26 research outputs found
A high-speed multi-protocol quantum key distribution transmitter based on a dual-drive modulator
We propose a novel source based on a dual-drive modulator that is adaptable
and allows Alice to choose between various practical quantum key distribution
(QKD) protocols depending on what receiver she is communicating with.
Experimental results show that the proposed transmitter is suitable for
implementation of the Bennett and Brassard 1984 (BB84), coherent one-way (COW)
and differential phase shift (DPS) protocols with stable and low quantum bit
error rate. This could become a useful component in network QKD, where
multi-protocol capability is highly desirable.Comment: 15 pages, 7 figure
Free-running InGaAs single photon detector with 1 dark count per second at 10% efficiency
We present a free-running single photon detector for telecom wavelengths
based on a negative feedback avalanche photodiode (NFAD). A dark count rate as
low as 1 cps was obtained at a detection efficiency of 10%, with an afterpulse
probability of 2.2% for 20 {\mu}s of deadtime. This was achieved by using an
active hold-off circuit and cooling the NFAD with a free-piston stirling cooler
down to temperatures of -110C. We integrated two detectors into a
practical, 625 MHz clocked quantum key distribution system. Stable, real-time
key distribution in presence of 30 dB channel loss was possible, yielding a
secret key rate of 350 bps.Comment: 4 pages, 4 figure
Concise Security Bounds for Practical Decoy-State Quantum Key Distribution
Due to its ability to tolerate high channel loss, decoy-state quantum key
distribution (QKD) has been one of the main focuses within the QKD community.
Notably, several experimental groups have demonstrated that it is secure and
feasible under real-world conditions. Crucially, however, the security and
feasibility claims made by most of these experiments were obtained under the
assumption that the eavesdropper is restricted to particular types of attacks
or that the finite-key effects are neglected. Unfortunately, such assumptions
are not possible to guarantee in practice. In this work, we provide concise and
tight finite-key security bounds for practical decoy-state QKD that are valid
against general attacks.Comment: 5+3 pages and 2 figure
2.23 GHz gating InGaAs/InP single-photon avalanche diode for quantum key distribution
We implement an InGaAs/InP single-photon avalanche diode (SPAD) for
single-photon detection with the fastest gating frequency reported so far, of
2.23 GHz, which approaches the limit given by the bandwidth of the SPAD - 2.5
GHz. We propose a useful way to characterize the afterpulsing distribution for
rapid gating that allows for easy comparison with conventional gating regimes.
We compare the performance of this rapid gating scheme with free-running
detector and superconducting single-photon detector (SSPD) for the coherent
one-way quantum key distribution (QKD) protocol. The rapid gating system is
well suited for both high-rate and long-distance QKD applications, in which
Mbps key rates can be achieved for distances less than 40 km with 50 ns
deadtime and the maximum distance is limited to ~190km with 5 s deadtime.
These results illustrate that the afterpulsing is no longer a limiting factor
for QKD.Comment: 8 pages, 7 figures, submitted to Proceedings of SPI
Quantum Metropolitan Optical Network based on Wavelength Division Multiplexing
Quantum Key Distribution (QKD) is maturing quickly. However, the current
approaches to its application in optical networks make it an expensive
technology. QKD networks deployed to date are designed as a collection of
point-to-point, dedicated QKD links where non-neighboring nodes communicate
using the trusted repeater paradigm. We propose a novel optical network model
in which QKD systems share the communication infrastructure by wavelength
multiplexing their quantum and classical signals. The routing is done using
optical components within a metropolitan area which allows for a dynamically
any-to-any communication scheme. Moreover, it resembles a commercial telecom
network, takes advantage of existing infrastructure and utilizes commercial
components, allowing for an easy, cost-effective and reliable deployment.Comment: 23 pages, 8 figure
Sine gating detector with simple filtering for low-noise infra-red single photon detection at room temperature
We present and analyze a gated single photon avalanche detector using a sine
gating scheme with a simple but effective low-pass filtering technique for fast
low-noise single photon detection at telecom wavelength. The detector is
characterized by 130 ps short gates applied with a frequency of 1.25 GHz,
yields only 70 ps timing jitter and noise probabilities as low as 7E-7 per gate
at 10% detection efficiency. We show that the detector is suitable for high
rate quantum key distribution (QKD) and even at room temperature it could allow
for QKD over distances larger than 25 km.Comment: 6 pages, 11 figure
Distribución cuántica de claves en redes de acceso WDM-PON
En esta comunicación se plantea el estudio de redes para QKD donde sólo coexisten canales cuánticos compartiendo la misma fibra. Se han estudiado las redes de acceso basadas en la tecnología WDM-PON y DWDM (Dense WDM) en red central, lo que permitiría el direccionamiento mediante longitud de onda y abaratar la tecnología al compartir un solo sustrato físico, idéntico al usado en redes de telecomunicación, entre multitud de canales cuánticos. Además, hemos comprobado su funcionamiento de forma experimental en el laboratorio con equipos comerciales. En un futuro habrá que estudiar el comportamiento de los distintos componentes de la red y la compatibilidad de los distintos dispositivos QKD para integrarse dentro de un canal compartido en la misma red cuántica
Proposal for a Wavelength Multiplexed Quantum Metropolitan Area Network
Quantum Key Distribution (QKD) is maturing quickly. However, the current approaches to its network use require conditions that make it an expensive technology. All the QKD networks deployed to date are designed as a collection of dedicated point-to-point links that use the trusted repeater paradigm. Instead, we propose a novel network model in which QKD systems use simultaneously quantum and conventional signals that are wavelength multiplexed over a common communication infrastructure. Signals are transmitted end-to-end within a metropolitan area using optical components. The model resembles a commercial telecom network and takes advantage of existing components, thus allowing for a cost-effective and reliable deployment
Quantum metropolitan optical network based on wavelength division multiplexing
Quantum Key Distribution (QKD) is maturing quickly. However, the current approaches to its application in optical networks make it an expensive technology. QKD networks deployed to date are designed as a collection of point-to-point, dedicated QKD links where non-neighboring nodes communicate using the trusted repeater paradigm. We propose a novel optical network model in which QKD systems share the communication infrastructure by wavelength multiplexing their quantum and classical signals. The routing is done using optical components within a metropolitan area which allows for a dynamically any-to-any communication scheme. Moreover, it resembles a commercial telecom network, takes advantage of existing infrastructure and utilizes commercial components, allowing for an easy, cost-effective and reliable deployment
Multiplexing QKD systems in Conventional Optical Networks
Current QKD designs try to keep the quantum channel as error free as possible by using a separate physical medium for this purpose. In the most common case, this means the exclusive use of an optical fiber for the quantum channel, precluding its use for any other purpose. In current optical networks, the fiber is the single most expensive element and this poses a major problem from a cost and availability point of view. Sharing the fiber is thus mandatory for the widespread adoption of QKD. The objective of this communication is to propose a general scheme and present some preliminary measurements of a metropolitan area network (MAN) designed to multiplex of the order of 64 addressable quantum channels and the associated QKD classical service signals on a single dark fibre. It uses as much existing components and infraestructure as possible in an attempt to simultaneously lower most of the practical barriers for the adoption of QKD