scholarly journals Quantum key distribution using a two-way quantum channel

2014 ◽  
Vol 560 ◽  
pp. 46-61 ◽  
Author(s):  
Marco Lucamarini ◽  
Stefano Mancini
Keyword(s):  
Quantum Channel ◽  
Quantum Key Distribution ◽  
Key Distribution

scholarly journals Quantum key distribution with mismatched measurements over arbitrary channels

2017 ◽  
Vol 17 (3&4) ◽  
pp. 209-241
Author(s):  
Walter O. Krawec
Keyword(s):  
Quantum Channel ◽  
Quantum Key Distribution ◽  
Key Distribution ◽  
Rate Equations ◽  
Quantum Channels ◽  
Multiple Channel ◽  
Symmetric Quantum ◽  
Channel Statistics ◽  
Quantum Protocol ◽  
Measurement Bases

In this paper, we derive key-rate expressions for different quantum key distribution protocols. Our key-rate equations utilize multiple channel statistics, including those gathered from mismatched measurement bases - i.e., when Alice and Bob choose incompatible bases. In particular, we will consider an Extended B92 and a two-way semi-quantum protocol. For both these protocols, we demonstrate that their tolerance to noise is higher than previously thought - in fact, we will show the semi-quantum protocol can actually tolerate the same noise level as the fully quantum BB84 protocol. Along the way, we will also consider an optimal QKD protocol for various quantum channels. Finally, all the key-rate expressions which we derive in this paper are applicable to any arbitrary, not necessarily symmetric, quantum channel.

scholarly journals Security of quantum key distribution with state-dependent imperfections

2011 ◽  
Vol 11 (11&12) ◽  
pp. 937-947
Author(s):  
Hong-Wei Li ◽  
Zhen-Qiang Yin ◽  
Shuang Wang ◽  
Wan-Su Bao ◽  
Guang-Can Guo ◽  
...  
Keyword(s):  
Error Rate ◽  
Distribution System ◽  
Quantum Channel ◽  
Quantum Key Distribution ◽  
Phase Error ◽  
Key Distribution ◽  
The State ◽  
Secret Key ◽  
Quantum Bit ◽  
State Dependent

In practical quantum key distribution system, the state preparation and measurement have state-dependent imperfections comparing with the ideal BB84 protocol. If the state-dependent imperfection can not be regarded as an unitary transformation, it should not be considered as part of quantum channel noise introduced by the eavesdropper, the commonly used secret key rate formula GLLP can not be applied correspondingly. In this paper, the unconditional security of quantum key distribution with state-dependent imperfections will be analyzed by estimating upper bound of the phase error rate in the quantum channel and the imperfect measurement. Interestingly, since Eve can not control all phase error in the quantum key distribution system, the final secret key rate under constant quantum bit error rate can be improved comparing with the perfect quantum key distribution protocol.

scholarly journals Perfect Reconciliation in Quantum Key Distribution with Order-Two Frames

2021 ◽  
Author(s):  
Luis Adrián Lizama-Pérez ◽  
José Mauricio López-Romero
Keyword(s):  
Error Rate ◽  
Quantum Channel ◽  
Quantum Key Distribution ◽  
Key Distribution ◽  
Data Networks ◽  
Secret Key ◽  
Software Update ◽  
Channel Error ◽  
Almost All ◽  
Reconciliation Method

We present an error reconciliation method for Quantum Key Distribution (QKD) that corrects 100% of errors generated in regular binary frames transmitted over a noisy quantum channel regardless of the quantum channel error rate. In a previous investigation, we introduced a novel distillation QKD algorithm whose secret key rate descends linearly with respect to the channel error rate. Now, as the main achievement of this work, we demonstrate an improved algorithm capable of retaining almost all the secret information enclosed in the regular binary frames. Remarkably, this technique increases quadratically the secret key rate as a function of the double matching detection events and doubly quadratically in the number of the quantum pulses. Furthermore, this reconciliation method opens up the opportunity to use less attenuated quantum pulses, would allow greater QKD distances at drastically increased secret key rate. Since our method can be implemented as a software update, we hope that quantum key distribution technology would be fast deployed over global data networks in the quantum era.

scholarly journals SECURITY OF QUANTUM KEY DISTRIBUTION

2008 ◽  
Vol 06 (01) ◽  
pp. 1-127 ◽  
Author(s):  
RENATO RENNER
Keyword(s):  
Representation Theorem ◽  
Physical System ◽  
Quantum Channel ◽  
Quantum Key Distribution ◽  
Key Distribution ◽  
Symmetry Condition ◽  
Secret Key ◽  
Independence Condition ◽  
Security Proof ◽  
Joint State

