ENTANGLEMENT VERIFICATION WITH AN APPLICATION TO QUANTUM KEY DISTRIBUTION PROTOCOLS

2010 ◽  
Vol 20 (03) ◽  
pp. 227-237 ◽  
Author(s):  
MARIUS NAGY ◽  
SELIM G. AKL

We develop an entanglement verification method not based on Bell inequalities, that achieves a higher reliability per number of qubits tested than existing procedures of this kind. Used in a quantum cryptographic context, the method gives rise to a new protocol for distributing classical keys through insecure quantum channels. The cost of quantum and classical communication is significantly reduced in the new protocol, while its security is increased with respect to other entanglement-based protocols exchanging the same number of qubits. To achieve this performance, our scheme relies on a simple quantum circuit and the ability to store qubits.

2015 ◽  
Vol 15 (15&16) ◽  
pp. 1295-1306
Author(s):  
Zoe Amblard ◽  
Francois Arnault

The Ekert quantum key distribution protocol [1] uses pairs of entangled qubits and performs checks based on a Bell inequality to detect eavesdropping. The 3DEB protocol [2] uses instead pairs of entangled qutrits to achieve better noise resistance than the Ekert protocol. It performs checks based on a Bell inequality for qutrits named CHSH-3 and found in [3, 4]. In this paper, we present a new protocol, which also uses pairs of entangled qutrits, but gaining advantage of a Bell inequality which achieves better noise resistance than the one used in 3DEB. The latter inequality is called here hCHSH-3 and was discovered in [5]. For each party, the hCHSH-3 inequality involves four observables already used in CHSH-3 but also two products of observables which do not commute. We explain how the parties can measure the observables corresponding to these products and thus are able to check the violation of hCHSH-3. In the presence of noise, this violation guarantees the security against a local Trojan horse attack. We also designed a version of our protocol which is secure against individual attacks.


2012 ◽  
Vol 10 (05) ◽  
pp. 1250059 ◽  
Author(s):  
MAOZHU SUN ◽  
XIANG PENG ◽  
YUJIE SHEN ◽  
HONG GUO

The original two-way continuous-variable quantum-key-distribution (CV-QKD) protocols [S. Pirandola, S. Mancini, S. Lloyd and S. L. Braunstein, Nat. Phys. 4 (2008) 726] give the security against the collective attack on the condition of the tomography of the quantum channels. We propose a family of new two-way CV-QKD protocols and prove their security against collective entangling cloner attacks without the tomography of the quantum channels. The simulation result indicates that the new protocols maintain the same advantage as the original two-way protocols whose tolerable excess noise surpasses that of the one-way CV-QKD protocol. We also show that all sub-protocols within the family have higher secret key rate and much longer transmission distance than the one-way CV-QKD protocol for the noisy channel.


2010 ◽  
Vol 283 (12) ◽  
pp. 2644-2646 ◽  
Author(s):  
Chang Ho Hong ◽  
Jin O Heo ◽  
Gyong Luck Khym ◽  
Jongin Lim ◽  
Suc-Kyung Hong ◽  
...  

2007 ◽  
Vol 76 (3) ◽  
Author(s):  
Shun Watanabe ◽  
Ryutaroh Matsumoto ◽  
Tomohiko Uyematsu ◽  
Yasuhito Kawano

2017 ◽  
Vol 17 (3&4) ◽  
pp. 209-241
Author(s):  
Walter O. Krawec

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.


Quantum ◽  
2022 ◽  
Vol 6 ◽  
pp. 613
Author(s):  
Ignatius William Primaatmaja ◽  
Cassey Crystania Liang ◽  
Gong Zhang ◽  
Jing Yan Haw ◽  
Chao Wang ◽  
...  

Most quantum key distribution (QKD) protocols can be classified as either a discrete-variable (DV) protocol or continuous-variable (CV) protocol, based on how classical information is being encoded. We propose a protocol that combines the best of both worlds – the simplicity of quantum state preparation in DV-QKD together with the cost-effective and high-bandwidth of homodyne detectors used in CV-QKD. Our proposed protocol has two highly practical features: (1) it does not require the honest parties to share the same reference phase (as required in CV-QKD) and (2) the selection of decoding basis can be performed after measurement. We also prove the security of the proposed protocol in the asymptotic limit under the assumption of collective attacks. Our simulation suggests that the protocol is suitable for secure and high-speed practical key distribution over metropolitan distances.


Entropy ◽  
2019 ◽  
Vol 21 (4) ◽  
pp. 333 ◽  
Author(s):  
Xiaodong Wu ◽  
Yijun Wang ◽  
Qin Liao ◽  
Hai Zhong ◽  
Ying Guo

We propose a simultaneous classical communication and quantum key distribution (SCCQ) protocol based on plug-and-play configuration with an optical amplifier. Such a protocol could be attractive in practice since the single plug-and-play system is taken advantage of for multiple purposes. The plug-and-play scheme waives the necessity of using two independent frequency-locked laser sources to perform coherent detection, thus the phase noise existing in our protocol is small which can be tolerated by the SCCQ protocol. To further improve its capabilities, we place an optical amplifier inside Alice’s apparatus. Simulation results show that the modified protocol can well improve the secret key rate compared with the original protocol whether in asymptotic limit or finite-size regime.


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