scholarly journals Security bound of continuous-variable quantum key distribution with noisy coherent states and channel

2009 ◽  
Vol 42 (23) ◽  
pp. 235506 ◽  
Author(s):  
Yong Shen ◽  
Jian Yang ◽  
Hong Guo
Keyword(s):  
Quantum Key Distribution ◽  
Coherent States ◽  
Key Distribution ◽  
Continuous Variable ◽  
Security Bound

scholarly journals CONTINUOUS VARIABLE QUANTUM KEY DISTRIBUTION USING POLARIZED COHERENT STATES

2006 ◽  
Vol 20 (11n13) ◽  
pp. 1287-1296 ◽  
Author(s):  
A. VIDIELLA-BARRANCO ◽  
L. F. M. BORELLI
Keyword(s):  
Quantum Key Distribution ◽  
Coherent States ◽  
Key Distribution ◽  
Continuous Variable ◽  
Stokes Parameters ◽  
Continuous Variables ◽  
Commuting Operators ◽  
Incoming Beam ◽  
Ideal Situation ◽  
Quantum Counterpart

We discuss a continuous variables method of quantum key distribution employing strongly polarized coherent states of light. The key encoding is performed using the variables known as Stokes parameters, rather than the field quadratures. Their quantum counterpart, the Stokes operators Ŝi ( i =1,2,3), constitute a set of non-commuting operators, being the precision of simultaneous measurements of a pair of them limited by an uncertainty-like relation. Alice transmits a conveniently modulated two-mode coherent state, and Bob randomly measures one of the Stokes parameters of the incoming beam. After performing reconciliation and privacy amplification procedures, it is possible to distill a secret common key. We also consider a non-ideal situation, in which coherent states with thermal noise, instead of pure coherent states, are used for encoding.

scholarly journals Single-quadrature continuous-variable quantum key distribution

2016 ◽  
Vol 16 (13&14) ◽  
pp. 1081-1095
Author(s):  
Tobias Gehring ◽  
Christian S. Jacobsen ◽  
Ulrik L. Andersen
Keyword(s):  
Quantum Key Distribution ◽  
Coherent States ◽  
Key Distribution ◽  
Continuous Variable ◽  
Low Noise ◽  
Excess Noise ◽  
Quadrature Modulation ◽  
Amplitude Modulator

Most continuous-variable quantum key distribution schemes are based on the Gaussian modulation of coherent states followed by continuous quadrature detection using homodyne detectors. In all previous schemes, the Gaussian modulation has been carried out in conjugate quadratures thus requiring two independent modulators for their implementations. Here, we propose and experimentally test a largely simplified scheme in which the Gaussian modulation is performed in a single quadrature. The scheme is shown to be asymptotically secure against collective attacks, and considers a specific attack using asymmetric preparation and excess noise. We find that this protocol is considerably more sensitive to noise than other CVQKD schemes, as a consequence of the simplified implementation. A single-quadrature modulation approach renders the need for a costly amplitude modulator unnecessary, and thus facilitates commercialization of continuous-variable quantum key distribution, provided that the low noise requirement can be achieved.

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