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 Quantum Information Networks

Diagram of quantum information network, including quantum channel and classical channel. See Overview below for description

News

Code for "Unbreakable" Quantum Encryption Generated at Record Speed over Fiber

(April 18, 2006) NIST scientists have developed a system for quantum key distribution which has demonstrated the exchange of cryptographic key at record speed. The system produced "raw" key at a rate of more than 4 million bits per second over 1 km of optical fiber. The system also worked successfully, although more slowly, over 4 km of fiber. The record speed was achieved with an error rate of only 3.6 percent, considered very low. The high speed of the system enables use of the most secure cipher known for ensuring the privacy of a communications channel, in which one secret key bit, known only to the communicating parties, is used only once to encrypt one data bit. Using this system, compressed video has been encrypted, transmitted and decrypted at a rate of 30 frames per second, sufficient for smooth streaming images, in Web-quality resolution, 320 by 240 pixels per frame.

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NIST physicist Xiao Tang and colleagues have developed a quantum communications system that uses single photons to produce a "raw" encryption key at the rate of 4 million bits per second.


Quantum Computers May Be Easier to Build Than Predicted

(March 3, 2005) A full-scale quantum computer could produce reliable results even if its components performed no better than today's best first-generation prototypes, according to a paper in the March 3 issue in the journal Nature by NIST mathematician Manny Knill. In that paper, Knill proposes a fault-tolerant architecture based on hierarchies of qubits and teleportation. Use of such an architecture could lead to reliable computing even if individual logic operations made errors as often as 3 percent of the time -- performance levels already achieved in NIST laboratories with qubits based on ions. The proposed architecture could tolerate several hundred times more errors than scientists had generally thought acceptable.

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The new NIST architecture for quantum computing relies on several levels of error checking to ensure the accuracy of quantum bits (qubits). The image above illustrates how qubits are grouped in blocks to form the levels. To implement the architecture with three levels, a series of operations is performed on 36 qubits (bottom row)?each one representing either a 1, a 0, or both at once. The operations on the nine sets of qubits produce two reliably accurate qubits (top row). The purple spheres represent qubits that are either used in error detection or in actual computations. The yellow spheres are qubits that are measured to detect or correct errors but are not used in final computations.


Quantum key distribution with 1.25 Gbps clock synchronization demonstrated

(May 3, 2004) We have demonstrated the exchange of sifted quantum cryptographic key over a 730 meter free-space link at rates of up to 1.0 Mbps, two orders of magnitude faster than previously reported results. A classical channel at 1550 nm operates in parallel with a quantum channel at 845 nm. Clock recovery techniques on the classical channel at 1.25 Gbps enable quantum transmission at up to the clock rate. System performance is currently limited by the timing resolution of our silicon avalanche photodiode detectors. With improved detector resolution, our technique will yield another order of magnitude increase in performance, with existing technology.

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Left: Physicist Joshua Bienfang sets up NIST quantum key distribution system. Photons encoding cryptographic keys are being sent in free space to the MIST Adminsitration Building shown in the background. (Photo by Gail Porter, NIST.) Right: Computer Scientists Alan Mink works on a programmable printed circuit board used to process data for the system in real time. (Photo ©Robert Rathe.)
Background
Quadchart executive summary
Overview what we are doing
Staff who we are
Reports X. Tang, L. Ma, A. Mink, A. Nakassis, H. Xu, B. Hershman, J. Bienfang, D. Su, R. F. Boisvert, C. Clark, and C. Williams, Demonstration of an Active Quantum Key Distribution Network, in Proceedings of SPIE -- Volume 6305, Quantum Communications and Quantum Imaging IV, (Ronald E. Meyers, Yanhua Shih, and Keith S. Deacon, Eds.), 630506, 6 pages, (August 2006).

L. Ma, H. Xu, and X. Tang, Polarization recovery and auto-compensation in Quantum Key Distribution network, in Proceedings of SPIE -- Volume 6305, Quantum Communications and Quantum Imaging IV, (Ronald E. Meyers, Yanhua Shih, and Keith S. Deacon, Eds.), 630513, 6 pages (August 2006).

