Related Links (no longer maintained-last updated Sep. 2006)

(by rrtucci)

From the memorial website of Richard Jeffreys

Electronic Libraries

• arXiv (Los Alamos/Cornell) e-print library Most physicists submit their papers to this electronic library before (or after or instead of) submitting them to a journal.
• quant-ph subset of arXiv Most Quantum Computing papers are in this subset of arXiv
• NetLib, primarily a library of software packages. It contains, for example, LAPACK (Linear Algebra Package), a priceless resource for writing quantum compilers.

Technical Papers about Quantum Bayesian Nets:

• "Quantum Bayesian Nets", by R.R. Tucci, quant-ph/9706039
• "A Rudimentary Quantum Compiler (2cnd Ed.)", by R.R. Tucci, quant-ph/9902062
• "How to Compile A Quantum Bayesian Net", by R.R. Tucci, quant-ph/9805016
• "Quantum Information Theory - A Quantum Bayesian Net Perspective", by R.R. Tucci, quant-ph/9909039
• "Quantum Computer as a Probabilistic Inference Engine", by R.R. Tucci, quant-ph/0004028
• "Binary Decision Diagrams are a Subset of Bayesian Nets", by R.R. Tucci, quant-ph/0209009
• click here to search the arXiv eprint library for all papers with "(bayesian AND net*) AND quantum" in their abstract

Classical Bayesian Nets, Bayesianism

• Newspaper and Magazine Articles:
  • "Improbable Inspiration" (by Leslie Helm, LA Times, Oct 28, 1996). According to this article, Microsoft Office uses (classical) Bayesian Nets to implement some of its help features, such as Clippy, the intrusive paper clip.  
  • More recently (2001), Microsoft has launched a vast publicity campaign around Clippy's obnoxious charm. Furthermore, the much ballyhooed (and widely dreaded) dotNET and XP Microsoft initiatives will have some Bayesian net underpinnings. You can read about this in Business Week. Other magazine articles describing the growing use of Bayesian nets in Microsoft software can be found by descending into the dragon's lair.
  • "The Quest for Meaning" (by Steve Silberman, Wired Magazine, Feb. 2000, page 173) This article tells about a highly successful British company called Autonomy that makes trainable, pattern recognizing computer programs based on (classical) Bayesian nets. The article claims that Microsoft has 25 people working on similar programs.
  • "Adding Art to the Rigor of Statistical Science" (by David Leonhardt, New York Times, April 28, 2001).
  • "A Plan for Spam", by Paul Graham. How to design a Spam filter based on Bayes rule. Why Bayes rule may save us from the spam plague.
  • "18th-century theory is new force in computing" (by Michael Kanellos, CNET News.com, February 18, 2003) Besides Microsoft and Autonomy, Google and Intel are now avid users and advocates of Bayesian techniques.
  • "Intel to release machine learning libraries", 02 May 2003 New Scientist, "Intel says "read my lips" with open source software that predicts users' needs", 9 Dec 2003, DeviceForge.com
  • "Ten emerging technologies that will change your world", MIT Tech Review Feb 2004. This article talks about the work of Stanford Prof. Daphne Koller.
• Bayesian Nets Tutorial, maintained by Eugene Santos Jr.
• Very nice Bayesian Nets site maintained by Kevin Murphy
• A frequently asked question is: What is the best way to begin to learn about quantum Bayesian nets? We recommend that you first learn about classical Bayesian nets. It is fun, and highly instructive. Download a demo of any classical Bayesian net computer program, and play with it. That is how we started, with one of the very first Bayesian net programs for the Mac, a program called Ergo (nowadays, many others are available). Then ask yourself, how would I design an analogous computer program for doing quantum mechanics? Since classical probability is in some sense a subset of (or parallel to) quantum mechanics, it should be possible to calculate a probability predicted by quantum mechanics for each probability predicted by classical probability and classical Bayesian nets. Right? Here is K. Murphy's list of classical Bayesian nets software.
• Bayesians Laboring In Physics (BLIP), a list of web sites by persons who use Bayesian techniques in the physical sciences.
• Judea Pearl web site. Pearl is one of the pioneers of classical Bayesian nets. His website has some good pedagogical materials. Go there if you are interested in learning how to describe causality using Bayesian nets and other tools, how to distinguish causality from mere correlation, and how to use causality once you have established its existence.

