Abstract:A secure communication network with quantum key distribution in a metropolitan area is reported. Six different QKD systems are integrated into a mesh-type network. GHz-clocked QKD links enable us to demonstrate the world-first secure TV conferencing over a distance of 45km. The network includes a commercial QKD product for long-term stable operation, and application interface to secure mobile phones. Detection of an eavesdropper, rerouting into a secure path, and key relay via trusted nodes are demonstrated in this network. ©2011 Optical Society of AmericaOCIS codes: (270.5568) Quantum cryptography; (060.5565) Quantum communications. References and links1. N. Gisin, G. Ribordy, W. Tittel, and H. Zbinden, "Quantum cryptography," Rev. Mod. Phys. 74(1), 145-195 (2002). 2. V. Scarani, H. Bechmann-Pasquinucci, N. J. Cerf, M. Dušek, N. N. Lütkenhaus, and M. Peev, "The security of practical quantum key distribution," Rev. Mod. Phys. 81(3), 1301-1350 (2009

Improvement in secure transmission of information is an urgent need for governments, corporations and individuals. Quantum key distribution (QKD) promises security based on the laws of physics and has rapidly grown from proof-of-concept to robust demonstrations and deployment of commercial systems. Despite these advances, QKD has not been widely adopted, and large-scale deployment will likely require chip-based devices for improved performance, miniaturization and enhanced functionality. Here we report low error rate, GHz clocked QKD operation of an indium phosphide transmitter chip and a silicon oxynitride receiver chip—monolithically integrated devices using components and manufacturing processes from the telecommunications industry. We use the reconfigurability of these devices to demonstrate three prominent QKD protocols—BB84, Coherent One Way and Differential Phase Shift—with performance comparable to state-of-the-art. These devices, when combined with integrated single photon detectors, pave the way for successfully integrating QKD into future telecommunications networks.

AKARI, the first Japanese satellite dedicated to infrared astronomy, was launched on 2006 February 21, and started observations in May of the same year. AKARI has a 68.5 cm cooled telescope, together with two focal-plane instruments, which survey the sky in six wavelength bands from mid–to far-infrared. The instruments also have a capability for imaging and spectroscopy in the wavelength range 2-180$\mu$m in the pointed observation mode, occasionally inserted into a continuous survey operation. The in-orbit cryogen lifetime is expected to be one and a half years. The All-Sky Survey will cover more than 90% of the whole sky with a higher spatial resolution and a wider wavelength coverage than that of the previous IRAS all-sky survey. Point-source catalogues of the All-Sky Survey will be released to the astronomical community. Pointed observations will be used for deep surveys of selected sky areas and systematic observations of important astronomical targets. These will become an additional future heritage of this mission.

Recently, the increasing availability of small-size satellites as well as low-cost launches is leading to a rapid growth in the number of satellite-constellation programs, in which thousands of satellites orbiting in a Low Earth Orbit (LEO) work in concert with each other for remote sensing and communications with coordinated ground coverage. Data-intensive satellite sensors mounted in such a constellation produce a large amount of information to be transmitted to the ground in a short time, which requires high capacity communications.However, conventional satellite communications based on microwave frequency bands will struggle to provide the needed capacity because these bands are already congested and severely regulated, and hence the frequency licensing process is lengthy. In the last decade, laser communication (lasercom) has evolved as a promising alternative for high-capacity data links from space [1-11], overcoming microwave communication in several key aspects, such as much higher data rates, being able to use an unregulated spectrum, ultra-low inter-channel interference, smaller and lighter terminals, and power-efficient transmission. In fact, the feasibility of satellite lasercom has been demonstrated by many space missions so far. However, they were based on dedicated bulky satellites of large size, typically several hundred kg with the lasercom terminal mass over 10 kg.Information security is also becoming an urgent issue in satellite constellations, because the amount of critical and valuable data to be communicated is increasing. Space quantum communication can enhance not

Integrated photonics has enabled much progress towards quantum technologies. Many applications, e.g., quantum communication, sensing, and distributed cloud quantum computing, require coherent photonic interconnection between separate on--chip subsystems. Large--scale quantum computing architectures and systems may ultimately require quantum interconnects to enable scaling beyond the limits of a single wafer, and towards multi--chip systems. However, coherently connecting separate chips remains a challenge, due to the fragility of entangled quantum states. The distribution and manipulation of entanglement between multiple integrated devices is one of the strictest requirements of these systems. Here, we report the first quantum photonic interconnect, demonstrating high--fidelity entanglement distribution and manipulation between two separate photonic chips, implemented using state--of--the--art silicon photonics. Path--entangled states are generated on one chip, and distributed to another chip by interconverting between path and polarization degrees of freedom, via a two--dimensional grating coupler on each chip. This path--to--polarization conversion allows entangled quantum states to be coherently distributed. We use integrated state analyzers to confirm a Bell--type violation of S=2.638±0.039 between the two chips. With further improvements in loss, this quantum photonic interconnect will provide new levels of flexibility in quantum systems and architectures.