Long-distance quantum communications with superactivated Gaussian optical quantum channels

2012 ◽  
Vol 51 (1) ◽  
pp. 015003 ◽  
Author(s):  
Laszlo Gyongyosi
Keyword(s):  
Quantum Channels ◽  
Quantum Communications ◽  
Long Distance

scholarly journals Twisted photon entanglement through turbulent air across Vienna

2015 ◽  
Vol 112 (46) ◽  
pp. 14197-14201 ◽  
Author(s):  
Mario Krenn ◽  
Johannes Handsteiner ◽  
Matthias Fink ◽  
Robert Fickler ◽  
Anton Zeilinger
Keyword(s):  
Angular Momentum ◽  
Quantum Entanglement ◽  
Quantum Communication ◽  
Entangled States ◽  
Phase Front ◽  
Quantum Channels ◽  
Long Distance ◽  
Large Alphabet ◽  
Large State Space ◽  
Promising Application

Photons with a twisted phase front can carry a discrete, in principle, unbounded amount of orbital angular momentum (OAM). The large state space allows for complex types of entanglement, interesting both for quantum communication and for fundamental tests of quantum theory. However, the distribution of such entangled states over large distances was thought to be infeasible due to influence of atmospheric turbulence, indicating a serious limitation on their usefulness. Here we show that it is possible to distribute quantum entanglement encoded in OAM over a turbulent intracity link of 3 km. We confirm quantum entanglement of the first two higher-order levels (with OAM=± 1ℏ and ± 2ℏ). They correspond to four additional quantum channels orthogonal to all that have been used in long-distance quantum experiments so far. Therefore, a promising application would be quantum communication with a large alphabet. We also demonstrate that our link allows access to up to 11 quantum channels of OAM. The restrictive factors toward higher numbers are technical limitations that can be circumvented with readily available technologies.

scholarly journals Polarization-Stable Long-Distance Interference of Independent Photons for Quantum Communications

2012 ◽  
Author(s):  
Thiago Ferreira da Silva ◽  
Douglas Vitoreti ◽  
Guilherme B. Xavier ◽  
Guilherme P. Temporão ◽  
Jean Pierre von der Weid
Keyword(s):  
Quantum Communications ◽  
Long Distance

Engineering of InAsP/InP quantum dot emission for long-distance quantum communications

2010 ◽  
Author(s):  
R. Hostein ◽  
M. Larqué ◽  
D. Elvira ◽  
B. Fain ◽  
A. Michon ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Quantum Communications ◽  
Long Distance

scholarly journals Spooky action at a global distance: analysis of space-based entanglement distribution for the quantum internet

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Sumeet Khatri ◽  
Anthony J. Brady ◽  
Renée A. Desporte ◽  
Manon P. Bart ◽  
Jonathan P. Dowling
Keyword(s):  
Global Scale ◽  
Quantum Communications ◽  
Quantum Repeater ◽  
Long Distance ◽  
Distance Analysis ◽  
Ground Station ◽  
Continuous Coverage ◽  
Entanglement Distribution ◽  
Near Term ◽  
Quantum Internet

AbstractRecent experimental breakthroughs in satellite quantum communications have opened up the possibility of creating a global quantum internet using satellite links. This approach appears to be particularly viable in the near term, due to the lower attenuation of optical signals from satellite to ground, and due to the currently short coherence times of quantum memories. The latter prevents ground-based entanglement distribution using atmospheric or optical-fiber links at high rates over long distances. In this work, we propose a global-scale quantum internet consisting of a constellation of orbiting satellites that provides a continuous, on-demand entanglement distribution service to ground stations. The satellites can also function as untrusted nodes for the purpose of long-distance quantum-key distribution. We develop a technique for determining optimal satellite configurations with continuous coverage that balances both the total number of satellites and entanglement-distribution rates. Using this technique, we determine various optimal satellite configurations for a polar-orbit constellation, and we analyze the resulting satellite-to-ground loss and achievable entanglement-distribution rates for multiple ground station configurations. We also provide a comparison between these entanglement-distribution rates and the rates of ground-based quantum repeater schemes. Overall, our work provides the theoretical tools and the experimental guidance needed to make a satellite-based global quantum internet a reality.

scholarly journals High-dimensional Private Quantum Channels and Regular Polytopes

2021 ◽  
Vol 31 (2) ◽  
pp. 189
Author(s):  
Junseo Lee ◽  
Kabgyun Jeong
Keyword(s):  
Quantum State ◽  
Quantum Channel ◽  
Three Dimensional ◽  
Quantum Channels ◽  
Regular Polytopes ◽  
Quantum Fourier Transform ◽  
Quantum Communications ◽  
Regular Polyhedra ◽  
Higher Dimensional ◽  
Quantum Analog

As the quantum analog of the classical one-time pad, the private quantum channel (PQC) plays a fundamental role in the construction of the maximally mixed state (from any input quantum state), which is very useful for studying secure quantum communications and quantum channel capacity problems. However, the undoubted existence of a relation between the geometric shape of regular polytopes and private quantum channels in the higher dimension has not yet been reported. Recently, it was shown that a one-to-one correspondence exists between single-qubit PQCs and three-dimensional regular polytopes (i.e., regular polyhedra). In this paper, we highlight these connections by exploiting two strategies known as a generalized Gell-Mann matrix and modified quantum Fourier transform. More precisely, we explore the explicit relationship between PQCs over a qutrit system (i.e., a three-level quantum state) and regular 4-polytopes. Finally, we attempt to devise a formula for such connections on higher dimensional cases.

scholarly journals Long-lived and multiplexed atom-photon entanglement interface with feed-forward-controlled readouts

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Sheng-zhi Wang ◽  
Min-jie Wang ◽  
Ya-fei Wen ◽  
Zhong-xiao Xu ◽  
Teng-fei Ma ◽  
...  
Keyword(s):  
Spin Wave ◽  
Single Mode ◽  
Fold Increase ◽  
Quantum Communications ◽  
Long Distance ◽  
Controlled System ◽  
Entanglement Generation ◽  
Feed Forward ◽  
Long Wavelength ◽  
Polarization Interferometer

AbstractQuantum interfaces (QIs) that generate entanglement between photonic and spin-wave (atomic memory) qubits are basic building block for quantum repeaters. Realizing ensemble-based repeaters in practice requires quantum memory providing long lifetimes and multimode capacity. Significant progress has been achieved on these separate goals. The remaining challenge is to combine the two attributes into a single QI. Here, by establishing spatial multimode, magnetic-field-insensitive and long-wavelength spin-wave storage in laser-cooled atoms inside a phase-passively-stabilized polarization interferometer, we constructed a multiplexed QI that stores up to three long-lived spin-wave qubits. Using a feed-forward-controlled system, we demonstrated that a multiplexed QI gives rise to a 3-fold increase in the atom–photon (photon–photon) entanglement-generation probability compared with single-mode QIs. For our multiplexed QI, the measured Bell parameter is 2.51±0.01 combined with a memory lifetime of up to 1 ms. This work represents a key step forward in realizing fiber-based long-distance quantum communications.

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