Quantum cryptography

Gisin, Nicolas; Ribordy, G.; Tittel, Wolfgang; Zbinden, Hugo

doi:10.1103/revmodphys.74.145

Cited by 7,640 publications

(6,686 citation statements)

References 191 publications

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“…Semiconductor quantum dots (QDs) are feasible photon emitters for QIA due to their atomic-like energy structure and their possibility to be integrated with other semiconductor devices on the same chip. Site-controlled QDs operating close to room temperature are demanded for widespread applications, and linearly polarized emitters are a prerequisite for certain QIA [1,2].…”

Section: Introductionmentioning

confidence: 99%

Polarized single photon emission and photon bunching from an InGaN quantum dot on a GaN micropyramid

Jemsson

Machhadani²,

Holtz³

et al. 2015

Nanotechnology

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We report on excitonic single photon emission and biexcitonic photon bunching from an InGaN quantum dot formed on the apex of a hexagonal GaN micropyramid. An approach to suppress uncorrelated emission from the pyramid base is proposed, a metal film is demonstrated to effectively screen background emission and thereby significantly enhance the signal-to-background ratio of the quantum dot emission. As a result, the second order coherence function at zero time delay g (2) (0) is significantly reduced (to g (2) (0) = 0.24, raw value) for the excitonic autocorrelation at a temperature of 12 K under continuous wave excitation, and a dominating single photon emission is demonstrated to survive up to 50 K. The deterioration of the g (2) (0)-value at elevated temperatures is well understood as the combined effect of reduced signal-to-background ratio and limited time resolution of the setup. This result underlines the great potential of site controlled pyramidal dots as sources of fast polarized single photons.

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Section: Introductionmentioning

confidence: 99%

Polarized single photon emission and photon bunching from an InGaN quantum dot on a GaN micropyramid

Jemsson

Machhadani²,

Holtz³

et al. 2015

Nanotechnology

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show abstract

“…T he quantum interference 1 of two indistinguishable single photons is an important resource for long distance quantum communication and linear quantum computing [2][3][4][5] . Recent years have seen important progress in the development of bright single-photon sources in solid-state systems using semiconductor self-assembled quantum dots (QDs) 6 inserted in photonic structures [7][8][9][10] .…”

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confidence: 99%

Bright solid-state sources of indistinguishable single photons

et al. 2013

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Bright sources of indistinguishable single photons are strongly needed for the scalability of quantum information processing. Semiconductor quantum dots are promising systems to build such sources. Several works demonstrated emission of indistinguishable photons while others proposed various approaches to efficiently collect them. Here we combine both properties and report on the fabrication of ultrabright sources of indistinguishable single photons, thanks to deterministic positioning of single quantum dots in well-designed pillar cavities. Brightness as high as 0.79±0.08 collected photon per pulse is demonstrated. The indistinguishability of the photons is investigated as a function of the source brightness and the excitation conditions. We show that a two-laser excitation scheme allows reducing the fluctuations of the quantum dot electrostatic environment under high pumping conditions. With this method, we obtain 82 ± 10% indistinguishability for a brightness as large as 0.65 ± 0.06 collected photon per pulse.

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“…[1][2][3][4] Integrating these components onto a single chip would realize quantum photonic devices that enable quantum communication networks, 1,2 photonic quantum computers, 5,6 and photonic quantum simulators. [7][8][9] Many of these applications rely on optical qubits that exhibit two-photon quantum interference on a beamsplitter, the primary mechanism for achieving effective photon-photon interactions.…”

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confidence: 99%

Two-Photon Interference from the Far-Field Emission of Chip-Integrated Cavity-Coupled Emitters

et al. 2016

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ABSTRACT. Interactions between solid-state quantum emitters and cavities are important for a broad range of applications in quantum communication, linear optical quantum computing, nonlinear photonics, and photonic quantum simulation. These applications often require combining many devices on a single chip with identical emission wavelengths in order to generate two-photon interference, the primary mechanism for achieving effective photon-photon interactions. Such integration remains extremely challenging due to inhomogeneous broadening and fabrication errors that randomize the resonant frequencies of both the emitters and cavities. In this letter we demonstrate two-photon interference from independent cavity-coupled emitters on the same chip, providing a potential solution to this long-standing problem. We overcome spectral mismatch between different cavities due to fabrication errors by depositing and locally evaporating a thin layer of condensed nitrogen. We integrate optical heaters to tune individual dots within each cavity to the same resonance with better than 3 µeV of precision. Combining these tuning methods, we demonstrate two-photon interference between two devices spaced by less than 15 µm on the same chip with a post-selected visibility of 33%. These results pave the way to integrate multiple quantum light sources on the same chip to develop quantum photonic devices.

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Quantum cryptography

Abstract: Quantum cryptography could well be the first application of quantum mechanics at the individual quanta level. The very fast progress in both theory and experiments over the recent years are reviewed, with emphasis on open questions and technological issues.

Cited by 7,640 publications

References 191 publications

Polarized single photon emission and photon bunching from an InGaN quantum dot on a GaN micropyramid

Polarized single photon emission and photon bunching from an InGaN quantum dot on a GaN micropyramid

Bright solid-state sources of indistinguishable single photons

Two-Photon Interference from the Far-Field Emission of Chip-Integrated Cavity-Coupled Emitters

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