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181 results on '"O'Brien, J.L."'

1. Quantum computers

Author

Ladd, T.D., Jelezko, F., Laflamme, R., Nakamura, Y., Monroe, C., and O'Brien, J.L.

Subjects
Atoms -- Electric properties, Quantum theory -- Analysis, Superconductors -- Analysis, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Over the past several decades, quantum information science has emerged to seek answers to the question: can we gain some advantage by storing, transmitting and processing information encoded in systems that exhibit unique quantum properties? Today it is understood that the answer is yes, and many research groups around the world are working towards the highly ambitious technological goal of building a quantum computer, which would dramatically improve computational power for particular tasks. A number of physical systems, spanning much of modern physics, are being developed for quantum computation. However, it remains unclear which technology, if any, will ultimately prove successful. Here we describe the latest developments for each of the leading approaches and explain the major challenges for the future., In the past decade, there has been tremendous progress in the experimental development of a quantum computer: a machine that would exploit the full complexity of a many-particle quantum wavefunction [...]

Published
2010
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3. Chip-based quantum key distribution

Author

Sibson, P., Erven, C., Godfrey, M., Miki, S., Yamashita, T., Fujiwara, M., Sasaki, M., Terai, H., Tanner, M.G., Natarajan, C.M., Hadfield, R.H., O'Brien, J.L., and Thompson, M.G.

Subjects
Science, Phase (waves), FOS: Physical sciences, General Physics and Astronomy, 02 engineering and technology, Quantum key distribution, Bioinformatics, Bristol Quantum Information Institute, 01 natural sciences, Article, General Biochemistry, Genetics and Molecular Biology, QETLabs, Optics, 0103 physical sciences, 010306 general physics, Quantum, Computer Science::Information Theory, Physics, Quantum Physics, Multidisciplinary, business.industry, Transmitter, Detector, General Chemistry, 021001 nanoscience & nanotechnology, Chip, Pulse (physics), Quantum cryptography, Quantum Physics (quant-ph), 0210 nano-technology, business
Abstract

Improvement in secure transmission of information is an urgent practical need for governments, corporations and individuals. Quantum key distribution (QKD) promises security based on the laws of physics and has rapidly grown from proof-of-concept to robust demonstrations and even deployment of commercial systems. Despite these advances, QKD has not been widely adopted, and practical large-scale deployment will likely require integrated chip-based devices for improved performance, miniaturisation and enhanced functionality, fully integrated into classical communication networks. Here we report low error rate, GHz clocked QKD operation of an InP transmitter chip and a SiO$_x$N$_y$ receiver chip --- monolithically integrated devices that use state-of-the-art components and manufacturing processes from the telecom industry. We use the reconfigurability of these devices to demonstrate three important QKD protocols --- BB84, Coherent One Way (COW) and Differential Phase Shift (DPS) --- with performance comparable to state-of-the-art. These devices, when combined with integrated single photon detectors, satisfy the requirements at each of the levels of future QKD networks --- from point-of-use through to backbone --- and open the way to operation in existing and emerging classical communication networks., 5 pages, 3 figures, 1 table

Published
2017

5. On-chip quantum interference between silicon photon-pair sources

Author

Silverstone, J.W., Bonneau, D., Ohira, K., Suzuki, N., Yoshida, H., Iizuka, N., Ezaki, M., Natarajan, C.M., Tanner, M.G., Hadfield, R.H., Zwiller, V., Marshall, G.D., Rarity, J.G., O'Brien, J.L., and Thompson, M.G.

Subjects
Computer Science::Hardware Architecture, Physics::Optics
Abstract

Large-scale integrated quantum photonic technologies1, 2 will require on-chip integration of identical photon sources with reconfigurable waveguide circuits. Relatively complex quantum circuits have been demonstrated already1, 2, 3, 4, 5, 6, 7, but few studies acknowledge the pressing need to integrate photon sources and waveguide circuits together on-chip8, 9. A key step towards such large-scale quantum technologies is the integration of just two individual photon sources within a waveguide circuit, and the demonstration of high-visibility quantum interference between them. Here, we report a silicon-on-insulator device that combines two four-wave mixing sources in an interferometer with a reconfigurable phase shifter. We configured the device to create and manipulate two-colour (non-degenerate) or same-colour (degenerate) path-entangled or path-unentangled photon pairs. We observed up to 100.0 ± 0.4% visibility quantum interference on-chip, and up to 95 ± 4% off-chip. Our device removes the need for external photon sources, provides a path to increasing the complexity of quantum photonic circuits and is a first step towards fully integrated quantum technologies.