D. J. Rogers, C. J. Bienfang, A. Mink, B. Hershman, A. Nakassis, X. Tang, L. Ma, D. H. Su, C. J. Williams, C. W. Clark, Free space quantum cryptography in the H-alpha Fraunhofer window, in Proceedings of SPIE -- Volume 6304, Free-Space Laser Communications VI, (Arun K. Majumdar and Christopher C. Davis, Eds.), 630417, 10 pages (September 2006).

H. Xu, L. Ma, J. C. Bienfang, and X. Tang, Influence of Avalanche-Photodiode Dead Time on the Security of High-Speed Quantum-Key Distribution Systems, CLEO/QELS, Conference Technical Digest CD-ROM: JTuH3.pdf, Long Beach, CA, May 21-26, 2006.

X. Tang, L. Ma, A. Mink, A. Nakassis, H. Xu, B. Hershman, J. C. Bienfang, D. Su, R. F. Boisvert, C. W. Clark, and C. J. Williams, Quantum Key Distribution System Operating at Sifted-key Rate Over 4 Mbit/s, in Proceedings of SPIE -- Volume 6244, Quantum Information and Computation IV, (Eric J. Donkor, Andrew R. Pirich, and Howard E. Brandt, Eds.), pp. 62440P-1-62440P-8 (May 2006).

A. Nakassis, J. C. Bienfang, P. Johnson, A. Mink, D. Rogers, X. Tang, and C. J. Williams, Has Quantum Cryptography Been Proven Secure?, in Proceedings of SPIE -- Volume 6244, Quantum Information and Computation IV, (Eric J. Donkor, Andrew R. Pirich, and Howard E. Brandt, Eds.), pp. 62440I-1-62440I-9 (April 2006).

A. Mink, X. Tang, L. Ma, A. Nakassis, B. Hershman, J. C. Bienfang, D. Su, R. Boisvert, C. W. Clark, and C. J. Williams, High Speed Quantum Key Distribution System Supports One-Time Pad Encryption of Real-Time Video, in Proceedings of SPIE -- Volume 6244, Quantum Information and Computation IV, (Eric J. Donkor, Andrew R. Pirich, and Howard E. Brandt, Eds.), pp. 62440M-1-62440M-7 (May 2006).

X. Tang, L. Ma, A. Mink, A. Nakassis, H. Xu, B. Hershman, J. C. Bienfang, D. Su, R. F. Boisvert, C. W. Clark, and C. J. Williams, Experimental study of high speed polarization-coding quantum key distribution with sifted-key rates over Mbit/s, Optics Express 14 No. 6, 2062-2070 (March 20, 2006).

E. Knill, Scalable Quantum Computing in the Presence of Large Detected-Error Rates, Physical Review A 71 042322/1-7, (also quant-ph/0312190).

D. Richard Kuhn, A Quantum Cryptographic Protocol with Detection of Compromised Server, Quantum Information and Computation 5, No. 7 (2005) 551-560.

Xiao Tang, Lijun Ma, Alan Mink, Anastase Nakassis, Barry Hershman, Joshua Bienfang, Ronald F. Boisvert, Charles Clark and Carl Williams, High Speed Fiber-Based Quantum Key Distribution using Polarization Encoding, Proceedings of SPIE 5893, Optics and Photonics Conference, San Diego, California, USA, July 31 - August 4, 2005.

Stephen S. Bullock, Dianne P. O'Leary, and Gavin K. Brennen, Asymptotically Optimal Quantum Circuits for d-level Systems, Physical Review Letters 94, 230502 (17 June 2005).

E. Knill, Quantum Computing with Very Noisy Devices, Nature 434 39-44, (also quant-ph/0410199), March 3, 2005.

Dianne P. O'Leary and Stephen S. Bullock, QR Factorizations Using a Restricted Set of Rotations, Electronic Transactions on Numerical Analysis, Volume 21, pp. 20-27, (2005).

