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| Author |
Prevedel, Robert; Hamel, Deny R.; Colbeck, Roger; Fisher, Kent; Resch, Kevin J. |
Title  |
Experimental investigation of the uncertainty principle in the presence of quantum memory and its application to witnessing entanglement |
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Journal Article |
| Year |
2011 |
Publication |
Nature Physics |
Abbreviated Journal |
Nat. Phys. |
| Volume |
7 |
Issue |
10 |
Pages |
757-761 |
| Keywords |
fromIPMRAS |
| Abstract |
Heisenberg's uncertainty principle provides a fundamental limitation on the ability of an observer holding classical information to predict the outcome when one of two measurements is performed on a quantum system. However, an observer with access to a particle (stored in a quantum memory) which is entangled with the system generally has a reduced uncertainty: indeed, if the particle and system are maximally entangled, the observer can perfectly predict the outcome of whichever measurement is chosen. This effect has recently been quantified in a new entropic uncertainty relation. Here we experimentally investigate this relation, showing its effectiveness as an efficient entanglement witness. We use entangled photon pairs, an optical delay line serving as a simple quantum memory and fast, active feed-forward. Our results quantitatively agree with the new uncertainty relation. Our technique acts as a witness for almost all entangled states in our experiment as we obtain lower uncertainties than would be possible without the entangled particle. |
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821 |
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Dada, Adetunmise C.; Leach, Jonathan; Buller, Gerald S.; Padgett, Miles J.; Andersson, Erika |
| Title |
Experimental high-dimensional two-photon entanglement and violations of generalized Bell inequalities |
Type |
Journal Article |
| Year |
2011 |
Publication |
Nature Physics |
Abbreviated Journal |
Nat. Phys. |
| Volume |
7 |
Issue |
9 |
Pages |
677-680 |
| Keywords |
fromIPMRAS |
| Abstract |
Quantum entanglement plays a vital role in many quantum-information and communication tasks. Entangled states of higher-dimensional systems are of great interest owing to the extended possibilities they provide. For example, they enable the realization of new types of quantum information scheme that can offer higher-information-density coding and greater resilience to errors than can be achieved with entangled two-dimensional systems (see ref. and references therein). Closing the detection loophole in Bell test experiments is also more experimentally feasible when higher-dimensional entangled systems are used. We have measured previously untested correlations between two photons to experimentally demonstrate high-dimensional entangled states. We obtain violations of Bell-type inequalities generalized to d-dimensional systems up to d=12. Furthermore, the violations are strong enough to indicate genuine 11-dimensional entanglement. Our experiments use photons entangled in orbital angular momentum, generated through spontaneous parametric down-conversion, and manipulated using computer-controlled holograms. |
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RPLAB @ gujma @ |
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828 |
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Feresten, Nancy Laties; Thornton, Jennifer A.; Emmett, Jennifer; Lamichhane, Priyanka; Epstein, Lori; Kiesow, Annette; Olesin, Kate; Hill, Grace (eds) |
| Title |
Everything: Rocks and Minerals |
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Book Whole |
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2011 |
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Nat. Geogr. Partners |
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1-64 |
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Feresten, Nancy Laties; Thornton, Jennifer A.; Emmett, Jennifer; Lamichhane, Priyanka; Epstein, Lori; Kiesow, Annette; Olesin, Kate; Hill, Grace |
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1146 |
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Beck, M.; Klammer, M.; Lang, S.; Leiderer, P.; Kabanov, V. V.; Gol'tsman, G. N.; Demsar, J. |
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Energy-gap dynamics of superconducting NbN thin films studied by time-resolved terahertz spectroscopy |
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Journal Article |
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2011 |
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Phys. Rev. Lett. |
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Phys. Rev. Lett. |
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107 |
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17 |
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4 |
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NbN thin film, energy gap dynamics |
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Using time-domain terahertz spectroscopy we performed direct studies of the photoinduced suppression and recovery of the superconducting gap in a conventional BCS superconductor NbN. Both processes are found to be strongly temperature and excitation density dependent. The analysis of the data with the established phenomenological Rothwarf-Taylor model enabled us to determine the bare quasiparticle recombination rate, the Cooper pair-breaking rate and the electron-phonon coupling constant, λ=1.1±0.1, which is in excellent agreement with theoretical estimates. |
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RPLAB @ gujma @ |
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641 |
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Beck, M.; Klammer, M.; Lang, S.; Leiderer, P.; Kabanov, V. V.; Gol’tsman, G. N.; Demsar, J. |
| Title |
Energy-gap dynamics of superconducting NbN thin films studied by time-resolved terahertz spectroscopy |
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Miscellaneous |
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2011 |
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arXiv |
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NbN thin film, energy gap dynamics |
| Abstract |
Using time-domain Terahertz spectroscopy we performed direct studies of the photoinduced suppression and recovery of the superconducting gap in a conventional BCS superconductor NbN. Both processes are found to be strongly temperature and excitation density dependent. The analysis of the data with the established phenomenological Rothwarf-Taylor model enabled us to determine the bare quasiparticle recombination rate, the Cooper pair-breaking rate and the electron-phonon coupling constant, \lambda = 1.1 +/- 0.1, which is in excellent agreement with theoretical estimates. |
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Duplicated as 641 |
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1388 |
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