Published
2014

6. Silicon quantum photonics

Author

Silverstone, J.W., primary, Wang, J., additional, Bonneau, D., additional, Sibson, P., additional, Santagati, R., additional, Erven, C., additional, O'Brien, J.L., additional, and Thompson, M.G., additional

Published
2016
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7. Bayesian quantum phase estimation on an integrated Silicon photonic device

Author

Paesani, S., primary, Gentile, A. A., additional, Santagati, R., additional, Wang, J., additional, Wiebe, N., additional, Miki, S., additional, Yamashita, T., additional, Terai, H., additional, Fujiwara, M., additional, Sasaki, M., additional, Tanner, M. G., additional, Natarajan, C. M., additional, Hadfield, R. H., additional, Tew, D., additional, O’Brien, J.L., additional, and Thompson, M. G., additional

Published
2016
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8. Multi-particle Quantum Walks with 2D & 3D Arrayed Waveguides

Author

Poulios, K., Fry, D., Lobino, M., Matthews, J.C.F., Meinecke, J.D.A., Peruzzo, A., Zhou, X., Thompson, M.G., O'Brien, J.L., Politi, A., Keil, R., Szameit, A., Ismail, N., Worhoff, Kerstin, and Matsuda, N.

Subjects
Quantum walk, Mathematics::Probability, METIS-286338, integrated waveguides, IOMS-PIT: PHOTONICS INTEGRATION TECHNOLOGY, direct write, EWI-21787, IR-80304
Abstract

Multi-photon quantum walks on integrated circuits are emonstrated, showing non-classical correlations, in one and two dimensional networks. Time evolution of quantum walks and a scheme for simulating fermionic quantum walks using entanglement are demonstrated.

Published
2012

9. Chip-scale integrated quantum technologies

Author

Erven, C., primary, Sibson, P., additional, Santagati, R., additional, Silverstone, J.W., additional, Wang, J., additional, Bonneau, D., additional, O'Brien, J.L., additional, and Thompson, M.G., additional

Published
2015
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11. Photon pair generation and manipulation in an integrated silicon chip

Author

Bonneau, D. (author), Silverstone, J.W. (author), Hadfield, R.H. (author), Zwiller, V. (author), Ohira, K. (author), Suzuki, N. (author), Yoshida, H. (author), Iizuka, N. (author), Ezaki, M. (author), Rarity, J.G. (author), O'Brien, J.L. (author), Thompson, M.G. (author), Bonneau, D. (author), Silverstone, J.W. (author), Hadfield, R.H. (author), Zwiller, V. (author), Ohira, K. (author), Suzuki, N. (author), Yoshida, H. (author), Iizuka, N. (author), Ezaki, M. (author), Rarity, J.G. (author), O'Brien, J.L. (author), and Thompson, M.G. (author)

Abstract

Quantum photonics is a promising technology for implementing quantum information tasks. We demonstrate integration of multiple photon pair sources together with a circuit enabling creation and manipulation of photon pairs in a monolithic silicon-on-insulator chip., QN/Quantum Nanoscience, Applied Sciences

Published
2013
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12. Fast Path and Polarization Manipulation of Telecom Wavelength Single Photons in Lithium Niobate Waveguide Devices

Author

Bonneau, D. (author), Lobino, M. (author), Jiang, P. (author), Natarajan, C.M. (author), Tanner, M.G. (author), Hadfield, R.H. (author), Dorenbos, S.N. (author), Zwiller, V. (author), Thompson, M.G. (author), O'Brien, J.L. (author), Bonneau, D. (author), Lobino, M. (author), Jiang, P. (author), Natarajan, C.M. (author), Tanner, M.G. (author), Hadfield, R.H. (author), Dorenbos, S.N. (author), Zwiller, V. (author), Thompson, M.G. (author), and O'Brien, J.L. (author)

Abstract

We demonstrate fast polarization and path control of photons at 1550 nm in lithium niobate waveguide devices using the electro-optic effect. We show heralded single photon state engineering, quantum interference, fast state preparation of two entangled photons, and feedback control of quantum interference. These results point the way to a single platform that will enable the integration of nonlinear single photon sources and fast reconfigurable circuits for future photonic quantum information science and technology., QN/Quantum Nanoscience, Applied Sciences

Published
2012
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13. Correlated photon-pair generation in a periodically poled MgO doped stoichiometric lithium tantalate reverse proton exchanged waveguide

