20. QUANTUM COMMUNICATION

Quantum Optics of Chiral Spin Networks

Date: 
2014-11-11
Author(s): 

Hannes Pichler, Tomás Ramos, Andrew J. Daley, Peter Zoller

Reference: 

Phys. Rev. A 91, 042116 (2015).

We study the driven-dissipative dynamics of a network of spin-1/2 systems coupled to one or more chiral 1D bosonic waveguides within the framework of a Markovian master equation. We determine how the interplay between a coherent drive and collective decay processes can lead to the formation of pure multipartite entangled steady states. The key ingredient for the emergence of these many-body dark states is an asymmetric coupling of the spins to left and right propagating guided modes.

Photonic quantum circuits with finite time delays

Date: 
2015-10-15 - 2016-06-07
Author(s): 

Hannes Pichler, Peter Zoller

Reference: 

Phys. Rev. Lett. 116, 093601 (2016).

We study the dynamics of photonic quantum circuits consisting of nodes coupled by quantum channels. We are interested in the regime where time delay in communication between the nodes is significant. This includes the problem of quantum feedback, where a quantum signal is fed back on a system with a time delay. We develop a matrix product state approach to solve the Quantum Stochastic Schrödinger Equation with time delays, which accounts in an efficient way for the entanglement of nodes with the stream of emitted photons in the waveguide, and thus the non-Markovian character of the dynamics.

Implementations for device-independent quantum key distribution

Date: 
2015-11-02 - 2016-03-07
Author(s): 

Alejandro Máttar, Antonio Acín

Reference: 

Physica Scripta, Volume 91, Number 4

Device-independent quantum key distribution (DIQKD) generates a secret key among two parties in a provably secure way without making assumptions about the internal working of the devices used in the protocol.

Cavity-based quantum networks with single atoms and optical photons

Date: 
2015-12-01
Author(s): 

Andreas Reiserer, Gerhard Rempe

Reference: 

Rev. Mod. Phys. 87, 1379 (2015)

Distributed quantum networks will allow users to perform tasks and to interact in ways which are not possible with present-day technology. Their implementation is a key challenge for quantum science and requires the development of stationary quantum nodes that can send and receive as well as store and process quantum information locally. The nodes are connected by quantum channels for flying information carriers, i.e., photons. These channels serve both to directly exchange quantum information between nodes and to distribute entanglement over the whole network.

Quantum communication complexity advantage implies violation of a Bell inequality

Date: 
2015-02-03
Author(s): 

Harry Buhrman, Lukasz Czekaj, Andrzej Grudka, Michal Horodecki, Pawel Horodecki, Marcin Markiewicz, Florian Speelman, Sergii Strelchuk

Reference: 

arXiv:1502.01058 [quant-ph]

We obtain a general connection between a quantum advantage in communication complexity and non-locality. We show that given any protocol offering a (sufficiently large) quantum advantage in communication complexity, there exists a way of obtaining measurement statistics which violate some Bell inequality. Our main tool is port-based teleportation.

On the Parallel Repetition of Multi-Player Games: The No-Signaling Case

Date: 
2014-05-21 - 2014-05-23
Author(s): 

Harry Buhrman, Serge Fehr, Christian Schaffner

Reference: 

Conference on the Theory of Quantum Computation, Communication & Cryptography (2014)

Quantum communication technology

Date: 
2010-07-08
Reference: 

N. Gisin and R.T. Thew, Electron. Lett. -- 8 July 2010 -- Volume 46, Issue 14, p.965–967

Quantum communication is built on a set of disruptive concepts and technologies. It is driven by fascinating physics and by promising applications. It requires a new mix of competencies, from telecom engineering to theoretical physics, from theoretical computer science to mechanical and electronic engineering. First applications have already found their way into niche markets, and university labs are working on futuristic quantum networks, but most of the surprises are still ahead of us.

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