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Quantum Communication

Quantum information science combines two of the great scientific and technological revolutions of the 20th century, quantum mechanics and information theory. According to the National Science and Technology Councilís 2008 report ďA Federal Vision for Quantum Information ScienceĒ, quantum information science will enable a range of exciting new possibilities including: greatly improved sensors with potential impact for mineral exploration , improved medical imaging and a revolutionary new computational paradigm that will likely lead to the creation of computation device capable of efficiently solving problems that cannot be solved on a classical computer.

One of the fundamentally important research areas involved in quantum information science is quantum communications, which deals with the exchange of information encoded in quantum states of matter or quantum bits (known as qubits) between both nearby and distant quantum systems. Our Quantum Communication project performs core research on the creation, transmission, processing and measurement of optical qubits Ė the quantum states of photons, with particular attention to application to future information technologies.


Single photons at telecommunication wavelengths can be detected with higher efficiency with our frequency up-conversion detector.

In the past few years, we have undertaken an intensive study of quantum key distribution (QKD) systems for secure communications. Specifically, we demonstrated high-speed QKD systems that generate secure keys for encryption and decryption of information using a one-time pad cipher, and extended them into a 3-node quantum communications network. We have demonstrated the strengths and observed the limitations of QKD systems and networks. One such limitation is the effective communication distance of a point-to-point QKD system, which is about 100 km. Quantum repeaters represent a promising solution to this distance limitation. It enables quantum information exchange between two distant quantum systems including quantum computers. Though quantum repeaters are conceptually feasible, there are tremendous challenges to their development. Our goal in this area is to identify the problems, find potential solutions and evaluate their capabilities and limitations for future quantum communication applications.

In summary, we perform research and development (R&D) in quantum communication and related measurement areas with an emphasis on applications in information technology. Our R&D is aimed to promote US innovation, industrial competitiveness and enhance the nationís security. This website shows the footprint of our R&D efforts in the past few years.

For more information concerning this program, please contact project leader Dr. Xiao Tang (xiao.tang@nist.gov).

Keywords: quantum communication, quantum measurement science, entangled photons, quantum teleportation and repeaters, free space optics, quantum cryptography, photon source/detectors.

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Technical Developments
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Frequency Converter Enables Ultra-High Sensitivity Infrared Spectrometry:
Single photon level spectroscopy for the elusive infrared region has been demonstrated as part of ITLís Quantum Information Program. We have developed and demonstrated a new technology to measure the very low light (-126 dBm) spectra in the near infrared (IR) region using the frequency up-conversion technology developed previously.Read more here.
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NIST Quantum Cryptography Highlighted in New Journal of Physics:
Recent research has shown that the security of a key string of finite length can only be assured for key strings of relatively long lengths, and this understanding has underscored the importance of high-speed systems that maximize key production rates. The successful efforts at NIST in quantum information research are represented in two articles in the latest issue of the New Journal of Physics: Focus on Quantum Cryptography: Theory and Practice.Read more here.
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NIST Design Enables More Cost Effective Quantum Key Distribution:
ITL quantum communication research team have developed a new configuration for quantum key distribution (QKD) systems, in which the minimum number of single photon detectors needed is halved. The new configuration greatly simplifies the QKD structure and therefore reduced its cost.Read more here.
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ANTD and Security Division Colaborate to Investigate Integrating QKD into Networks.
ITL's Advanced Networking Division and Security Division are colaborating to investigate the problems and complexity of integrating Quantum Key Distribution (QKD) into existing network security protocols. Exisiting security protocols rely on public key exchange methods to distribute secure keys. When quantum computers are developed such key exchange mechanisms will be broken. Transitioning to future technologies, such as QKD, must be done well before such threats become reality.Read more here.
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Record key speed set by fiber QKD system at NIST:
A QKD system, built in ITL, produced quantum secure keys at a rate of more than 2 million bits per second (bps) over 1 kilometer (km) of optical fiber. This is a step toward using conventional optical fiber to distribute quantum crypto keys in local-area networks (LANs).Read more here.
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Three-User active QKD network developed by ITL researchers:
ITL researchers have developed a high speed active three-node QKD network, in which the QKD path can be routed by optical switches. Using this network, a QKD secured video surveillance system has been successfully demonstrated. Read more here.

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NIST QKD system at 1310 nm combines speed and distance:
NIST researchers developed a quantum key distribution system with photons being transmitted at 1310 nm, where fiber loss is small, and after wavelength conversion, being detected at 710 nm, where single photons can be detected with good performance. Read more here.

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Wireless QKD demonstrated by ITL and PL researchers:
Scientists from ITL and the Physics Labarotory tested a QKD by transmitting photons over free space between two NIST buildings that are 730 meters apart. Read more here.
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High-speed electronic control board makes NIST QKD system unique:
High-speed electronics boards for controlling the NIST QKD system were designed for both the key sender (Alice) and receiver (Bob). An FPGA on each board allows for complex parallel logic that is reprogramable providing a path for revisions and enhancements. Read more here.
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Low-noise frequency up-conversion single photon detector demonstrated by NIST:
Fiber loss is small around 1310 nm and 1550 nm. Single photons can be detected with good performance between 600 and 900 nm. The up-conversion, technology, developed by ITL, helps to solve this dilemma. Read more here.
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Error-correction software:
NIST computer scientists have developed a high-speed approach to error correction adapted from telecommunications techniques. This makes it possible to correct bit errors rapidly without time-consuming discussions between sender and receiver and without wasting key bits by revealing it to a potential eavesdropper. Read more here.
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Early Development:
Follow the various phases of the early development of the Quantum Information Networks project. Read more here.
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