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Institution

ICFO – The Institute of Photonic Sciences

FacilityBarcelona, Spain
About: ICFO – The Institute of Photonic Sciences is a facility organization based out in Barcelona, Spain. It is known for research contribution in the topics: Quantum & Quantum entanglement. The organization has 872 authors who have published 1965 publications receiving 56273 citations.


Papers
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Journal ArticleDOI
21 Oct 2015-Nature
TL;DR: The data imply statistically significant rejection of the local-realist null hypothesis and could be used for testing less-conventional theories, and for implementing device-independent quantum-secure communication and randomness certification.
Abstract: More than 50 years ago, John Bell proved that no theory of nature that obeys locality and realism can reproduce all the predictions of quantum theory: in any local-realist theory, the correlations between outcomes of measurements on distant particles satisfy an inequality that can be violated if the particles are entangled. Numerous Bell inequality tests have been reported; however, all experiments reported so far required additional assumptions to obtain a contradiction with local realism, resulting in 'loopholes'. Here we report a Bell experiment that is free of any such additional assumption and thus directly tests the principles underlying Bell's inequality. We use an event-ready scheme that enables the generation of robust entanglement between distant electron spins (estimated state fidelity of 0.92 ± 0.03). Efficient spin read-out avoids the fair-sampling assumption (detection loophole), while the use of fast random-basis selection and spin read-out combined with a spatial separation of 1.3 kilometres ensure the required locality conditions. We performed 245 trials that tested the CHSH-Bell inequality S ≤ 2 and found S = 2.42 ± 0.20 (where S quantifies the correlation between measurement outcomes). A null-hypothesis test yields a probability of at most P = 0.039 that a local-realist model for space-like separated sites could produce data with a violation at least as large as we observe, even when allowing for memory in the devices. Our data hence imply statistically significant rejection of the local-realist null hypothesis. This conclusion may be further consolidated in future experiments; for instance, reaching a value of P = 0.001 would require approximately 700 trials for an observed S = 2.4. With improvements, our experiment could be used for testing less-conventional theories, and for implementing device-independent quantum-secure communication and randomness certification.

2,397 citations

Journal ArticleDOI
13 Sep 2017-Nature
TL;DR: The field of quantum machine learning explores how to devise and implement quantum software that could enable machine learning that is faster than that of classical computers.
Abstract: Recent progress implies that a crossover between machine learning and quantum information processing benefits both fields. Traditional machine learning has dramatically improved the benchmarking an ...

2,162 citations

Journal ArticleDOI
TL;DR: The theoretical and experimental status quo of this very active field of quantum repeater protocols is reviewed, and the potentials of different approaches are compared quantitatively, with a focus on the most immediate goal of outperforming the direct transmission of photons.
Abstract: The distribution of quantum states over long distances is limited by photon loss. Straightforward amplification as in classical telecommunications is not an option in quantum communication because of the no-cloning theorem. This problem could be overcome by implementing quantum repeater protocols, which create long-distance entanglement from shorter-distance entanglement via entanglement swapping. Such protocols require the capacity to create entanglement in a heralded fashion, to store it in quantum memories, and to swap it. One attractive general strategy for realizing quantum repeaters is based on the use of atomic ensembles as quantum memories, in combination with linear optical techniques and photon counting to perform all required operations. Here the theoretical and experimental status quo of this very active field are reviewed. The potentials of different approaches are compared quantitatively, with a focus on the most immediate goal of outperforming the direct transmission of photons.

1,603 citations

Journal ArticleDOI
TL;DR: A Bell test is reported that closes the most significant of loopholes that provide loopholes for a local realist explanation of quantum mechanics, using a well-optimized source of entangled photons, rapid setting generation, and highly efficient superconducting detectors.
Abstract: Local realism is the worldview in which physical properties of objects exist independently of measurement and where physical influences cannot travel faster than the speed of light. Bell's theorem states that this worldview is incompatible with the predictions of quantum mechanics, as is expressed in Bell's inequalities. Previous experiments convincingly supported the quantum predictions. Yet, every experiment requires assumptions that provide loopholes for a local realist explanation. Here, we report a Bell test that closes the most significant of these loopholes simultaneously. Using a well-optimized source of entangled photons, rapid setting generation, and highly efficient superconducting detectors, we observe a violation of a Bell inequality with high statistical significance. The purely statistical probability of our results to occur under local realism does not exceed 3.74×10^{-31}, corresponding to an 11.5 standard deviation effect.

1,262 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a loophole-free violation of local realism using entangled photon pairs, ensuring that all relevant events in their Bell test are spacelike separated by placing the parties far enough apart and by using fast random number generators and high-speed polarization measurements.
Abstract: We present a loophole-free violation of local realism using entangled photon pairs. We ensure that all relevant events in our Bell test are spacelike separated by placing the parties far enough apart and by using fast random number generators and high-speed polarization measurements. A high-quality polarization-entangled source of photons, combined with high-efficiency, low-noise, single-photon detectors, allows us to make measurements without requiring any fair-sampling assumptions. Using a hypothesis test, we compute p values as small as 5.9×10^{-9} for our Bell violation while maintaining the spacelike separation of our events. We estimate the degree to which a local realistic system could predict our measurement choices. Accounting for this predictability, our smallest adjusted p value is 2.3×10^{-7}. We therefore reject the hypothesis that local realism governs our experiment.

1,201 citations


Authors

Showing all 928 results

NameH-indexPapersCitations
Maciej Lewenstein10493147362
F. Javier García de Abajo7535130221
Antonio Acín7232419984
Frank H. L. Koppens6923932754
Romain Quidant6824818262
Leszek Kaczmarek6730215985
Sefaattin Tongay6525420628
Zhipei Sun6527027030
Lluis Torner6456617978
Georg Heinze6335416391
Yaroslav V. Kartashov5448711174
Francesco Ricci5429515492
Gerasimos Konstantatos5316019627
Niek F. van Hulst5317812400
Turgut Durduran5328910525
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
20239
202261
2021269
2020308
2019287
2018285