Charles G. Peterson

Practical Free-Space Quantum Key Distribution over 1 km

A working free-space quantum key distribution system has been developed and tested over an outdoor optical path of {approximately}1 km at Los Alamos National Laboratory under nighttime conditions. Results show that free-space quantum key distribution can provide secure real-time key distribution between parties who have a need to communicate secretly. Finally, we examine the feasibility of surface to satellite quantum key distribution. {copyright} {ital 1998} {ital The American Physical Society}

Long-Distance Decoy-State Quantum Key Distribution in Optical Fiber

The theoretical existence of photon-number-splitting attacks creates a security loophole for most quantum key distribution (QKD) demonstrations that use a highly attenuated laser source. Using ultralow-noise, high-efficiency transition-edge sensor photodetectors, we have implemented the first version of a decoy-state protocol that incorporates finite statistics without the use of Gaussian approximations in a one-way QKD system, enabling the creation of secure keys immune to photon-number-splitting attacks and highly resistant to Trojan horse attacks over 107 km of optical fiber.

Free-space quantum-key distribution

Nonproliferation and International Security,Los Alamos, NM 87545(February 1, 2008)A working free-space quantum key distribution (QKD)system has been developed and tested over a 205-m indooroptical path at Los Alamos National Laboratory under fluo-rescent lighting conditions. Resultsshow that free-space QKDcan provide secure real-time key distribution between partieswho have a need to communicate secretly.PACS Numbers: 42.79.Sz, 03.65-w

Long-distance quantum key distribution in optical fibre

Use of low-noise detectors can both increase the secret bit rate of long-distance quantum key distribution (QKD) and dramatically extend the length of a fibre optic link over which secure keys can be distributed. Previous work has demonstrated the use of ultra-low-noise transition-edge sensors (TESs) in a QKD system with transmission over 50?km. In this study, we demonstrate the potential of the TESs by successfully generating an error-corrected, privacy-amplified key over 148.7?km of dark optical fibre at a mean photon number ? = 0.1, or 184.6?km of dark optical fibre at a mean photon number of 0.5. We have also exchanged secret keys over 67.5?km that is secure against powerful photon-number-splitting (PNS) attacks.

Practical long-distance quantum key distribution system using decoy levels

Quantum key distribution (QKD) has the potential for widespread real-world applications, but no secure long-distance experiment has demonstrated the truly practical operation needed to move QKD from the laboratory to the real world due largely to limitations in synchronization and poor detector performance. Here, we report results obtained using a fully automated, robust QKD system based on the Bennett Brassard 1984 (BB84) protocol with low-noise superconducting nanowire single-photon detectors (SNSPDs) and decoy levels to produce a secret key with unconditional security over a record 140.6 km of optical fibre, an increase of more than a factor of five compared with the previous record for unconditionally secure key generation in a practical QKD system.

Effects of propagation through atmospheric turbulence on photon statistics

The theory of the photon statistics of a beam propagated over a horizontal path in air is described and applied to the counting distribution and fade probability for weak laser pulses. Good agreement is obtained between theory and experiment for values of the refractive-index structure constant within an expected range and for various simplifying assumptions, including the assumption of a log-normal distribution for the fluctuations of the mean photon number due to atmospheric turbulence.

Demonstration of 1550 nm QKD with ROADM-based DWDM Networking and the Impact of Fiber FWM

We demonstrate compatibility of 1550 nm QKD with a MEMS-based ROADM and also show that four-wave mixing resulting from copropagating DWDM signals can become the dominant source of background noise within the QKD channel passband.

Quantum key distribution at telecom wavelengths with noise-free detectors

The length of a secure link over which a quantum key can be distributed depends on the efficiency and dark-count rate of the detectors used at the receiver. We report on the first demonstration of quantum key distribution using superconducting transition-edge sensors with high efficiency and negligible dark-count rates. Using two methods of synchronization, a bright optical pulse scheme and an electrical signal scheme, we have successfully distributed key material at 1550 nm over 50 km of optical fiber. We discuss how use of these detectors in a quantum key distribution system can dramatically increase range and performance.

Experimental characterization of the separation between wavelength-multiplexed quantum and classical communication channels

Quantum key distribution (QKD) is a new technique for secure key distribution based on the laws of physics rather than mathematical or algorithmic computational complexity used by current systems. Understanding the compatibility of QKD at 1310 nm with the existing commercial optical networks bearing classical wavelength-division-multiplexed (WDM) channels at 1550 nm is important to advance the deployment of QKD systems in such networks. The minimum wavelength separation for multiplexing QKD and WDM channels on a shared fiber is experimentally determined for impairment-free QKD+WDM transmission.

Impact of spontaneous anti-Stokes Raman scattering on QKD+DWDM networking

This study presents an experimental demonstration of 1310 nm QKD multiplexing and transmission with amplified DWDM signals over a shared 10 km fiber span. This work identifies anti-Stokes Raman scattering generated during fiber propagation as the primary contributor of crosstalk noise at the QKD receiver. New results are presented on the characterization of spontaneous anti-Stokes Raman noise (SASRN), generated within the fiber by the high-power DWDM signals, and implications for QKD+DWDM networking architectures are also discussed.