach makes use of a dynamic programmingbased searching algorithm, the complexity of which scales only polynomially with the communication distance, letting us efficiently determine near-optimal solutions. We find significant improvements in both the speed and the final-state fidelity for preparing long-distance entangled states.entanglement ͉ optimal control ͉ quantum information ͉ quantum repeater S equential decision-making in probabilistic systems is a widely studied subject in the field of economics, management science, and engineering. Applications range from problems in scheduling and asset management to control and estimation of dynamical systems (1). In this article we use these techniques for solving a class of decision-making problems that arise in quantum information science (2, 3). Specifically we consider the optimal design of a so-called quantum repeater for quantum communication. Such repeaters have potential application in quantum communication protocols for cryptography (4-6) and information processing (7), where entangled quantum systems located at distant locations are used as a fundamental resource. In principle, this entanglement can be generated by sending a pair of entangled photons through optical fibers. However, in the presence of attenuation, the probability of success in preparing a distant entangled pair decreases exponentially with distance (8).Quantum repeaters can reduce such exponential scaling to polynomial scaling with distance and thus provide an avenue to long-distance quantum communication even with fiber attenuation. The underlying idea of quantum repeater (9, 10) is to generate a backbone of entangled pairs over much shorter distances, store them in a set of distributed nodes, and perform a sequence of quantum operations with only a finite probability of success. Purification operations (11, 12) improve the fidelity of the entanglement in the backbone, and connection operations join two shorter-distance entangled pairs of the backbone to form a single, longer-distance entangled pair. By relying on a quantum memory at each node to let different sections of the repeater reattempt failed operations independently, a high-fidelity entangled state between two remote quantum systems can be produced in polynomial time. A quantum repeater protocol is a set of rules that determine the choice and ordering of operations based on previous results. An optimal protocol is one that produces entangled pairs of a desired fidelity ...

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Quantum Dense Coding and Quantum Teleportation

Cited by 24 publications

References 0 publications

Polarization Entangled Photons at X-Ray Energies

Polarization Entangled Photons at X-Ray Energies

Quantum Secure Telecommunication Systems

Optimal approach to quantum communication using dynamic programming

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