(QC=Quantum Computing)

QC Pedagogical web articles, Lectures and Survey Papers:

• Beginner Level
  • Wikipedia articles on Quantum Information
  • Quantiki
  • "From Cbits to Qbits: Teaching computer scientists quantum mechanics", by David Mermin, quant-ph/0207118
  • "An Introduction to Quantum Computing for Non-Physicists", by Eleanor Rieffel and Wolfgang Polak, quant-ph/9809016.
• Intermediate Level
  • "Quantum Computing", by Andrew Steane, quant-ph/9708022.
  • CS483 (Cornell) by David Mermin
  • PHYS/EEE 532 (Bilkent U, Turkey) byA. Shumovsky and E. Arikan
  • M743 (Indiana University) by Zdzisaw Meglicki
• Advanced Level
  • Physics 219 (Caltech) by John Preskill
  • qip Courses at Uni of Waterloo by Cleve, Mosca, Gottesman, etc (Uni of Waterloo close to Perimeter Institute)
• Quantum Information Theory:
  • Schumacher lectures
  • IEEE review article by Bennett, Shor.
  • "Capacities of Quantum Channels and How to Find Them", by P. Shor, quant-ph/0304102
  • "Quantum Information Theory - A Quantum Bayesian Net Perspective", by R.R. Tucci, quant-ph/9909039
  • "The Role of Relative Entropy in Quantum Information Theory", by V.Vedral, quant-ph/0102094
• QC Paulinesia, quant-ph/0407215 by Robert Tucci.  An archipelago of identities, formed from the lava of Pauli Matrices, by the volcanic activity of Quantum Computing.
• The Quantum Fog application  includes a book in pdf format.

QC Paper Books

• "Explorations in Quantum Computing", by Colin P. Williams and Scott H. Clearwater. This book has received mixed reviews. The following web sites contain reviews of it: Amazon.com. See also book review by C. Bennett in Physics Today, February 99.
• "Quantum Computing", by Jozef Gruska. The following web sites contain reviews of it: Amazon.com, Amazon.co.uk (this is the semi-autonomous British branch of the US namesake)
• "Quantum Computation and Quantum Information", by Michael A. Nielsen, Isaac L. Chuang. This book has received mixed reviews. The following web sites contain reviews of it: Amazon.com, Amazon.co.uk

QC Patents :

• Patents in Quantum Computing, a web page of the Artiste Company

QC Software:

• quantum compilers:
  • Qubiter. Free, C++ source code
• Octave or Matlab m-files for QC programming
  • M-fun for QC Progs
• quantum computer simulations: There are several QC sims available, but only Quantum Fog uses the Quantum Bayesian Net approach. We prefer this approach and hold a patent for its use. However, we recommend that you compare the B. Net approach with other approaches and form your own opinion.
• QC software list at Quantiki

QC Hardware:

At present, there is no adequate experimental realization of even a 5 bit quantum computer. However, experiments currently being done in the following areas could lead to such a device.

• NMR: There are at least 3 very serious problems with this approach.
  1. With an NMR computer, measuring (initializing, reading) the state of a single qubit is not possible. One can only measure the average of a quantity over an ensemble of qubits.
  2. NMR computers using liquid samples at room-temperature cannot be scaled easily to more than about 10 qubits because the sample's signal decreases exponentially with qubit number. One can increase the strength of the signal by using solid samples at low temperatures, but then dipole-dipole interactions between the nuclear spins must be included in the theory. These dipole-dipole interactions average out to zero for liquid samples at room-temperature. Dipole-dipole interactions make NMR Theory for solid samples much less tractable than for liquids. Hence, NMR computers are most probably a dead-end street in the path of increasing qubit number.
  3. For a while, NMR computers using liquid samples at room-temperature seemed promising in the 2 to 10 qubit range, but then several well respected scientists proved in the following papers that such computers are too noisy to produce quantum entanglement. Quantum entanglement is widely believed to be one of the main reasons why quantum computers can outperform classical computers.
     • "Separability of very noisy mixed states and implications for NMR quantum computing", by S.L. Braunstein, C.M. Caves, R. Jozsa, N. Linden, S. Popescu, R. Schack, quant-ph/9811018
     • "Classical model for bulk-ensemble NMR quantum computation", by R. Schack and C. M. Caves, quant-ph/9903101
     • "Good dynamics versus bad kinematics. Is entanglement needed for quantum computation?", by N. Linden, S. Popescu, quant-ph/9906008
     • "NMR spectroscopy and computing beyond myth and fiction", by Sergio De Filippo, quant-ph/9911015

