skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Controlling excess noise in fiber-optics continuous-variable quantum key distribution

Abstract

We describe a continuous-variable coherent-states quantum-key distribution system working at 1550 nm, and entirely made of standard fiber optics and telecommunications components, such as integrated-optics modulators, couplers and fast InGaAs photodiodes. The setup is composed of an emitter randomly modulating a coherent state in the complex plane with a doubly Gaussian distribution, and a receiver based on a shot-noise limited time-resolved homodyne detector. By using a reverse reconciliation protocol, the device can transfer a raw key rate up to 1 Mbit/s, with a proven security against Gaussian or non-Gaussian attacks. The dependence of the secret information rate of the present fiber setup is studied as a function of the line transmission and excess noise.

Authors:
 [1];  [2];  [1]; ;  [3]
  1. Thales Research and Technologies, RD 128 91767 Palaiseau CEDEX (France)
  2. (France)
  3. Laboratoire Charles Fabry de l'Institut d'Optique, Campus Universitaire, Batiment 503 91403 Orsay CEDEX (France)
Publication Date:
OSTI Identifier:
20786417
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 72; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevA.72.050303; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; ANNIHILATION OPERATORS; DATA TRANSMISSION; DISTRIBUTION; EIGENSTATES; FIBER OPTICS; GAUSS FUNCTION; INFORMATION THEORY; NOISE; OPTICAL FIBERS; PHOTODIODES; QUANTUM CRYPTOGRAPHY; SECRECY PROTECTION; TIME RESOLUTION

Citation Formats

Lodewyck, Jerome, Laboratoire Charles Fabry de l'Institut d'Optique, Campus Universitaire, Batiment 503 91403 Orsay CEDEX, Debuisschert, Thierry, Tualle-Brouri, Rosa, and Grangier, Philippe. Controlling excess noise in fiber-optics continuous-variable quantum key distribution. United States: N. p., 2005. Web. doi:10.1103/PHYSREVA.72.0.
Lodewyck, Jerome, Laboratoire Charles Fabry de l'Institut d'Optique, Campus Universitaire, Batiment 503 91403 Orsay CEDEX, Debuisschert, Thierry, Tualle-Brouri, Rosa, & Grangier, Philippe. Controlling excess noise in fiber-optics continuous-variable quantum key distribution. United States. doi:10.1103/PHYSREVA.72.0.
Lodewyck, Jerome, Laboratoire Charles Fabry de l'Institut d'Optique, Campus Universitaire, Batiment 503 91403 Orsay CEDEX, Debuisschert, Thierry, Tualle-Brouri, Rosa, and Grangier, Philippe. Tue . "Controlling excess noise in fiber-optics continuous-variable quantum key distribution". United States. doi:10.1103/PHYSREVA.72.0.
@article{osti_20786417,
title = {Controlling excess noise in fiber-optics continuous-variable quantum key distribution},
author = {Lodewyck, Jerome and Laboratoire Charles Fabry de l'Institut d'Optique, Campus Universitaire, Batiment 503 91403 Orsay CEDEX and Debuisschert, Thierry and Tualle-Brouri, Rosa and Grangier, Philippe},
abstractNote = {We describe a continuous-variable coherent-states quantum-key distribution system working at 1550 nm, and entirely made of standard fiber optics and telecommunications components, such as integrated-optics modulators, couplers and fast InGaAs photodiodes. The setup is composed of an emitter randomly modulating a coherent state in the complex plane with a doubly Gaussian distribution, and a receiver based on a shot-noise limited time-resolved homodyne detector. By using a reverse reconciliation protocol, the device can transfer a raw key rate up to 1 Mbit/s, with a proven security against Gaussian or non-Gaussian attacks. The dependence of the secret information rate of the present fiber setup is studied as a function of the line transmission and excess noise.},
doi = {10.1103/PHYSREVA.72.0},
journal = {Physical Review. A},
number = 5,
volume = 72,
place = {United States},
year = {Tue Nov 15 00:00:00 EST 2005},
month = {Tue Nov 15 00:00:00 EST 2005}
}
  • In realistic continuous-variable quantum key distribution protocols, an eavesdropper may exploit the additional Gaussian noise generated during transmission to mask her presence. We present a theoretical framework for a post-selection-based protocol which explicitly takes into account excess Gaussian noise. We derive a quantitative expression of the secret key rates based on the Levitin and Holevo bounds. We experimentally demonstrate that the post-selection-based scheme is still secure against both individual and collective Gaussian attacks in the presence of this excess noise.
  • Source noise affects the security of continuous-variable quantum key distribution (CV QKD) and is difficult to analyze. We propose a model to characterize Gaussian source noise through introducing a neutral party (Fred) who induces the noise with a general unitary transformation. Without knowing Fred's exact state, we derive the security bounds for both reverse and direct reconciliations and show that the bound for reverse reconciliation is tight.
  • We report on the implementation of a reverse-reconciliated coherent-state continuous-variable quantum key distribution system, with which we generated secret keys at a rate of more than 2 kb/s over 25 km of optical fiber. Time multiplexing is used to transmit both the signal and phase reference in the same optical fiber. Our system includes all experimental aspects required for a field implementation of a quantum key distribution setup. Real-time reverse reconciliation is achieved by using fast and efficient low-density parity check error correcting codes.
  • We investigate the security of continuous-variable quantum key distribution using coherent states and reverse reconciliation against Gaussian individual attacks based on an optimal Gaussian 1{yields}2 cloning machine. We provide an implementation of the optimal Gaussian individual attack. We also find a Bell-measurement attack which works without delayed choice of measurements and has better performance than the cloning attack.
  • We propose efficient-phase-encoding protocols for continuous-variable quantum key distribution using coherent states and postselection. By these phase encodings, the probability of basis mismatch is reduced and total efficiency is increased. We also propose mixed-state protocols by omitting a part of classical communication steps in the efficient-phase-encoding protocols. The omission implies a reduction of information to an eavesdropper and possibly enhances the security of the protocols. We investigate the security of the protocols against individual beam splitting attack.