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Project Mission  

To conduct quantum information related research to:
bulletProvide solutions for advanced quantum information science and technology to enhance US industrial competitiveness.
bulletDevelop and exploit new calibration and metrology techniques to achieve standardization in the area of quantum information and communication.
bulletProvide an infrastructure for quantum communication metrology, testing, calibration, and technology development.


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R&D 100 Award (2007)
R&D 100 award

IET Finalist Award (2007)
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DoC Silver (2008) and Bronze (2005) Medals
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ITL Outstanding Authorship (2007)
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Significant Publications

L. Ma, O. Slattery, and X. Tang, "Single photon frequency up-conversion and its applications", Physics Reports, (2012), doi:10.1016/j.physrep.2012.07.006 

Matthew T. Rakher, Lijun Ma, Oliver Slattery, Xiao Tang, Kartik Srinivasan, "Quantum Transduction of Telecommunications-band Single Photons from a Quantum Dot by Frequency Upconversion", Nature Photonics, 2010.

J.S. Pelc, Paulina S. Kuo, Oliver Slattery, Lijun Ma, Xiao Tang, and M. M. Fejer, "Dual-channel, single-photon upconversion detector at 1.3 um", Optics Express, Vol. 20, No. 17, 19075 (August 13, 2012).

Oliver Slattery, Lijun Ma, Paulina Kuo, Yong-Su Kim and Xiao Tang, “Frequency Correlated Bi-Photon Spectroscopy using a Tunable Up-Conversion Detector”, Laser Phys. Lett. 10, 075201 (July 2013).  http://iopscience.iop.org/1612-202X/10/7/075201

All Publications.

Quantum Communications

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 Council's 2008 report "A Federal Vision for Quantum Information Science", 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 – the quantum states of photons, with particular attention to application to future information technologies.

NIST up-conversion single photon detector is used to measure higher order temporal correlations of photons in near infrared region (view details in Projects and Developments). This picture shows a frame of a movie for the 4th order correlation function of the photons from a pseudo-thermal light source. (Click here to view the movie)

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 nation's security. This website shows the footprint of our R&D efforts in the past few years.

For more information concerning this program, please select link 'ITL Quantum Information Program' or contact project leader Dr. Xiao Tang at (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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Projects and Developments

Correlated Photon Pairs Are Used to Measure Spectra of Remote Objects


We have demonstrated a scheme for frequency correlated bi-photon spectroscopy using a strongly non-degenerate down-conversion source and a tunable up-conversion detector.  In this scheme, correlated signal and idler photon pairs are generated by spontaneous parametric down-conversion (SPDC).  The signal photons at one wavelength are used to interact with an object at a remote or inconvenient location.  The idler photons at another wavelength range, which had no interaction with the object, are then available for local spectral analysis using the upconversion detector and can be used to recreate the spectral function of the object.  Read more here. 

Can Noise In A Single-Photon Frequency Conversion Be Further Reduced?


We have demonstrated low-noise and efficient frequency conversion by sum-frequency mixing in a periodically poled LiNbO3 (PPLN) waveguide. We simultaneously achieve low noise (less than 600 counts per second) and high conversion efficiency (greater than 70%) by careful spectral filtering.  We compare different filtration schemes, including diffractive prisms, holographic transmission grating and a volume Bragg grating.  We discuss the impact of low-noise frequency translation on a single-photon upconversion detection and more generally for quantum information applications.  For more details, please read more in the article "Efficient, low-noise, single-photon-level conversion", Optics Letters Vol. 38, No. 8, 1310 (April 15, 2013) at: URL link here.

Surprising Conditions For Two-Photon Interference With Coherent Pulses


In many experimental demonstrations with optical pulses, classical and quantum interference are measured when pulses have temporal overlap at a beam splitter.  This often leads to a common misconception that classical and/or quantum interference requires the optical pulses to be temporally overlapping.  We study the conditions for two-photon classical interference with coherent pulses. This work finds that the temporal overlap between optical pulses is not required for interference.  However, coherence within the same inputs is found to be essential for the interference.  For more details, please read more in the article "Conditions for two-photon interference with coherent pulses" Phys. Rev. A 87, 063843 (2013) at: URL link here.

A Review Article About Single Photon Up-Conversion Technology is Published in 'Physics Reports'

'Physics Reports' journal published a review article, entitled "Single photon frequency up-conversion and its applications" in October 2012.  This paper summarizes the related pioneering research performed by our team in recent years and introduces its applications in quantum information, measurement science and other advanced research areas.  Read more here.

UpConversion Devices demonstrated to Work at Longer Wavelengths and Higher System Data Rates

 In collaboration with Stanford University, the NIST quantum communication group demonstrated single photon frequency up-conversion devices with longer wavelengths and higher system data rates than previously reported. Read more here.

Higher Order Temporal Correlations Measured using Up-Conversion Detector

The NIST quantum communications group has demonstrated an approach to measure the higher order (second-, third- and fourth) temporal correlations of photons in the near infrared (NIR) region using up-conversion detectors. The NIR photons are up-converted to the visible region and their  temporal correlations are then measured using silicon photodiodes. The experimental results reveal that the photon statistics are well preserved in the frequency up-conversion process. Read more here.

System data rate breaks the jitter limitation with NIST up-conversion detectors:  NISTs Quantum Communications research group has demonstrated a method to increase the date rate of quantum communication systems equipped with up-conversion detectors. The demonstration is implemented by using a novel multi-wavelength pumping scheme. Read more here.

NIST Up-Conversion Detector Achieves Ultra Low Noise Level: The ITL Quantum Communications research group recently published details showing significant performance improvements in frequency up-conversion technology. The group demonstrated an improved frequency up-conversion detector with ultra low dark count (i.e. noise). The dark count rate of this detector is lower than 100 counts/second at 10% detection efficiency. Read more here.


 Nature Photonics reports on ITL collaboration with CNST: Converting single photon emission from one wavelength to another is an important resource for integrating future quantum systems that combine low-loss optical transmission in the near-infrared with long-lived memories in the near-visible.  As described in an upcoming issue of Nature Photonics, a collaborative research effort from CNST and ITL has demonstrated frequency upconversion of single photons from a semiconductor quantum dot from the near-infrared to the near-visible.  Read more here.

Crystal WaveguideEntangled Photon Pair Sources: Entangled photon pairs are important for the realization of quantum communication and quantum computation. Our basic objective is to develop photon pairs that can interface between flying photonic qubits in optical fiber and stationary atomic qubits in quantum memories. As the fist step, we experimentally implemented a non-degenerate sequential time-bin entangled photon-pair source [1]. The second step, our effort is focused on to narrow down the spectral linewidth of the photon pairs so that they can be effectively interact with atoms in the quantum memory [2]. Read more here.

Upconversion detector for spectrometerFrequency Converter Enables Ultra-High Sensitivity Infrared Spectrometry: Single photon level spectroscopy for the elusive infrared region has been demonstrated as part of ITL’s 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.

journalphysicsNIST 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.

quant_cryptog_LR_smallNIST 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.

XiaoFiber-smallRecord 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.

1-Alice-2-Bobs-smallThree-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.

1310-system-smallNIST 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.

freespace-smallWireless QKD demonstrated by ITL and PL researchers: Scientists from ITL and the Physics Laboratory tested a QKD by transmitting photons over free space between two NIST buildings that are 730 meters apart. Read more here.

AlanBoard-smallHigh-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.

Upconversion-smallLow-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.

Tassos-small Error Correction Software Developed by NIST: 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.

phases_smallEarly Development: Follow the various phases of the early development of the Quantum Information Networks project. Read more here.