Annuaire du Collège de France 2014-2015
Two conferences
Plan
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Conférences prononcées les 25 mars et 1er avril 2015 (invitation sur proposition du Pr Serge Haroche).
Texte intégral
Quantum imaging and the role of information
1Entangled quantum states provide novel ways for nonlocal imaging. Well known is ghost imaging where the image appears for a photon entangled with the one which interacts with the object. Most recently, it was seen that exploiting just the product state nature of photon pairs, one can obtain imaging where the photon interacting with the object does not even have to be detected.
2In this lecture, I will discuss particularly the role of information in these imaging methods, and it will be shown that in some experiments, the photon interacting with the sample has to be detected in order to destroy path information and make imaging possible. In the more recent case, this is not necessary at all. It turns out that the phenomenon of “quantum imaging with undetected photons” exploits the fact that the phase of a product state cannot be localized. I will present practical applications and an outlook for future experiments.
Quantum entanglement in higher dimensions
3Most fundamental experiments in quantum mechanics have been performed with qubits, i.e. in rather low dimensional Hilbert spaces. Various experimental techniques have recently opened up discrete higher dimensions for experiments. These are particularly multi-mode interference and photon states with more complex wavefronts, like orbital angular momentum (OAM) states.
4In the talk, I will present some recent results focusing on OAM states and on verifications of entanglement in very high dimensions. So far, entanglement of quantum states with quantum numbers around 1,000 and of superposition in more than 100-dimensional Hilbert space have been realized. This may shed interesting light on the question of the quantum-classical transition. I will also discuss recent experiments for using some of these states in quantum communication with higher alphabets.
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Référence papier
Annuaire du Collège de France 2014-2015. Résumé des cours et travaux 115e année, Paris, Collège de France, novembre 2016, p. 885-886. ISBN 978-2-7226-0453-7
Référence électronique
Anton Zeilinger, « Two conferences », L’annuaire du Collège de France [En ligne], 115 | 2016, mis en ligne le 22 juin 2018, consulté le 24 janvier 2021. URL : http://journals.openedition.org/annuaire-cdf/12702 ; DOI : https://doi.org/10.4000/annuaire-cdf.12702
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