Entangled state quantum key distribution and teleportation (Abstract only)

Author(s):  
A. Poppe
2010 ◽  
Vol 08 (07) ◽  
pp. 1141-1151 ◽  
Author(s):  
XI-HAN LI ◽  
XIAO-JIAO DUAN ◽  
FU-GUO DENG ◽  
HONG-YU ZHOU

Quantum entanglement is an important element of quantum information processing. Sharing entangled quantum states between two remote parties is a precondition of most quantum communication schemes. We will show that the protocol proposed by Yamamoto et al. (Phys. Rev. Lett.95 (2005) 040503) for transmitting single quantum qubit against collective noise with linear optics is also suitable for distributing the components of entanglements with some modifications. An additional qubit is introduced to reduce the effect of collective noise, and the receiver can take advantage of the time discrimination and the measurement results of the assistant qubit to reconstruct a pure entanglement with the sender. Although the scheme succeeds probabilistically, the fidelity of the entangled state is almost unity in principle. The resource used in our protocol to get a pure entangled state is finite, which establishes entanglement more easily in practice than quantum entanglement purification. Also, we discuss its application in quantum key distribution over a collective channel in detail.


Entropy ◽  
2020 ◽  
Vol 22 (4) ◽  
pp. 434
Author(s):  
F. Hadi Madjid ◽  
John M. Myers

Entangled states of light exhibit measurable correlations between light detections at separated locations. These correlations are exploited in entangled-state quantum key distribution. To do so involves setting up and maintaining a rhythm of communication among clocks at separated locations. Here, we try to disentangle our thinking about clocks as used in actual experiments from theories of time, such as special relativity or general relativity, which already differ between each other. Special relativity intertwines the concept of time with a particular definition of the synchronization of clocks, which precludes synchronizing every clock to every other clock. General relativity imposes additional barriers to synchronization, barriers that invite seeking an alternative depending on any global concept of time. To this end, we focus on how clocks are actually used in some experimental situations. We show how working with clocks without worrying about time makes it possible to generalize some designs for quantum key distribution and also clarifies the need for alternatives to the special-relativistic definition of synchronization.


2012 ◽  
Vol 26 (16) ◽  
pp. 1250109 ◽  
Author(s):  
A. BECIR ◽  
M. R. B. WAHIDDIN

In this paper, we derive tight bounds for the eavesdropping attacks on continuous variable quantum key distribution (CV-QKD) protocol that involves nonmaximally entangled states. We show that deriving bounds on the eavesdropper's accessible information based on the Heisenberg uncertainty yields upper bounds, but those bounds are not tight. For this reason, we follow different techniques to derive the desired tight bounds. The new bounds are tight for all CV-QKD protocols that involve two-mode entangled state. Our derivations are applied to direct and reverse reconciliation schemes of protocol implementation, respectively.


Author(s):  
H. Hubel ◽  
A. Fedrizzi ◽  
A. Poppe ◽  
T. Lorunser ◽  
A. Zeilinger

2020 ◽  
Vol 8 (6) ◽  
pp. 2911-2918

Cryptography is the specialty of encoding and decoding messages and exists as extended as the individuals have doubted from one another and need secure correspondence. The traditional techniques for encryption naturally depend on any among public key or secret key approaches. In general, the public key encryption depends on two keys, for example, public key and private key. Since encryption and decryption keys are different, it isn't important to safely distribute a key. In this approach, the difficult of the numerical issues is assumed, not demonstrated. All the security will be easily compromised if proficient factoring algorithms are found. In secret key encryption two clients at first create secret key, which is a long string of arbitrarily selected bits and safely shares between them. At that point the clients can utilize the secret key along with the algorithms to encryption and decryption information. The procedures are complicated and also planned such a way that every bit of output is based on every bit of input. There are two fundamental issues with secret key encryption; first one is that by breaking down the openly known encoding algorithms, it gets simpler to decrypt the message. The subsequent one is that it experiences key-conveyance issue. As a result of the ongoing improvements in quantum processing and quantum data hypothesis, the quantum computers presents genuine difficulties to generally utilized current cryptographic strategy. The improvement of quantum cryptography beat the deficiencies of old style cryptography and achieves these huge accomplishments by using the properties of infinitesimal articles, for example, photon with its polarization and entangled state. In this paper, Polarization by refraction based quantum key distribution (PR-QKD) is proposed for quantum key generation and distribution. The proposed work considers three basis of polarization such as rectilinear (horizontal and vertical), circular (left-circular and right-circular), ellipse (left-ellipse and rightellipse) and refraction factor. This quantum key can be used for secure communication between two users who are spatially separated and also offer intrusion detection ability to detect attackers. The theoretical approach and conceptual results are discussed in this paper.


2013 ◽  
Vol 275-277 ◽  
pp. 2511-2514
Author(s):  
Xiao Qiang Guo ◽  
Yan Yan ◽  
Li Chao Feng ◽  
Shi Qiu Zheng

Quantum cryptography is the use of quantum existence state as the key of information encrption and decryption, the principle is the Einstein called "mysterious long distance activities" quantum entangled state. It is a quantum mechanical phenomenon, regardless of the distance between the two particles far, a particle changes will affect another particle, compared with the traditional password technology has a higher level of security. Quantum cryptography is a research hotspot of international academia in recent years. We introduce quantum key distribution, quantum commitment, bounded quantum storage model, position based quantum cryptography and post-quantum cryptography.


2021 ◽  
Author(s):  
Ling-Jun Kong ◽  
Furong Zhang ◽  
Jingfeng Zhang ◽  
Yifan Sun ◽  
Xiangdong Zhang

Abstract Cryptography plays an important role in information security, which is widely applied in the various fields of society. Quantum cryptography has shown its great advantages in information security compared with the classical one. Two major directions of quantum cryptography are quantum key distribution (QKD) and quantum encryption, with the former focusing on secure key distribution and the latter focusing on encryption using quantum algorithms. In contrast to the well accepted success of the QKD, the development of quantum encryption is rather limited because of the difficulties of building up algorithms and the constructing the practical quantum computers. Here we propose a new scheme of quantum encryption based on high-dimensional entanglement holography. Firstly, we experimentally realize the quantum holography based on the high-dimensional orbital angular momentum (OAM) entanglement. Then, OAM-selective holographic scheme for quantum encryption is proposed and demonstrated. Our results show that introducing quantum entangled state into OAM holography makes the OAM holography possess infinite information channels and the transmission of information be absolute security in principle. Furthermore, decryption in the presence of strong noise is achieved. Our work opens up a new way to realize quantum information security.


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