News
Doctoral Thesis: Nino Walenta
Congratulations to Dr. Nino Walenta from our group, who defended his doctoral thesis this January. His research topic focused on the practical implementation of Quantum Key Distribution. His thesis is available from our website.
When Science meets Science-Fiction: Open lecture by Prof. Nicolas Gisin
This February, Professor Nicolas Gisin gave an open lecture at the University of Geneva, focusing on some of the extraordinary topics in his research. Starting off by talking about the implications of Newton's theory of universal gravitation, he led the audience to discover the fascinating phenomenon of quantum teleportation and the concept of non-locality. The lecture is now available for public viewing in French on the University of Geneva's Media Server.
Quantum Cryptography: Does it have a future? Classic cryptology isn't budging, but all depends on QKD.
Here is an excellent article written by Chris Lee on the Ars Technica website. It provides an overview and explanation of Quantum Cryptography for the general public, starting with the motivation for this technology; namely Quantum Computing, which could provide an efficient way of hacking classical encryption methods in the future. An interview with Professor Nicolas Gisin outlines the corresponding research work carried out in our group. In order to aid understanding, it includes a nice video explaining one version of Quantum Cryptography protocols, the so called BB84 protocol.
Quantum networks: A future without long memories?
In our article published in the November issue of Nature Photonics, Nicolas Sangouard discusses a recent proposal for a quantum communication protocol without quantum memories, which could be an alternative approach for distributing quantum information over long distances. However, it is not without its own challenges, which are discussed and compared to the current work on quantum repeaters.
Quantum Science in Switzerland
Our group is part of a National Center of Competence in Research project, namely 'QSIT - Quantum Science and Technology', which comprises of 34 research groups from different institutions from all over Switzerland. A key goal of this project is to facilitate strong interactions between these groups. This video gives an introduction to the various topics studied and more information can be found on the NCCR-QSIT website.
Superactivation of quantum nonlocality
In a recent Viewpoint article on the APS Physics website, Professor Nicolas Brunner and Professor Nicolas Gisin discuss a recent finding that the combination of a number of local states can give rise to nonlocality. This is yet another wonderfully counterintuitive phenomenon of quantum theory: as though one can get something out of nothing!
Choose one: non-locality or superluminal signalling
Quantum theory has always been a controversial and bizarre physical
theory. In our newly published letter [1] in Nature Physics, we make
an important step towards understanding the origin of quantum
nonlocality [2] — one of the strangest features offered by quantum
theory — through a general family of physical models that could
seemingly explain all possible correlations. Specifically, these
models make use of what's called local common cause and finite-speed
causal influences that travel at superluminal speed to produce
correlations between measurement outcomes of physical systems. Earlier
attempts [3,4] to test the plausibility of such models require
extremely well synchronized measurements but such approach, in
practice, may only be able to put lower bounds on the speed of causal
influences.
NJP Highlight 2011! Experimental amplification of an entangled photon
Our paper discussing the possible consequences of ignoring the detection loophole whilst trying to detect micro-macro entanglement has been included in the New Journal of Physics: Highlights of 2011.
Radio Interview - Qu'est-ce que la téléportation quantique?
In an interview at Radio France Internationale Professor Nicolas Gisin discusses his recently published book L'impensable hasard - Non-localité, téléportation et autres merveilles quantiques:
“Explication du monde à très petite échelle, monde peuplé d'atomes et de photons, la physique quantique n'est pas avare de propriétés singulières. A notre échelle, la supraconductivité, les lasers et l'effet tunnel résultent de phénomènes quantiques. Mais cette science a aussi des implications plus fondamentales, qui constituent de véritables défis à la logique ordinaire. La notion d'“intrication”, en particulier, explorée depuis une trentaine d'années, mène à l'existence, très contre-intuitive, d'un hasard ubiquitaire, capable de se manifester simultanément en plusieurs endroits de notre univers…
Cette stupéfiante “non-localité” n'est pas une abstraction gratuite ou un jeu de l'esprit ; elle a des applications bien concrètes en cryptographie, pour la protection des données financières et médicales, et a permis la démonstration d'une “téléportation quantique” dont les auteurs de science-fiction les plus imaginatifs ont du mal à entrevoir les infinies possibilités.
A l'opposé de la littérature ordinaire sur le sujet, ce petit livre ne tente pas de contourner les réelles difficultés conceptuelles imposées par la physique quantique. De “jeu de Bell” en expériences d'intrication quantique, il mène vers une solide compréhension d'un des domaines les plus fascinants de la physique actuelle.
Physicien théoricien, directeur du département de physique appliquée de l'Université de Genève, Nicolas Gisin est un pionnier de la cryptographie, de la téléportation et de l'informatique quantiques. Il est co-fondateur de la société id Quantique, leader mondial en cryptographie quantique. Il a reçu en 2009 le premier prix John Stewart Bell.”
Listen to the interview in two parts here:
Part 1:
Part 2:
Solid-state quantum memory for polarization qubits
Our work on the storage of polarization qubits encoded on heralded single photons has just been published in Physical Review Letters. In the same issue, two other groups report similar results, putting into evidence the importance of the results. Additionally, Physics has dedicated a synopsis to the three articles, and also physicsworld.com gives an overview.
