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Author Ikuta, Rikizo; Kusaka, Yoshiaki; Kitano, suyoshi; Kato, Hiroshi; Yamamoto, Takashi; Koashi, Masato; Imoto, Nobuyuki
Title (down) Wide-band quantum interface for visible-totelecommunication wavelength conversion Type Journal Article
Year 2011 Publication Nature Communications Abbreviated Journal Nat. Comm.
Volume 2 Issue Pages 5
Keywords fromIPMRAS
Abstract Although near-infrared photons in telecommunication bands are required for long-distance quantum communication, various quantum information tasks have been performed by using visible photons for the past two decades. Recently, such visible photons from diverse media including atomic quantum memories have also been studied. Optical frequency down-conversion from visible to telecommunication bands while keeping the quantum states is thus required for bridging such wavelength gaps. Here we report demonstration of a quantum interface of frequency down-conversion from visible to telecommunication bands by using a nonlinear crystal, which has a potential to work over wide bandwidths, leading to a high-speed interface of frequency conversion. We achieved the conversion of a picosecond visible photon at 780 nm to a 1,522-nm photon, and observed that the conversion process retained entanglement between the down-converted photon and another photon.
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Call Number RPLAB @ gujma @ Serial 764
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Author Knee, George C.; Simmons, Stephanie; Gauger, Erik M.; Morton, John J. L.; Riemann, Helge; Abrosimov, Nikolai V.; Becker, Peter; Pohl, Hans-Joachim; Itoh, Kohei M.; Thewalt, Mike L. W.; Briggs, G. Andrew D.; Benjamin, Simon C.
Title (down) Violation of a Leggett–Garg inequality with ideal non-invasive measurements Type Journal Article
Year 2012 Publication Nature Communications Abbreviated Journal Nat. Comm.
Volume 3 Issue 606 Pages 6
Keywords fromIPMRAS
Abstract The quantum superposition principle states that an entity can exist in two different states simultaneously, counter to our 'classical' intuition. Is it possible to understand a given system's behaviour without such a concept? A test designed by Leggett and Garg can rule out this possibility. The test, originally intended for macroscopic objects, has been implemented in various systems. However to date no experiment has employed the 'ideal negative result' measurements that are required for the most robust test. Here we introduce a general protocol for these special measurements using an ancillary system, which acts as a local measuring device but which need not be perfectly prepared. We report an experimental realization using spin-bearing phosphorus impurities in silicon. The results demonstrate the necessity of a non-classical picture for this class of microscopic system. Our procedure can be applied to systems of any size, whether individually controlled or in a spatial ensemble.
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Call Number RPLAB @ gujma @ Serial 767
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Author Hosseini, M.; Campbell, G.; Sparkes, B. M.; Lam, P. K.; Buchler, B. C.
Title (down) Unconditional room-temperature quantum memory Type Journal Article
Year 2011 Publication Nature Physics Abbreviated Journal Nat. Phys.
Volume 7 Issue 10 Pages 794-798
Keywords fromIPMRAS
Abstract Just as classical information systems require buffers and memory, the same is true for quantum information systems. The potential that optical quantum information processing holds for revolutionizing computation and communication is therefore driving significant research into developing optical quantum memory. A practical optical quantum memory must be able to store and recall quantum states on demand with high efficiency and low noise. Ideally, the platform for the memory would also be simple and inexpensive. Here, we present a complete tomographic reconstruction of quantum states that have been stored in the ground states of rubidium in a vapour cell operating at around 80 °C. Without conditional measurements, we show recall fidelity up to 98% for coherent pulses containing around one photon. To unambiguously verify that our memory beats the quantum no-cloning limit we employ state-independent verification using conditional variance and signal-transfer coefficients.
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Call Number RPLAB @ gujma @ Serial 824
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Author Nozaki, Kengo; Shinya, Akihiko; Matsuo, Shinji; Suzaki, Yasumasa; Segawa, Toru; Sato, Tomonari; Kawaguchi, Yoshihiro; Takahashi, Ryo; Notomi, Masaya
Title (down) Ultralow-power all-optical RAM based on nanocavities Type Journal Article
Year 2012 Publication Nature Photonics Abbreviated Journal Nat. Photon.
Volume 6 Issue 4 Pages 248-252
Keywords fromIPMRAS
Abstract Optical random-access memory (o-RAM) has been regarded as one of the most difficult challenges in terms of replacing its various functionalities in electronic circuitry with their photonic counterparts. Nevertheless, it constitutes a key device in optical routing and processing. Here, we demonstrate that photonic crystal nanocavities with an ultrasmall buried heterostructure design can solve most of the problems encountered in previous o-RAMs. By taking advantage of the strong confinement of photons and carriers and allowing heat to escape efficiently, we have realized all-optical RAMs with a power consumption of only 30 nW, which is more than 300 times lower than the previous record, and have achieved continuous operation. We have also demonstrated their feasibility in multibit integration. This paves the way for constructing a low-power large-scale o-RAM system that can handle high-bit-rate optical signals.
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Call Number RPLAB @ gujma @ Serial 786
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Author Pris, Andrew D.; Utturkar, Yogen; Surman, Cheryl; Morris, William G.; Vert, Alexey; Zalyubovskiy, Sergiy; Deng, Tao; Ghiradella, Helen T.; Potyrailo, Radislav A.
Title (down) Towards high-speed imaging of infrared photons with bio-inspired nanoarchitectures Type Journal Article
Year 2012 Publication Nature Photonics Abbreviated Journal Nat. Photon.
Volume 6 Issue 3 Pages 195-200
Keywords fromIPMRAS
Abstract Existing infrared detectors rely on complex microfabrication and thermal management methods. Here, we report an attractive platform of low-thermal-mass resonators inspired by the architectures of iridescent Morpho butterfly scales. In these resonators, the optical cavity is modulated by its thermal expansion and refractive index change, resulting in `wavelength conversion' of mid-wave infrared (3-8 µm) radiation into visible iridescence changes. By doping Morpho butterfly scales with single-walled carbon nanotubes, we achieved mid-wave infrared detection with 18-62 mK noise-equivalent temperature difference and 35-40 Hz heat-sink-free response speed. The nanoscale pitch and the extremely small thermal mass of individual `pixels' promise significant improvements over existing detectors. Computational analysis explains the origin of this thermal response and guides future conceptually new bio-inspired thermal imaging sensor designs.
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Call Number RPLAB @ gujma @ Serial 785
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