FP7
Bayesian quantum frequency estimation in presence of collective dephasing
Tue, 2016-05-10 10:34 - Michal JachuraNew J. Phys. 16, 113002 (2014)
We advocate a Bayesian approach to optimal quantum frequency estimation—an important issue for future quantum enhanced atomic clock operation. The approach provides a clear insight into the interplay between decoherence and the extent of prior knowledge in determining the optimal interrogation times and optimal estimation strategies.
Superfluid density and quasi-long-range order in the one-dimensional disordered Bose-Hubbard model
Thu, 2016-03-03 10:47 - Mattia GiardiniJournal reference: New J. Phys. 18, 015015 (2016)
DOI: 10.1088/1367-2630/18/1/015015
Abstract:
PICQUE Bristol Young Scientists Conference on Quantum Information with Photons
Tue, 2016-01-26 17:22 - Giuliana Pensa, University of Rome La SapienzaBroadband noise-free optical quantum memory with neutral nitrogen-vacancy centers in diamond
Tue, 2015-06-02 01:48 - Josh NunnIOPEXPORT_BIB.bib
IOPEXPORT_BIB.bib
- PhysRevB.91.205108
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Broadband noise-free optical quantum memory with neutral nitrogen-vacancy centers in diamond
E. Poem and C. Weinzetl and J. Klatzow and K. T. Kaczmarek and J. H. D. Munns and T. F. M. Champion and D. J. Saunders and J. Nunn and I. A. Walmsley
Phys. Rev. B
91
205108
(2015)
http://link.aps.org/doi/10.1103/PhysRevB.91.205108
http://dx.doi.org/10.1103/PhysRevB.91.205108
It is proposed that the ground-state manifold of the neutral nitrogen-vacancy center in diamond could be used as a quantum two-level system in a solid-state-based implementation of a broadband noise-free quantum optical memory.
Interfacing GHz-bandwidth heralded single photons with a warm vapour Raman memory
Tue, 2015-06-02 01:44 - Josh NunnIOPEXPORT_BIB.bib
IOPEXPORT_BIB.bib
- 1367-2630-17-4-043006
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Interfacing GHz-bandwidth heralded single photons with a warm vapour Raman memory
P. S. Michelberger and T. F. M. Champion and M. R. Sprague and K. T. Kaczmarek and M. Barbieri and X. M. Jin and D. G. England and W. S. Kolthammer and D. J. Saunders and J. Nunn and I. A. Walmsley
New Journal of Physics
17
043006
(2015)
http://stacks.iop.org/1367-2630/17/i=4/a=043006Broadband quantum memories, used as temporal multiplexers, are a key component in photonic quantum information processing, as they make repeat-until-success strategies scalable. We demonstrate a prototype system, operating on-demand, by interfacing a warm vapour, high time-bandwidth-product Raman memory with a travelling wave spontaneous parametric down-conversion source. We store single photons and observe a clear influence of the input photon statistics on the retrieved light, which we find currently to be limited by noise. We develop a theoretical model that identifies four-wave mixing as the sole important noise source and point towards practical solutions for noise-free operation.
Tomography of photon-number resolving continuous-output detectors
Tue, 2015-06-02 01:40 - Josh NunnStrain-optic active control for quantum integrated photonics
Tue, 2015-06-02 01:38 - Josh NunnP. Humphreys, B. Metcalf, J. Spring, M. Moore, P. Salter, M. Booth, W. Steven Kolthammer, and I. Walmsley, "Strain-optic active control for quantum integrated photonics," Opt. Express 22, 21719-21726 (2014).
We present a practical method for active phase control on a photonic chip that has immediate applications in quantum photonics. Our approach uses strain-optic modification of the refractive index of individual waveguides, effected by a millimeter-scale mechanical actuator.
Joint estimation of phase and phase diffusion for quantum metrology
Tue, 2015-06-02 01:34 - Josh Nunn- cite-key
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Joint estimation of phase and phase diffusion for quantum metrology
M. D. Vidrighin and G. Donati and M. G. Genoni and X.-M. Jin and W. S. Kolthammer and M. S. Kim and A. Datta and M. Barbieri and I. A. Walmsley
Nat Commun
5
(2014)
http://dx.doi.org/10.1038/ncomms4532Phase estimation, at the heart of many quantum metrology and communication schemes, can be strongly affected by noise, whose amplitude may not be known, or might be subject to drift. Here we investigate the joint estimation of a phase shift and the amplitude of phase diffusion at the quantum limit. For several relevant instances, this multiparameter estimation problem can be effectively reshaped as a two-dimensional Hilbert space model, encompassing the description of an interferometer phase probed with relevant quantum states—split single-photons, coherent states or N00N states. For these cases, we obtain a trade-off bound on the statistical variances for the joint estimation of phase and phase diffusion, as well as optimum measurement schemes. We use this bound to quantify the effectiveness of an actual experimental set-up for joint parameter estimation for polarimetry. We conclude by discussing the form of the trade-off relations for more general states and measurements.
Phase estimation, at the heart of many quantum metrology and communication schemes, can be strongly affected by noise, whose amplitude may not be known, or might be subject to drift. Here we investigate the joint estimation of a phase shift and the amplitude of phase diffusion at the quantum limit.
Continuous-Variable Quantum Computing in Optical Time-Frequency Modes Using Quantum Memories
Tue, 2015-06-02 01:31 - Josh Nunn- PhysRevLett.113.130502
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Continuous-Variable Quantum Computing in Optical Time-Frequency Modes Using Quantum Memories
P. C. Humphreys and W. S. Kolthammer and J. Nunn and M. Barbieri and A. Datta and I. A. Walmsley
Phys. Rev. Lett.
113
130502
(2014)
http://link.aps.org/doi/10.1103/PhysRevLett.113.130502
http://dx.doi.org/10.1103/PhysRevLett.113.130502
We develop a scheme for time-frequency encoded continuous-variable cluster-state quantum computing using quantum memories. In particular, we propose a method to produce, manipulate, and measure two-dimensional cluster states in a single spatial mode by exploiting the intrinsic time-frequency selectivity of Raman quantum memories.
Quantum teleportation on a photonic chip
Tue, 2015-06-02 01:25 - Josh Nunn- cite-key
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Quantum teleportation on a photonic chip
B. J. Metcalf and J. B. Spring and P. C. Humphreys and N. Thomas-Peter and M. Barbieri and W. S. Kolthammer and X.-M. Jin and N. K. Langford and D. Kundys and J. C. Gates and B. J. Smith and P. G. R. Smith and I. A. Walmsley
Nat Photon
8
770--774
(2014)
http://dx.doi.org/10.1038/nphoton.2014.217
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