  For more information about NMR computing, see

  • "What really gives a quantum computer its power?", Physics Today, Jan. 2000.
  • "Quantum Computing and Nuclear Magnetic Resonance", quant-ph/0106067, a nice review article by J.A. Jones
• Ion Traps: NIST Ion Storage Group has succeeded in doing error correction on 3 qubits. See quant-ph/0102086 and quant-ph/0212079

  Also of interest: "How to build a 300 bit, 1 Gop quantum computer" quant-ph/041216 by Andrew M. Steane

• Donor Atoms Precisely Implanted in Si: Semiconductor Nanofabrication Facility (University of New South Wales, Sydney, Australia) has an impressive research program and multiple patents. See "Oz Trouncing US in Race for a Quantum Computer", and "The Kane Computer" (Wikipedia article)
• Cavity QED: The QUIC project at Caltech was awarded a 5 year, 5 million dollar grant by DARPA in Sept. 1996 to build a prototype quantum computer using cavity QED (Quantum Electro Dynamics). Since then, QUIC hasn't reported any significant progress in constructing such a device so it appears that they have encountered unsurmountable difficulties.
• Quantum Dots: Albert Chang (Duke/Purdue) has entangled the spins of two quantum dots. See cond-mat/0305289. The Univ. of Wisconsin QC group has a promising but yet untested QC design based on quantum dots. See cond-mat/0208021
• Josephson Junctions: D-Wave Systems is a private Canadian company with many QC patents. Several other groups (for example, a Riken/Nec/SUNYStonybrook collaboration) are also pursuing qubits based on Josephson Junctions. Should be an interesting horse race.
• Topological quantum computer (TQC): Such QCs encode qubits into quantum excitations that are subject to topological constraints, and take advantage of these topological constraints to protect  the QC calculation from decoherence. A particular type of TQC would use anyons. Some of the persons associated with this scheme are Kitaev and Preskill from Caltech, Freedman from Microsoft. No experimental results in TQC so far. (Quantum Fog and Qubiter apply to this type of QC also).

For an overview of QC hardware requirements, see this paper by D.P. DiVincenzo

QC Opinions

• Feynman's views on the challenge of objectivity in science
• "What really gives a quantum computer its power?", Physics Today, Jan. 2000. This must-read article presents the views of  many  important QC researchers about the relationship between quantum computing and NMR computing. 
• Feasibility of Shor's Algorithm in serious doubt.
• Chuang's NMR computer can factor 15 (but you must first tell it the answer)
• Prof. Leonid Levin's QC Opinions (Prof. Levin is famous for his contributions to Complexity Theory. Here is a quote from a pdf document entitled "A Short History of Complexity", by L. Fortnow and S. Homer:

  The existence of NP-complete problems was proved independently by Stephen Cook in the United States and Leonid Levin in the Soviet Union. Cook, then a graduate student at Harvard, proved that the satisfiability problem is NP-complete [Coo71]. Levin, a student of Kolmogorov at Moscow State University, proved that a variant of the tiling problem is NP-complete [Lev73]... In the following years, and continuing until today, literally thousands of problems have been shown to be NP complete. A proof of NP-completeness has come to signify the (worst case) intractability of a problem. Once proved NP-complete, researchers turn to other ways of trying to solve the problem, usually using approximation algorithms to give an approximate solution or probabilistic methods to solve the problem in "most" cases.