Quantum Information Theory is an area of physics which studies both fundamental and applied issues in quantum mechanics from an information-theoretical viewpoint. The underlying techniques are, however, often restricted to the analysis of systems which satisfy a certain independence condition. For example, it is assumed that an experiment can be repeated independently many times or that a large physical system consists of many virtually independent parts. Unfortunately, such assumptions are not always justified. This is particularly the case for practical applications — e.g. in quantum cryptography — where parts of a system might have an arbitrary and unknown behavior. We propose an approach which allows us to study general physical systems for which the above mentioned independence condition does not necessarily hold. It is based on an extension of various information-theoretical notions. For example, we introduce new uncertainty measures, called smooth min- and max-entropy, which are generalizations of the von Neumann entropy. Furthermore, we develop a quantum version of de Finetti's representation theorem, as described below. Consider a physical system consisting of n parts. These might, for instance, be the outcomes of n runs of a physical experiment. Moreover, we assume that the joint state of this n-partite system can be extended to an (n + k)-partite state which is symmetric under permutations of its parts (for some k ≫ 1). The de Finetti representation theorem then says that the original n-partite state is, in a certain sense, close to a mixture of product states. Independence thus follows (approximatively) from a symmetry condition. This symmetry condition can easily be met in many natural situations. For example, it holds for the joint state of n parts, which are chosen at random from an arbitrary (n + k)-partite system. As an application of these techniques, we prove the security of quantum key distribution (QKD), i.e. secret key agreement by communication over a quantum channel. In particular, we show that, in order to analyze QKD protocols, it is generally sufficient to consider so-called collective attacks, where the adversary is restricted to applying the same operation to each particle sent over the quantum channel separately. The proof is generic and thus applies to known protocols such as BB84 and B92 (where better bounds on the secret-key rate and on the the maximum tolerated noise level of the quantum channel are obtained) as well as to continuous variable schemes (where no full security proof has been known). Furthermore, the security holds with respect to a strong so-called universally composable definition. This implies that the keys generated by a QKD protocol can safely be used in any application, e.g. for one-time pad encryption — which, remarkably, is not the case for most standard definitions.

AUTHENTICATED QUANTUM KEY DISTRIBUTION WITHOUT CLASSICAL COMMUNICATION

2007 ◽  
Vol 17 (03) ◽  
pp. 323-335 ◽  
Author(s):  
NAYA NAGY ◽  
SELIM G. AKL
Keyword(s):  
Quantum Channel ◽  
Quantum Key Distribution ◽  
Communication Channel ◽  
Quantum Communication ◽  
Key Distribution ◽  
Secret Key ◽  
Classical Communication ◽  
Quantum Communication Channel ◽  
High Security ◽  
Public Keys

The aim of quantum key distribution protocols is to establish a secret key among two parties with high security confidence. Such algorithms generally require a quantum channel and an authenticated classical channel. This paper presents a totally new perception of communication in such protocols. The quantum communication alone satisfies all needs of array communication between the two parties. Even so, the quantum communication channel does not need to be protected or authenticated whatsoever. As such, our algorithm is a purely quantum key distribution algorithm. The only certain identification of the two parties is through public keys.

scholarly journals A Quantum Cipher with Near Optimal Key-Recycling

2005 ◽  
Vol 12 (17) ◽  
Author(s):  
Ivan B. Damgård ◽  
Thomas B. Pedersen ◽  
Louis Salvail
Keyword(s):  
Quantum Channel ◽  
Arbitrary Number ◽  
Quantum Key Distribution ◽  
Key Distribution ◽  
Shared Key ◽  
Almost All ◽  
Ordinary Quantum

Assuming an insecure quantum channel and an authenticated classical channel, we propose an unconditionally secure scheme for encrypting classical messages under a shared key, where attempts to eavesdrop the ciphertext can be detected. If no eavesdropping is detected, we can securely re-use the entire key for encrypting new messages. If eavesdropping is detected, we must discard a number of key bits corresponding to the length of the message, but can re-use almost all of the rest. We show this is essentially optimal. Thus, provided the adversary does not interfere (too much) with the quantum channel, we can securely send an arbitrary number of message bits, independently of the length of the initial key. Moreover, the key-recycling mechanism only requires one-bit feedback. While ordinary quantum key distribution with a classical one time pad could be used instead to obtain a similar functionality, this would need more rounds of interaction and more communication.

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