Hierarchical simultaneous entanglement swapping for multi-hop quantum communication based on multi-particle entangled states

2020 ◽  
Author(s):  
Guang Yang ◽  
Lei Xing ◽  
Min Nie ◽  
Yuan-Hua Liu ◽  
Mei-Ling Zhang
Keyword(s):  
Quantum Communication ◽  
Entanglement Swapping ◽  
Entangled States

A quantum repeater based on decoherence free subspaces

2008 ◽  
Vol 8 (5) ◽  
pp. 468-488
Author(s):  
U. Dorner ◽  
A. Klein ◽  
D. Jaksch
Keyword(s):  
Quantum Communication ◽  
Waiting Times ◽  
Entanglement Swapping ◽  
Quantum Gates ◽  
Quantum Repeater ◽  
Decoherence Free Subspace ◽  
Decoherence Free Subspaces

We study a quantum repeater which is based on decoherence free quantum gates recently proposed by Klein {\it et al.} [Phys. Rev. A, {\bf 73}, 012332 (2006)]. A number of operations on the decoherence free subspace in this scheme makes use of an ancilla qubit, which undergoes dephasing and thus introduces decoherence to the system. We examine how this decoherence affects entanglement swapping and purification as well as the performance of a quantum repeater. We compare the decoherence free quantum repeater with a quantum repeater based on qubits that are subject to decoherence and show that it outperforms the latter when decoherence due to long waiting times of conventional qubits becomes significant. Thus, a quantum repeater based on decoherence free subspaces is a possibility to greatly improve quantum communication over long or even intercontinental distances.

Long distance two-party quantum crypto made simple

2012 ◽  
Vol 12 (5&6) ◽  
pp. 448-460
Author(s):  
Iordanis Kerenidis ◽  
Stephanie Wehner
Keyword(s):  
Quantum Communication ◽  
Oblivious Transfer ◽  
Difficult Problem ◽  
Entanglement Swapping ◽  
Quantum States ◽  
Large Network ◽  
Long Distance ◽  
Computational Problem ◽  
Cryptographic Primitive

Any two-party cryptographic primitive can be implemented using quantum communication under the assumption that it is difficult to store a large number of quantum states perfectly. However, achieving reliable quantum communication over long distances remains a difficult problem. Here, we consider a large network of nodes with only neighboring quantum links. We exploit properties of this cloud of nodes to enable any two nodes to achieve security even if they are not directly connected. Our results are based on techniques from classical cryptography and do not resort to technologically difficult procedures like entanglement swapping. More precisely, we show that oblivious transfer can be achieved in such a network if and only if there exists a path in the network between the sender and the receiver along which all nodes are honest. Finally, we show that useful notions of security can still be achieved when we relax the assumption of an honest path. For example, we show that we can combine our protocol for oblivious transfer with computational assumptions such that we obtain security if either there exists an honest path, or, as a backup, at least the adversary cannot solve a computational problem.

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 Device-independent randomness generation with sublinear shared quantum resources

Quantum ◽  
2018 ◽  
Vol 2 ◽  
pp. 86 ◽  
Author(s):  
Cédric Bamps ◽  
Serge Massar ◽  
Stefano Pironio
Keyword(s):  
Quantum Cryptography ◽  
Quantum Communication ◽  
Random Number ◽  
Essential Feature ◽  
Random Number Generation ◽  
Fundamental Question ◽  
Entangled States ◽  
Number Generation ◽  
Singlet States ◽  
Partially Entangled States

In quantum cryptography, device-independent (DI) protocols can be certified secure without requiring assumptions about the inner workings of the devices used to perform the protocol. In order to display nonlocality, which is an essential feature in DI protocols, the device must consist of at least two separate components sharing entanglement. This raises a fundamental question: how much entanglement is needed to run such DI protocols? We present a two-device protocol for DI random number generation (DIRNG) which produces approximatelynbits of randomness starting fromnpairs of arbitrarily weakly entangled qubits. We also consider a variant of the protocol wheremsinglet states are diluted intonpartially entangled states before performing the first protocol, and show that the numbermof singlet states need only scale sublinearly with the numbernof random bits produced. Operationally, this leads to a DIRNG protocol between distant laboratories that requires only a sublinear amount of quantum communication to prepare the devices.

scholarly journals Entanglement swapping of two arbitrarily degraded entangled states

2016 ◽  
Vol 94 (1) ◽  
Author(s):  
Brian T. Kirby ◽  
Siddhartha Santra ◽  
Vladimir S. Malinovsky ◽  
Michael Brodsky
Keyword(s):  
Entanglement Swapping ◽  
Entangled States

ENTANGLEMENT SWAPPING AND QUANTUM COMMUNICATION IN CAVITY QED

2008 ◽  
Vol 06 (06) ◽  
pp. 1255-1262 ◽  
Author(s):  
CHUAN-JIA SHAN ◽  
JI-BING LIU ◽  
WEI-WEN CHENG ◽  
TANG-KUN LIU ◽  
YAN-XIA HUANG ◽  
...  
Keyword(s):  
Cavity Qed ◽  
Quantum Communication ◽  
Communication Protocol ◽  
Success Probability ◽  
Entanglement Swapping ◽  
Direct Communication

We study entanglement swapping and quantum communication in the context of cavity QED. We first present an entanglement swapping scheme in cavities where two atoms without interacting previously can be entangled with the success probability unity. Then, conditioned on a novel property of entanglement swapping, we propose a secure direct communication protocol, in which two legitimate users can communicate deterministically.

Dynamics of multi-qubit states in non-inertial frames for quantum communication applications

2014 ◽  
Vol 14 (3&4) ◽  
pp. 255-264
Author(s):  
Alaa Sagheer ◽  
Hala Hamdoun
Keyword(s):  
Degradation Rate ◽  
Quantum Communication ◽  
Ghz State ◽  
The Other ◽  
W State ◽  
Entangled States ◽  
Inertial Frames ◽  
Qubit States ◽  
Degree Of Entanglement ◽  
Accelerated Frames

In this paper, some properties of multi-qubit states traveling in non-inertial frames are investigated, where we assume that all particles are accelerated. These properties are including fidelities, capacities and entanglement of the accelerated channels for three different states, namely, Greeberger-Horne-Zeilinger (GHZ) state, GHZ-like state and W-state. It is shown here that all these properties are decreased as the accelerations of the moving particles are increased. The obtained results show that the GHZ-state is the most robust state comparing to the others, where the degradation rate is less than that for the other states particularly in the second Rindler region. Also, it is shown here that the entangled property doesn't change in the accelerated frames. Additionally, the paper shows that the degree of entanglement decreases as the accelerations of the particles increase in the first Rindler region. However in the second region, where all subsystems are disconnected at zero acceleration, entangled states are generated as the acceleration increases.

Generation of Gaussian-modulated entangled states for continuous variable quantum communication

2019 ◽  
Vol 44 (15) ◽  
pp. 3613
Author(s):  
Ning Wang ◽  
Shanna Du ◽  
Wenyuan Liu ◽  
Xuyang Wang ◽  
Yongmin Li
Keyword(s):  
Quantum Communication ◽  
Continuous Variable ◽  
Entangled States
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