Joshua C. Bienfang, Alex J. Gross, Alan Mink and Charles W. Clark, Quantum Cryptography Edges Toward Telecom Speeds and Practical Applications, Optics and Photonics News, December 2004, p. 38.

Gavin K. Brennen and Stephen S. Bullock, Stability of global entanglement in thermal states of spin chains, Physical Review A 70, 052303, November 4, 2004. Also: Virtual Journal of Quantum Information, Volume 4, Issue 11 (November 2004)

Vivek V. Shende, Stephen S. Bullock, Igor L. Markov, Recognizing Small-Circuit Structure in Two-Qubit Operators, Physical Review A 70 012310 (July 19,2004).

Vivek V. Shende, Stephen S. Bullock, and Igor L. Markov, A Practical Top-down Approach to Quantum Circuit Syntesis, quant-ph/0406176, July 2, 2004.

M. Ware and A. Migdall, Single Photon Detector Characterization using Correlated Photons: the March from Feasibility to Metrology, Journal of Modern Optics 51 (9-10) 2004, pp. 1549-1557.

J. C. Bienfang, A. J. Gross, A. Mink, B. J. Hershman, A. Nakassis, X. Tang, R. Lu, D. H. Su, Charles W. Clark, Carl J. Williams, E. W. Hagley and Jesse Wen, Quantum key distribution with 1.25 Gbps clock synchronization Optics Express 12 (9), May 3, 2004, pp. 2011-2016.

News Coverage "NIST Quantum Keys System Sets Speed Record for 'Unbreakable' Encryption" : Science Daily / Eurekalert / Supercomputing Online / Space Daily / Innovations Report / News.Nanoapex. "Quantum Cryptography Gets Up To Speed" : Science a GoGo. "Cryptographic System" : CCNews. "Quantum Cryptography Advance" : Encyclopedia of Computer Security.

S.S. Bullock and G.K. Brennen, Canonical Decompositions of n-qubit Quantum Computations and Concurrence, Journal of Mathematical Physics, vol. 45, issue 6, 2004, 2447-2467. Also Virtual Journal Nanoscale Sci. & Tech., Virtual Journal of Quant. Info., quant-ph/0309104

A. Nakasis, J. Bienfang and C. Williams, Expeditious Reconciliation For Practical Quantum Key Distribution, Proceedings of SPIE -- Volume 5436, Quantum Information and Computation II, Eric Donkor, Andrew R. Pirich, Howard E. Brandt, Editors, August 2004, pp. 28-35. Preprint

Paul E. Black and Andrew W. Lane, Modeling Quantum Information Systems, Proceedings of SPIE -- Volume 5436, Quantum Information and Computation II, Eric Donkor, Andrew R. Pirich, Howard E. Brandt, Editors, August 2004, pp. 340-347. Preprint

Isabel Beichl, Stephen Bullock, and Daegene Song, A Quantum Algorithm Detecting Concentrated Maps," April 23, 2004.

E. Knill, Fault-Tolerant Postselected Quantum Computation: Threshold Analysis, quant-ph/0404104, April 19, 2004.

Vivek V. Shende, Igor L. Markov, and Stephen S. Bullock, Finding Small Two-Qubit Circuits, Proceedings of the SPIE, QI&Cii, April 15, 2004.

Stephen S. Bullock and Gavin K. Brennen, Characterizing the entangling capacity of n-qubit computations, Proceedings of the SPIE, QI&Cii, April 13, 2004.

Stephen S. Bullock, Note on the Khaneja Glaser Decomposition, Quantum Information and Computation 4 (2004) 396-400.

E. Knill, Fault-Tolerant Postselected Quantum Computation: Schemes, quant-ph/0402171, February 23, 2004.

Stephen S. Bullock, Gavin K. Brennen, and Dianne P. O'Leary, Time Reversal and n-qubit Canonical Decompositions quant-ph/0402051, February 6, 2004.

E. Knill, Scalable Quantum Computation in the Presence of Large Detected-Error Rates, quant-ph/0312190, December 23, 2003.

