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...
Closing the detection loophole in Bell experiments using qudits (2009)
Vertesi, Tamas, Pironio, Stefano, Brunner, Nicolas
We show that the detection efficiencies required for closing the detection loophole in Bell tests can be significantly lowered using quantum systems of dimension larger than two. We introduce a...
Convergent relaxations of polynomial optimization problems with non-commuting variables (2009)
Pironio, Stefano, Navascues, Miguel, Acin, Antonio
We consider optimization problems with polynomial inequality constraints in non-commuting variables. These non-commuting variables are viewed as operators acting on a Hilbert space whose dimension is...
Device-independent quantum key distribution secure against collective attacks (2009)
Pironio, Stefano, Acin, Antonio, Brunner, Nicolas, Gisin, Nicolas, Massar, Serge, Scarani, Valerio
Device-independent quantum key distribution (DIQKD) represents a relaxation of the security assumptions made in usual quantum key distribution (QKD). As in usual QKD, the security of DIQKD follows...
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...
Navascues, Miguel, Pironio, Stefano, Acin, Antonio
We are interested in the problem of characterizing the correlations that arise when performing local measurements on separate quantum systems. In a previous work [Phys. Rev. Lett. 98, 010401 (2007)],...
Testing the Hilbert space dimension (2008)
Brunner, Nicolas, Pironio, Stefano, Acin, Antonio, Gisin, Nicolas, Methot, Andre Allan, Scarani, Valerio
Given a set of correlations originating from measurements on a quantum state of unknown Hilbert space dimension, what is the minimal dimension d necessary to describes such correlations? We introduce...
Noise robustness of the nonlocality of entangled quantum states (2007)
Almeida, Mafalda L., Pironio, Stefano, Barrett, Jonathan, Toth, Geza, Acin, Antonio
We study the nonlocal properties of states resulting from the mixture of an arbitrary entangled state rho of two d-dimensional systems and completely depolarized noise, with respective weights p and...
Device-independent security of quantum cryptography against collective attacks (2007)
Acin, Antonio, Brunner, Nicolas, Gisin, Nicolas, Massar, Serge, Pironio, Stefano, Scarani, Valerio
We present the optimal collective attack on a Quantum Key Distribution (QKD) protocol in the "device-independent" security scenario, where no assumptions are made about the way the QKD devices work...
Modeling Pauli measurements on graph states with nearest-neighbor classical communication (2007)
Barrett, Jonathan, Caves, Carlton M., Eastin, Bryan, Elliott, Matthew B., Pironio, Stefano
We propose a communication-assisted local-hidden-variable model that yields the correct outcome for the measurement of any product of Pauli operators on an arbitrary graph state, i.e., that yields...
Maximally Nonlocal and Monogamous Quantum Correlations (2006)
Barrett, Jonathan, Kent, Adrian, Pironio, Stefano
We introduce a version of the chained Bell inequality for an arbitrary number of measurement outcomes and use it to give a simple proof that the maximally entangled state of two d-dimensional quantum...
Bounding the set of quantum correlations (2006)
Navascues, Miguel, Pironio, Stefano, Acin, Antonio
We introduce a hierarchy of conditions necessarily satisfied by any distribution P(ab) representing the probabilities for two separate observers to obtain outcomes a and b when making local...
Efficient quantum key distribution secure against no-signalling eavesdroppers (2006)
Acin, Antonio, Massar, Serge, Pironio, Stefano
By carrying out measurements on entangled states, two parties can generate a secret key which is secure not only against an eavesdropper bound by the laws of quantum mechanics, but also against a...
Maximally Non-Local and Monogamous Quantum Correlations (2006)
Barrett, Jonathan, Kent, Adrian, Pironio, Stefano
We introduce a version of the chained Bell inequality for an arbitrary number of measurement outcomes, and use it to give a simple proof that the maximally entangled state of two d dimensional...
Modeling Pauli measurements on graph states with nearest-neighbor classical communication (2006)
Barrett, Jonathan, Caves, Carlton M., Eastin, Bryan, Elliott, Matthew B., Pironio, Stefano
We propose a communication-assisted local-hidden-variable model that yields the correct outcome for the measurement of any product of Pauli operators on an arbitrary graph state, i.e., that yields...