Author

Lobino, M. (author), Marshall, G.D. (author), Xiong, C. (author), Clark, A.S. (author), Bonneau, D. (author), Natarajan, C.M. (author), Tanner, M.G. (author), Hadfield, R.H. (author), Dorenbos, S.N. (author), Zijlstra, T. (author), Zwiller, V. (author), Marangoni, M. (author), Ramponi, R. (author), Thompson, M.G. (author), Eggleton, B.J. (author), O'Brien, J.L. (author), Lobino, M. (author), Marshall, G.D. (author), Xiong, C. (author), Clark, A.S. (author), Bonneau, D. (author), Natarajan, C.M. (author), Tanner, M.G. (author), Hadfield, R.H. (author), Dorenbos, S.N. (author), Zijlstra, T. (author), Zwiller, V. (author), Marangoni, M. (author), Ramponi, R. (author), Thompson, M.G. (author), Eggleton, B.J. (author), and O'Brien, J.L. (author)

Abstract

We demonstrate photon-pair generation in a reverse proton exchanged waveguide fabricated on a periodically poled magnesium doped stoichiometric lithium tantalate substrate. Detected pairs are generated via a cascaded second order nonlinear process where a pump laser at wavelength of 1.55 ?m is first doubled in frequency by second harmonic generation and subsequently downconverted around the same spectral region. Pairs are detected at a rate of 42/s with a coincidence to accidental ratio of 0.7. This cascaded pair generation process is similar to four-wave-mixing where two pump photons annihilate and create a correlated photon pair., QN/Quantum Nanoscience, Applied Sciences

Published
2011
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14. Erratum: “Generation of correlated photon pairs in a chalcogenide As2S3 waveguide” [ Appl. Phys. Lett. 98, 051101 (2011) ]

Author

Xiong, C. (author), Marshall, G.D. (author), Peruzzo, A. (author), Lobino, M. (author), Clark, A.S. (author), Choi, D.Y. (author), Madden, S.J. (author), Natarajan, C.M. (author), Tanner, M.G. (author), Hadfield, R.H. (author), Dorenbos, S.N. (author), Zijlstra, T. (author), Zwiller, V. (author), Thompson, M.G. (author), Rarity, J.G. (author), Steel, M.J. (author), Luther-Davies, B. (author), Eggleton, B.J. (author), O'Brien, J.L. (author), Xiong, C. (author), Marshall, G.D. (author), Peruzzo, A. (author), Lobino, M. (author), Clark, A.S. (author), Choi, D.Y. (author), Madden, S.J. (author), Natarajan, C.M. (author), Tanner, M.G. (author), Hadfield, R.H. (author), Dorenbos, S.N. (author), Zijlstra, T. (author), Zwiller, V. (author), Thompson, M.G. (author), Rarity, J.G. (author), Steel, M.J. (author), Luther-Davies, B. (author), Eggleton, B.J. (author), and O'Brien, J.L. (author)

Abstract

QN/Quantum Nanoscience, Applied Sciences

Published
2011
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15. Generation of correlated photon pairs in a chalcogenide As2S3 waveguide

Author

Xiong, C. (author), Marshall, G.D. (author), Peruzzo, A. (author), Lobino, M. (author), Clark, A.S. (author), Choi, D.Y. (author), Madden, S.J. (author), Natarajan, C.M. (author), Tanner, M.G. (author), Hadfield, R.H. (author), Dorenbos, S.N. (author), Zijlstra, T. (author), Zwiller, V. (author), Thompson, M.G. (author), Rarity, J.G. (author), Steel, M.J. (author), Luther-Davies, B. (author), Eggleton, B.J. (author), O'Brien, J.L. (author), Xiong, C. (author), Marshall, G.D. (author), Peruzzo, A. (author), Lobino, M. (author), Clark, A.S. (author), Choi, D.Y. (author), Madden, S.J. (author), Natarajan, C.M. (author), Tanner, M.G. (author), Hadfield, R.H. (author), Dorenbos, S.N. (author), Zijlstra, T. (author), Zwiller, V. (author), Thompson, M.G. (author), Rarity, J.G. (author), Steel, M.J. (author), Luther-Davies, B. (author), Eggleton, B.J. (author), and O'Brien, J.L. (author)

Abstract

We demonstrate a 1550 nm correlated photon-pair source in an integrated glass platform—a chalcogenide As2S3 waveguide. A measured pair coincidence rate of 80?s?1 was achieved using 57 mW of continuous-wave pump. The coincidence to accidental ratio was shown to be limited by spontaneous Raman scattering effects that are expected to be mitigated by using a pulsed pump source., QN/Quantum Nanoscience, Applied Sciences

Published
2011
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23. Quantization and chiral edge state properties in nearly 3D quantum well structures

Author

Zhang, B., Brooks, J.S., Wang, Z., Perenboom, Jos, Simmons, J., Reno, J., Lumpkin, N., O'Brien, J.L., Clark, R., Zhang, B., Brooks, J.S., Wang, Z., Perenboom, Jos, Simmons, J., Reno, J., Lumpkin, N., O'Brien, J.L., and Clark, R.