Daegene Song, Remarks on Entanglement Swapping Journal of Optics B: Quantum and Semiclassical Optics 6 (January 2004) L5-L7.

Vivek V. Shende, Igor L. Markov, and Stephen S. Bullock, On Universal Gate Libraries and Generic Minimal Two-qubit Quantum Circuits, quant-ph/0308033, August 6, 2003.

Daegene Song, Secure Key Distribution by Swapping Quantum Entanglement, Physical Review A 69 034301 (March 5, 2004).

D. Richard Kuhn, Vulnerabilities in Quantum Key Distribution Protocols, quant-ph/0305076, May 14, 2003.

Daegene Song, Post-measurement Nonlocal Gates, quant-ph/0303147, March 24, 2003.

D. Richard Kuhn, A Hybrid Authentication Protocol Using Quantum Entanglement and Symmetric Cryptography, quant-ph/0301150, January 27, 2003.

Gavin K. Brennen, Daegene Song, and Carl J. Williams, A Quantum Computer Architecture using Nonlocal Interactions, Physical Review A (Atomic, Molecular, and Optical Physics) 67 (27 May 2003), 050302(R).

News Coverage "Quantum Bits Need to Catch a Virtual Bus" : NewsFactor / ACM TechNews
News Coverage "Quantum Computing Catches the Bus" : Technology Research News / ACM TechNews

A.L Migdall, D. Branning, and S. Castelletto, Tailoring Single and Multiphoton Probabilities of a Single-Photon On-Demand Source, Physical Review A 66, 053805 (2002).

Carl J. Williams, Xiao Tang, Mikko Heikkero, Julie Rouzaud, Richang Lu, Andreas Goedecke, Alan Migdall, Alan Mink, Anastase Nakassis, Leticia Pibida, Jesse Wen, Edward Hagley, and Charles W. Clark, A High Speed Quantum Communications Testbed, in Proceedings SPIE, International Symposium of Optical Science and Technology, July 2002.

A.L Migdall, D. Branning, S. Castelletto, and M. Ware, Single Photon Source with Individualized Single Photon Certifications, in Proceedings SPIE, International Symposium of Optical Science and Technology, July 2002.

Paul E. Black, Richard Kuhn, and Carl Williams, Quantum Computing and Communications, Advances in Computers, volume 56 (Marvin Zelkowitz, ed.), Academic Press, 2002, pp. 189-244.
Presentations Manny Knill, Introduction to Quantum Information, 2006.

Carl J. Williams, A High Speed Quantum Communications Testbed, International Symposium of Optical Science and Technology, Seattle, WA, July 2002.

Alan Migdall, Stefania Castelleto, and Michael Ware, Single Photon Source with Individualized Single Photon Certifications, International Symposium of Optical Science and Technology, Seattle, WA, July 2002.
Software C++ program for elementary quantum circuit synthesis demonstrating that any two-qubit quantum computation requires no more than 3 controlled-not's. (Developed by Stephen Bullock, November 2003)

C program for generating a quantum circuit to add two binary numbers of any width. (Developed by Paul Black, August 2003)

Opportunities Postdoctoral Research Program
Related Links
Portions of this work were supported by the DARPA Quantum Information Science and Technology (QuIST) Program
NIST Quantum Information Program: local context
Four Lectures on Quantum Computing, NSF Workshop on Coding Theory and Quantum Computing, University of Virginia, Samuel J. Lomonaco, Jr.
Samuel J. Lomonaco, Jr., ed., Quantum Computation. The Grand Mathematical Challenge for the Twenty-First Century and the Millennium, Proceedings of the Symposia of Applied Mathematics, American Mathematical Society, Providence, Rhode Island (2002).
Samuel J. Lomonaco, Jr. and Howard E. Brandt, eds., Quantum Computation and Information, AMS Contemporary Mathematics, Vol. 305, American Mathematical Society, Providence, RI (2002)
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Page created : 1 May 2001. Last update : 13 October 2006 by RFB.