Popescu-Rohrlich Correlations as a Unit of Nonlocality (2005)
Barrett, Jonathan, Pironio, Stefano
A set of nonlocal correlations that have come to be known as a Popescu-Rohrlich (PR) box suggest themselves as a natural unit of nonlocality, much as a singlet is a natural unit of entanglement. We...
Popescu-Rohrlich correlations as a unit of nonlocality (2005)
Barrett, Jonathan, Pironio, Stefano
A set of nonlocal correlations that have come to be known as a PR box suggest themselves as a natural unit of nonlocality, much as a singlet is a natural unit of entanglement. We present two results...
Lifting Bell inequalities (2005)
A Bell inequality defined for a specific experimental configuration can always be extended to a situation involving more observers, measurement settings, or measurement outcomes. In this article,...
Lifting Bell inequalities (2005)
A Bell inequality defined for a specific experimental configuration can always be extended to a situation involving more observers, measurement settings or measurement outcomes. In this article, such...
Aspects of Quantum Non-locality (2004)
La mécanique quantique prédit l'existence de corrélations entre particules distantes qui ne peuvent s'expliquer dans le cadre des théories réalistes locales. Suite au développement récent de...
Aspects of Quantum Non-locality (2004)
La mécanique quantique prédit l'existence de corrélations entre particules distantes qui ne peuvent s'expliquer dans le cadre des théories réalistes locales. Suite au développement récent de...
Aspects of Quantum Non-locality (2004)
La mécanique quantique prédit l'existence de corrélations entre particules distantes qui ne peuvent s'expliquer dans le cadre des théories réalistes locales. Suite au développement récent de...
Aspects of Quantum Non-locality (2004)
La mécanique quantique prédit l'existence de corrélations entre particules distantes qui ne peuvent s'expliquer dans le cadre des théories réalistes locales. Suite au développement récent de...
Non-local correlations as an information theoretic resource (2004)
Barrett, Jonathan, Linden, Noah, Massar, Serge, Pironio, Stefano, Popescu, Sandu, Roberts, David
It is well known that measurements performed on spatially separated entangled quantum systems can give rise to correlations that are non-local, in the sense that a Bell inequality is violated. They...
To reproduce in a local hidden variables theory correlations that violate Bell inequalities, communication must occur between the parties. We show that the amount of violation of a Bell inequality...
Violation of local realism vs detection efficiency (2002)
Massar, Serge, Pironio, Stefano
We put bounds on the minimum detection efficiency necessary to violate local realism in Bell experiments. These bounds depends of simple parameters like the number of measurement settings or the...
A Zoology of Bell inequalities resistant to detector inefficiency (2002)
Massar, Serge, Pironio, Stefano, Roland, Jeremie, Gisin, Bernard
We derive both numerically and analytically Bell inequalities and quantum measurements that present enhanced resistance to detector inefficiency. In particular we describe several Bell inequalities...
Multipartite Greenberger-Horne-Zeilinger paradoxes for continuous variables (2002)
Massar, Serge, Pironio, Stefano
We show how to construct Greenberger-Horn-Zeilinger type paradoxes for continuous variable systems. We give two examples corresponding to 3 party and 5 party paradoxes. The paradoxes are revealed by...
Greenberger-Horne-Zeilinger paradoxes for many qudits (2001)
Cerf, Nicolas J., Massar, Serge, Pironio, Stefano
We construct GHZ contradictions for three or more parties sharing an entangled state, the dimension d of each subsystem being an even integer greater than 2. The simplest example that goes beyond the...
How many photons are needed to distinguish two transparencies? (2001)
Mitchison, Graeme, Massar, Serge, Pironio, Stefano
We give a bound on the minimum number of photons that must be absorbed by any quantum protocol to distinguish between two transparencies. We show how a quantum Zeno method in which the angle of...
Greenberger-Horne-Zeilinger paradox for continuous variables (2001)
Massar, Serge, Pironio, Stefano
We show how to construct states for which a Greenberger-Horne-Zeilinger type paradox occurs if each party measures either the position or momentum of his particle. The paradox can be ascribed to the...
Minimal Absorption Measurements (2001)
Massar, Serge, Mitchison, Graeme, Pironio, Stefano
We show that it is not possible to discriminate two close transparencies without a certain number of photons being absorbed. We extend this to the discrimination of patterns of transparency (images).