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1.
We present a new protocol for continuous variable quantum key distribution (CV QKD). The novelty of the protocol is a multi
letter alphabet represented by coherent states of light with a fixed amplitude and variable phase. Information is encoded
in the phase of a coherent state which can be chosen from a regular discrete set consisting, however, of an arbitrary number
of letters. We evaluate the security of the protocol against the beam splitting attack. As a result we show the proposed protocol
has advantages over the standard two letter coherent state QKD protocol, especially in the case when losses in the communication
channel are low. 相似文献
2.
Quantum key distribution using different-frequency photons 总被引:1,自引:0,他引:1
In this paper, we present a scheme for quantum key distribution, in which different-frequency photons are used to encode the key. These different-frequency photons are produced by an acoustic-optical modulator and two kinds of narrow filters. This scheme may be implementable in practice. 相似文献
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P.J. Edwards G.H. Pollard W.N. Cheung 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(2):147-153
Quantum key exchanges using weak coherent (Poissonian) single-photon sources are open to attack by a variety of eavesdropping
techniques. Quantum-correlated photon sources provide a means of flagging potentially insecure multiple-photon emissions and
thus extending the secure quantum key channel capacity and the secure key distribution range. We present indicative photon-counting
statistics for a fully correlated Poissonian multibeam photon source in which the transmitted beam is conditioned by photon
number measurements on the remaining beams with non-ideal multiphoton counters. We show that significant rejection of insecure
photon pulses from a twin-beam source cannot be obtained with a detector having a realistic quantum efficiency. However quantum-correlated
(quadruplet or octuplet) multiplet photon sources conditioned by high efficiency multiphoton counters could provide large
improvements in the secure channel capacity and the secure distribution range of high loss systems such as those using the
low earth orbit satellite links proposed for global quantum key distribution.
Received 14 July and Received in final form 20 November 2001 相似文献
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Subhash Kak 《Pramana》2000,54(5):709-713
This note presents a method of public key distribution using quantum communication of n photons that simultaneously provides a high probability that the bits have not been tampered. It is a variant of the quantum
method of Bennett and Brassard (BB84) where the transmission states have been decreased from 4 to 3 and the detector states
have been increased from 2 to 3. Under certain assumptions regarding method of attack, it provides superior performance (in
terms of the number of usable key bits) for n<18m, where m is the number of key bits used to verify the integrity of the process in the BB84-protocol. 相似文献
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Secure key distribution among two remote parties is impossible when both are classical, unless some unproven computation-complexity assumptions are made, such as the difficulty of factorizing large numbers. On the other hand, a secure key distribution is possible when both parties are quantum. What is possible when only one party (Alice) is quantum, yet the other (Bob) has only classical capabilities? We present a protocol with this constraint and prove its robustness against attacks: we prove that any attempt of an adversary to obtain information necessarily induces some errors that the legitimate users could notice. 相似文献
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A modified attack scheme base on GHZ state is proposed. The relationships among QBER, ratio of qubits which eavesdropped by Eve(eavesdropper) and average photon number in signal state were analysed. The simulation shows that when Eve attacks all of the multi-photons state pulses and the 43% of single-photon state pulses he can get about 46% original qubits which shared between Alice (sender) and Bob (receiver). And the average photon number of the signal state affect the QBER and the leaked information non-linearly. 相似文献
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We propose a new quantum key distribution scheme that uses the blind polarization basis. In our scheme the sender and the receiver share key information by exchanging qubits with arbitrary polarization angles without basis reconciliation. As only random polarizations are transmitted, our protocol is secure even when a key is embedded in a not-so-weak coherent-state pulse. We show its security against the photon-number splitting attack and the impersonation attack. 相似文献
10.
Quantum key distribution with bright entangled beams 总被引:1,自引:0,他引:1
We suggest a quantum cryptographic scheme using continuous EPR-like correlations of bright optical beams. For binary key encoding, the continuous information is discretized in a novel way by associating a respective measurement, amplitude, or phase, with a bit value "1" or "0." The secure key distribution is guaranteed by the quantum correlations. No predetermined information is sent through the quantum channel contributing to the security of the system. 相似文献
11.