Abstract

Contains fulltext : 112510.pdf (publisher's version ) (Closed access)

Published
1998

27. Construction of a silicon-based solid state quantum computer

Author

Dzurak, A.S., primary, Simmons, M.Y., additional, Hamilton, A.R., additional, Clark, R.G., additional, Brenner, R., additional, Buehler, T.M., additional, Curson, N.J., additional, Gauja, E., additional, McKinnon, R.P., additional, Macks, L.D., additional, Mitic, M., additional, O’brien, J.L., additional, Oberbeck, L., additional, Reilly, D.J., additional, Schofield, S.R., additional, and Stanley, F.E., additional

Published
2001
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31. Demonstration of an all-optical quantum controlled-NOT gate.

Author

O'Brien, J.L., Pryde, G.J., White, A.G., Ralph, T.C., and Branning, D.

Subjects
*QUANTUM computers, *GATEWAYS (Computer networks), *LOGIC devices
Abstract

The promise of tremendous computational power, coupled with the development of robust error-correcting schemes, has fuelled extensive efforts to build a quantum computer. The requirements for realizing such a device are confounding: scalable quantum bits (two-level quantum systems, or qubits) that can be well isolated from the environment, but also initialized, measured and made to undergo controllable interactions to implement a universal set of quantum logic gates. The usual set consists of single qubit rotations and a controlled-NOT (CNOT) gate, which flips the state of a target qubit conditional on the control qubit being in the state 1. Here we report an unambiguous experimental demonstration and comprehensive characterization of quantum CNOT operation in an optical system. We produce all four entangled Bell states as a function of only the input qubits' logical values, for a single operating condition of the gate. The gate is probabilistic (the qubits are destroyed upon failure), but with the addition of linear optical quantum non-demolition measurements, it is equivalent to the CNOT gate required for scalable all-optical quantum computation. [ABSTRACT FROM AUTHOR]

Published
2003
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36. Longitudinal fMRI in elderly reveals loss of hippocampal activation with clinical decline(e–Pub ahead of print)

Author

O'Brien, J.L., O'Keefe, K.M., LaViolette, P.S., DeLuca, A.N., Blacker, D., Dickerson, B.C., and Sperling, R.A.

Abstract

Previous cross-sectional fMRI studies in subjects with prodromal Alzheimer disease (AD) have reported variable results, ranging from hypoactivation, similar to patients with AD, to paradoxically increased activation or hyperactivation compared to cognitively normal older individuals. We have hypothesized that subjects in early phases of prodromal AD may experience a period of hippocampal hyperactivation, followed by loss of hippocampal activation as the disease progresses.

Published
2010
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42. The atomic fabrication of a silicon based quantum computer

Author

Simmons, M.Y., primary, Schofield, S.R., additional, O'Brien, J.L., additional, Curson, N.J., additional, Clark, R.G., additional, Buehler, T.M., additional, McKinnon, R.P., additional, Brenner, R., additional, Reilly, D.J., additional, Dzurak, A.S., additional, and Hamilton, A.R., additional

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46. New photonic components for quantum information science.

Author

Politi, A., Matthews, J.C.F., Laing, A., Peruzzo, A., Poulios, K., Meinecke, J., Bonneau, D., Shadbolt, P., Kalasuwan, P., Xiao-Qi Zhou, Verde, M.R., Lobino, M., Rudolph, T., Rarity, J.G., Thompson, M.G., and O'Brien, J.L.

Published
2011

48. Integrated quantum information science with photons.

Author

Politi, A., Matthews, J.C.F., Laing, A., Peruzzo, A., Kalasuwan, P., Mian Zhang, Xiao-Qi Zhou, Rodas, M., Cryan, M.J., Rarity, J.G., Stefanov, A., Siyuan Yu, Thompson, M.G., and O'Brien, J.L.

Published
2009

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