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Author Grotz, Bernhard; Hauf, Moritz V.; Dankerl, Markus; Naydenov, Boris; Pezzagna, Sébastien; Meijer, Jan; Jelezko, Fedor; Wrachtrup, Jörg; Stutzmann, Martin; Reinhard, Friedemann; Garrido, Jose A.
Title Charge state manipulation of qubits in diamond Type Journal Article
Year 2012 Publication Nature Communications Abbreviated Journal Nat. Comm.
Volume 3 Issue 729 Pages 6
Keywords fromIPMRAS
Abstract (up) The nitrogen-vacancy (NV) centre in diamond is a promising candidate for a solid-state qubit. However, its charge state is known to be unstable, discharging from the qubit state NV- into the neutral state NV0 under various circumstances. Here we demonstrate that the charge state can be controlled by an electrolytic gate electrode. This way, single centres can be switched from an unknown non-fluorescent state into the neutral charge state NV0, and the population of an ensemble of centres can be shifted from NV0 to NV-. Numerical simulations confirm the manipulation of the charge state to be induced by the gate-controlled shift of the Fermi level at the diamond surface. This result opens the way to a dynamic control of transitions between charge states and to explore hitherto inaccessible states, such as NV+.
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Call Number RPLAB @ gujma @ Serial 770
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Author Collins, M. J.; Xiong, C.; Rey, I. H.; Vo, T. D.; He, J.; Shahnia, S.; Reardon, C.; Krauss, T. F.; Steel, M. J.; Clark, M.J.; & Eggleton, B.J.
Title Integrated spatial multiplexing of heralded single-photon sources Type Journal Article
Year 2013 Publication Nature Communications Abbreviated Journal
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Abstract (up) The non-deterministic nature of photon sources is a key limitation for single-photon quantum processors. Spatial multiplexing overcomes this by enhancing the heralded single-photon yield without enhancing the output noise. Here the intrinsic statistical limit of an individual source is surpassed by spatially multiplexing two monolithic silicon-based correlated photon pair sources in the telecommunications band, demonstrating a 62.4% increase in the her- alded single-photon output without an increase in unwanted multipair generation. We further demonstrate the scalability of this scheme by multiplexing photons generated in two waveguides pumped via an integrated coupler with a 63.1% increase in the heralded photon rate. This demonstration paves the way for a scalable architecture for multiplexing many photon sources in a compact integrated platform and achieving efficient two-photon inter- ference, required at the core of optical quantum computing and quantum communication protocols.
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Call Number RPLAB @ alex_kazakov @ Serial 1001
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Author Hadfield, Robert H.
Title Single-photon detectors for optical quantum information applications Type Journal Article
Year 2009 Publication Nature Photonics Abbreviated Journal Nature Photonics
Volume 3 Issue Pages 696-705
Keywords SPD
Abstract (up) The past decade has seen a dramatic increase in interest in new single-photon detector technologies. A major cause of this trend has undoubtedly been the push towards optical quantum information applications such as quantum key distribution. These new applications place extreme demands on detector performance that go beyond the capabilities of established single-photon detectors. There has been considerable effort to improve conventional photon-counting detectors and to transform new device concepts into workable technologies for optical quantum information applications. This Review aims to highlight the significant recent progress made in improving single-photon detector technologies, and the impact that these developments will have on quantum optics and quantum information science.
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Call Number RPLAB @ gujma @ Serial 678
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Author Lydersen, Lars; Wiechers, Carlos; Wittmann, Christoffer; Elser, Dominique; Skaar, Johannes; Makarov, Vadim
Title Hacking commercial quantum cryptography systems by tailored bright illumination Type Journal Article
Year 2010 Publication Nature Photonics Abbreviated Journal Nat. Photon.
Volume 4 Issue 10 Pages 686 - 689
Keywords quantum cryptography, hacking, QKD, APD
Abstract (up) The peculiar properties of quantum mechanics allow two remote parties to communicate a private, secret key, which is protected from eavesdropping by the laws of physics. So-called quantum key distribution (QKD) implementations always rely on detectors to measure the relevant quantum property of single photons. Here we demonstrate experimentally that the detectors in two commercially available QKD systems can be fully remote-controlled using specially tailored bright illumination. This makes it possible to tracelessly acquire the full secret key; we propose an eavesdropping apparatus built of off-the-shelf components. The loophole is likely to be present in most QKD systems using avalanche photodiodes to detect single photons. We believe that our findings are crucial for strengthening the security of practical QKD, by identifying and patching technological deficiencies.
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Call Number RPLAB @ gujma @ Serial 657
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Author Kosako, Terukazu; Kadoya, Yutaka; Hofmann, Holger F.
Title Directional control of light by a nano-optical Yagi–Uda antenna Type Journal Article
Year 2010 Publication Nature Photonics Abbreviated Journal Nat. Photon.
Volume 4 Issue Pages 312 - 315
Keywords optical antennas
Abstract (up) The plasmon resonance of metal nanoparticles can direct light from optical emitters in much the same way that radiofrequency antennas direct the emission from electrical circuits. Recently, rapid progress has been made in the realization of single-element antennas for optical waves. Because most of these devices are designed to optimize the local near-field coupling between the antenna and an emitter, the possibility of modifying the spatial radiation pattern has not yet received as much attention. In the radiofrequency regime, a typical antenna design for high directivity is the Yagi–Uda antenna, which essentially consists of a one-dimensional array of antenna elements driven by a single feed element. By fabricating a corresponding array of nanoparticles, similar radiation patterns can be obtained in the optical regime. Here, we present the experimental demonstration of directional control of radiation from a nano-optical Yagi–Uda antenna composed of appropriately tuned gold nanorods.
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Call Number RPLAB @ gujma @ Serial 747
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