Wang XB 《Physical review letters》2004,92(7):077902
We propose a prepare-and-measure scheme for quantum key distribution with two-qubit quantum codes. The protocol is unconditionally secure under all types of intercept-and-resend attack. Given the symmetric and independent errors to the transmitted qubits, our scheme can tolerate a bit of an error rate up to 26% in four-state protocol and 30% in six-state protocol, respectively. These values are higher than all currently known threshold values for the prepare-and-measure protocols. Moreover, we give a practically implementable linear optics realization for our scheme. 相似文献
12.
The operational inclusion of the subclass of entangled states in a quantum key distribution protocol based on biphoton-ququarts is analyzed. Four Bell states are proposed to be used as test states to estimate the error level, leaving the subclass of 12 factorized polarization states of biphotons as information states. The elementary analysis of two strategies for an attack on a quantum communication channel, as well as of the key generation rate, has been performed. 相似文献
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S. N. Molotkov 《Journal of Experimental and Theoretical Physics》2011,113(5):743-754
A new quantum key distribution protocol stable at arbitrary losses in a quantum communication channel has been proposed. For
the stability of the protocol, it is of fundamental importance that changes in states associated with losses in the communication
channel (in the absence of the eavesdropper) are included in measurements. 相似文献
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The operational inclusion of the subclass of entangled states in a quantum key distribution protocol based on biphoton-ququarts is analyzed. Four Bell states are proposed to be used as test states to estimate the error level, leaving the subclass of 12 factorized polarization states of biphotons as information states. The elementary analysis of two strategies for an attack on a quantum communication channel, as well as of the key generation rate, has been performed.
相似文献15.
Quantum hacking of two-way continuous-variable quantum key distribution using Trojan-horse attack 下载免费PDF全文
We present a Trojan-horse attack on the practical two-way continuous-variable quantum key distribution system. Our attack mainly focuses on the imperfection of the practical system that the modulator has a redundancy of modulation pulsewidth, which leaves a loophole for the eavesdropper inserting a Trojan-horse pulse. Utilizing the unique characteristics of two-way continuous-variable quantum key distribution that Alice only takes modulation operation on the received mode without any measurement, this attack allows the eavesdropper to render all of the final keys shared between the legitimate parties insecure without being detected. After analyzing the feasibility of the attack, the corresponding countermeasures are put forward. 相似文献
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T. Hwang C. C. Hwang C. W. Tsai 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,61(3):785-790
The three-qubit W state, with an important feature that each pair
of it’s qubits has the same and maximum amount of bipartite entanglement,
can be reduced to an entangled 2-qubit system if one of its qubits
is lost. Recently, Xue et al. proposed a three-party quantum secret
sharing (QSS) protocol based on the three-qubit W state [Chinese Phys. 15, 7 (2006)]. Also, Joo
et al. proposed a pair-wise quantum key distribution protocol among
three users based on a special measurement on the three-qubit W state [eprint arXiv:quant-ph/0204003v2 (2002)].
This study aims to propose a novel quantum key distribution protocol
(QKDP) for arbitrary two communications based on the dense coding
and the special measurement of three-qubit W state with the X basis
and the Z basis. 相似文献
17.
A quantum circuit is constructed for optimal eavesdropping on quantum key distribution proto- cols using phase-time coding,
and its physical implementation based on linear and nonlinear fiber-optic components is proposed. 相似文献
18.
N. Lütkenhaus 《Applied physics. B, Lasers and optics》1999,69(5-6):395-400
Quantum key distribution bears the promise to set new standards in secure communication. However, on the way from the theoretical
principles to the practical implementation we find many obstacles that need to be taken care of. In this article I show how
to obtain a key with a realistic setup such that the security of this key can be proven for an important restricted class
of eavesdropping attacks, namely the individual attacks.
Received: 15 June 1999 / Published online: 3 November 1999 相似文献
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Either collective-dephasing noise or collective-rotation noise is considered, two efficient quantum key distribution protocols are presented. With eight product states of three EPR pairs, two bits of secret key can be distributed successfully in each six-photon state. Comparing with the four-photon secret key distribution protocols, the security is also enhanced by using three sets (or more) of measurement bases. 相似文献