Home › IPs

Q-ESSENCE

Tensor Rank and Stochastic Entanglement Catalysis for Multipartite Pure States

Mon, 2011-02-14 17:29 - Q-Essence Coordinator
Date: 
2010-11-08
Author(s): 

Lin Chen, Eric Chitambar, Runyao Duan, Zhengfeng Ji, and Andreas Winter

Reference: 

Phys. Rev. Lett. 105, 200501 (2010)

URL: 

http://link.aps.org/doi/10.1103/PhysRevLett.105.200501

Quantum networks reveal quantum nonlocality

Mon, 2011-02-14 17:21 - Q-Essence Coordinator
Date: 
2011-02-08
Author(s): 

Daniel Cavalcanti, Mafalda L. Almeida, Valerio Scarani and Antonio Acín

Reference: 

Nat. Commun. 2 , 184 (2011)
doi:10.1038/ncomms1193 (2011)

The results of local measurements on some composite quantum systems cannot be reproduced classically. This impossibility, known as quantum nonlocality, represents a milestone in the foundations of quantum theory. Quantum nonlocality is also a valuable resource for information-processing tasks, for example, quantum communication, quantum key distribution, quantum state estimation or randomness extraction. Still, deciding whether a quantum state is nonlocal remains a challenging problem.

Hybrid Long-Distance Entanglement Distribution Protocol

Mon, 2011-02-14 16:55 - Q-Essence Coordinator
Date: 
2010-10-11
Author(s): 

J. B. Brask, I. Rigas, E. S. Polzik, U. L. Andersen, and A. S. Sørensen

Reference: 

Phys. Rev. Lett. 105, 160501 (2010)

URL: 

http://link.aps.org/doi/10.1103/PhysRevLett.105.160501

We propose a hybrid (continuous-discrete variable) quantum repeater protocol for long-distance entanglement distribution. Starting from states created by single-photon detection, we show how entangled coherent state superpositions can be generated by means of homodyne detection. We show that near-deterministic entanglement swapping with such states is possible using only linear optics and homodyne detectors, and we evaluate the performance of our protocol combining these elements.

 

Giant Stark effect in the emission of single semiconductor quantum dots

Mon, 2011-02-14 16:49 - Q-Essence Coordinator
Date: 
2010-07-19
Author(s): 

Anthony J. Bennett, Raj B. Patel, Joanna Skiba-Szymanska, Christine A. Nicoll, Ian Farrer, David A. Ritchie, and Andrew J. Shields

Reference: 

Appl. Phys. Lett. 97, 031104 (2010)

URL: 

http://link.aip.org/link/doi/10.1063/1.3460912

We study the quantum-confined Stark effect in single InAs/GaAs quantum dots embedded within a AlGaAs/GaAs/AlGaAs quantum well. By significantly increasing the barrier height we can observe emission from a dot at electric fields of 500 kV cm−1, leading to Stark shifts of up to 25 meV. Our results suggest this technique may enable future applications that require self-assembled dots with transitions at the same energy.

 

Bound Nonlocality and Activation

Mon, 2011-02-14 16:09 - Q-Essence Coordinator
Date: 
2011-01-10
Author(s): 

Nicolas Brunner, Daniel Cavalcanti, Alejo Salles, and Paul Skrzypczyk

Reference: 

Phys. Rev. Lett. 106, 020402 (2011)

URL: 

http://link.aps.org/doi/10.1103/PhysRevLett.106.020402

We investigate nonlocality distillation using measures of nonlocality based on the Elitzur-Popescu-Rohrlich decomposition. For a certain number of copies of a given nonlocal box, we define two quantities of interest: (i) the nonlocal cost and (ii) the distillable nonlocality. We find that there exist boxes whose distillable nonlocality is strictly smaller than their nonlocal cost. Thus nonlocality displays a form of irreversibility which we term “bound nonlocality.” Finally, we show that nonlocal distillability can be activated.

Noisy evolution of graph-state entanglement

Sat, 2011-02-12 14:03 - Q-Essence Coordinator
Date: 
2010-09-21
Author(s): 

L. Aolita, D. Cavalcanti, R. Chaves, C. Dhara, L. Davidovich, and A. Acín

Reference: 

Phys. Rev. A 82, 032317 (2010)

URL: 

http://link.aps.org/doi/10.1103/PhysRevA.82.032317

Syndicate content