Characterizing the nonlocal correlations of particles that never interacted (2009)
Branciard, Cyril, Gisin, Nicolas, Pironio, Stefano
Quantum systems that have never interacted can become nonlocally correlated through a process called entanglement swapping. To characterize nonlocality in this context, we introduce local models...
The local content of bipartite qubit correlations (2009)
Branciard, Cyril, Gisin, Nicolas, Scarani, Valerio
One of the last open problems concerning two qubits in a pure state is to find the exact local content of their correlation, in the sense of Elitzur, Popescu and Rohrlich (EPR2) [Phys. Lett. A 162,...
Simulation of equatorial von Neumann measurements on GHZ states using nonlocal resources (2009)
Bancal, Jean-Daniel, Branciard, Cyril, Gisin, Nicolas
Reproducing with elementary resources the correlations that arise when a quantum system is measured (quantum state simulation), allows one to get insight on the operational and computational power of...
Quantifying multipartite nonlocality (2009)
Bancal, Jean-Daniel, Branciard, Cyril, Gisin, Nicolas, Pironio, Stefano
The nonlocal correlations of multipartite entangled states can be reproduced by a classical model if sufficiently many parties join together or if sufficiently many parties broadcast their...
Quantum experiments with human eyes as detectors based on cloning via stimulated emission (2009)
Sekatski, Pavel, Brunner, Nicolas, Branciard, Cyril, Gisin, Nicolas, Simon, Christoph
We show theoretically that the multi-photon states obtained by cloning single-photon qubits via stimulated emission can be distinguished with the naked human eye with high efficiency and fidelity....
Testing a Bell inequality in multi-pair scenarios (2008)
Bancal, Jean-Daniel, Branciard, Cyril, Brunner, Nicolas, Gisin, Nicolas, Popescu, Sandu, Simon, Christoph
To date, most efforts to demonstrate quantum nonlocality have concentrated on systems of two (or very few) particles. It is however difficult in many experiments to address individual particles,...
Romain Alléaume, Jan Bouda, Cyril Branciard, Thierry Debuisschert, Nicolas Gisin, Mark Godfrey, ...
Version: 5.1 Document history: During the first year of the SECOQC project [1], Philippe Grangier initiated an internal debate regarding the “comparative advantages ” of quantum key distribution...
Can one see entanglement ? (2008)
Brunner, Nicolas, Branciard, Cyril, Gisin, Nicolas
The human eye can detect optical signals containing only a few photons. We investigate the possibility to demonstrate entanglement with such biological detectors. While one person could not detect...
A simple approach to test Leggett's model of nonlocal quantum correlations (2008)
Branciard, Cyril, Brunner, Nicolas, Gisin, Nicolas, Kurtsiefer, Christian, Lamas-Linares, Antia, Ling, Alexander, ...
We present new inequalities for testing Leggett's model [Found. Phys. 33, 1469 (2003)] of non-local quantum correlations. Remarkably these inequalities can be derived in a very simple way, assuming...
Branciard, Cyril, Gisin, Nicolas, Scarani, Valerio
The Differential-Phase-Shift (DPS) and the Coherent-One-Way (COW) are among the most practical protocols for quantum cryptography, and are therefore the object of fast-paced experimental...
Experimental Falsification of Leggett's Non-Local Variable Model (2007)
Branciard, Cyril, Ling, Alexander, Gisin, Nicolas, Kurtsiefer, Christian, Lamas-Linares, Antia, Scarani, Valerio
Bell's theorem guarantees that no model based on local variables can reproduce quantum correlations. Also some models based on non-local variables, if subject to apparently "reasonable" constraints,...
SECOQC White Paper on Quantum Key Distribution and Cryptography (2007)
Alleaume, Romain, Bouda, Jan, Branciard, Cyril, Debuisschert, Thierry, Dianati, Mehrdad, Gisin, Nicolas, ...
The SECOQC White Paper on Quantum Key Distribution and Cryptography is the outcome on a thorough consultation and discussion among the participants of the European project SECOQC (www.secoqc.net)....
Kraus, Barbara, Branciard, Cyril, Renner, Renato
We apply the techniques introduced in [Kraus et. al., Phys. Rev. Lett. 95, 080501, 2005] to prove security of quantum key distribution (QKD) schemes using two-way classical post-processing as well as...
Branciard, Cyril, Gisin, Nicolas, Lutkenhaus, Norbert, Scarani, Valerio
This is a study of the security of the Coherent One-Way (COW) protocol for quantum cryptography, proposed recently as a simple and fast experimental scheme. In the zero-error regime, the eavesdropper...
Security of two quantum cryptography protocols using the same four qubit states (2005)
Branciard, Cyril, Gisin, Nicolas, Kraus, Barbara, Scarani, Valerio
The first quantum cryptography protocol, proposed by Bennett and Brassard in 1984 (BB84), has been widely studied in the last years. This protocol uses four states (more precisely, two complementary...