• "Grover Semantics for Non-Experts"
• "Oz Trouncing US in Race for a Quantum Computer"
• drawbacks of quantum cryptography
  • "Quantum Key Distribution: Advanced Technology But Few Applications" by Ray Wagner, Nov.7, 2002. This is a report by Gartner Research (a respected business research firm) about the commercial prospects of quantum cryptography. MagiQ Technologies, ID Quantique and BNN Technologies are 3 companies trying to sell this product.
  • "Why Quantum Cryptography?" by K. Paterson, F. Piper, R. Schack, quant-ph/0406147
• Prof W. Unruh's QC opinions  as voiced by him in various newsgroups (Prof. Unruh is famous for his contributions to General Relativity)

QC Humor

• The QComp Onion, America's Finest News Source about Quantum Computation
  • Issue 1, January 2002
• D-Wave Systems' (Gordie Rose) patent application for all Integrated Development Environments for quantum computers. Next, those brainiacs are going to invent a molecule with two hydrogen and one oxygen atoms.
• Microsoft's (Lucius G. Meredith)  patent application for almost all quantum computer software
• (Keep in mind that according to my dictionary: counterfactual  adj. not reflecting or taking into account the facts) Now look at what some quantum computerists call Counterfactual Computing
  • "Suppose that we are given a quantum computer programmed ready to perform a computation if it is switched on. Counterfactual computation is a process by which the result of the computation may be learnt without actually running the computer." first 2 sentences from abstract of quant-ph/9907007
  • "A quantum computer can solve problems even without being switched on", Nature Mag., 2 May 2001 (And an emperor can dress himself even without putting his garments on?)
• A press release from MIT, just received here at Reuters: MIT Hosting Quantum Computing Toga Party
• A Petition to the American Physical Society for the Creation of a New Acronym
• a parody of Ya Got Trouble (from The Music Man)
• MIT Media Lab
  • NY Times article
  • Voodoo Magazine article

QC Conference Lists:

• Daniel Lidar's List

QC Practitioners Lists:

• Who's Who page at Quantiki

QC Related Topics:

• Entanglement
  • Squashed Entanglement (Wikipedia article)
• Donald Knuth (Wikipedia article)
• Complexity Theory

  I recently contributed this comment to "Qubit News": "If complexity theorists had been entrusted with the task of building modern digital computers, they would still be writing papers about the amazing complexity issues of the abacus". This just about sums up my feelings about complexity theorists. Sure, I believe that given two algorithms, say quicksort and bubblesort, we should count the number of basic steps in each to decide which one is faster asymptotically. But do I care about the 400+ complexity classes in Scott Aaronson's Complexity Zoo website? nope

• Binary Decision Diagrams
  • Website of Randal Bryant, inventor of BDDs
  • "An Introduction to Binary Decision Diagrams", by Henrik Reif Andersen. Available at Andersen's website
  • "Binary Decision Diagrams are a Subset of Bayesian Nets", by R.R. Tucci, quant-ph/0209009
  • Dave Greve's application of BDD to quantum computing
• (Classical) Reversible Computing
  • Reversible Logic, by R. Merkle. Quantum Computing and classical reversible computing have much in common.
• Nanotech
  • Nanotechnology, by R. Merkle. At Merkle's site, you will find: There's Plenty of Room at the Bottom: An Invitation to Enter a New Field of Physics, by R. P. Feynman. This is a transcript of the classic 1960 talk that started the field of nanotechnology.
• Classical Information Theory
  • Claude Shannon (Wikipedia article)
  • Shannon day at Bell Labs. This web site includes "A Mathematical Theory of Communication", by Claude Shannon-- the 1948 paper that took the field of Information Theory and instantly transformed it from an embryo to a mature adult.
  • Website of Prof. Thomas M. Cover, author of an excellent book on Classical Information Theory.
• Renormalization Group Techniques (their application to Information Theory)
  • WimpyRG
• Quantum Logic (Quantum Lattice Algebras)
  • Quantum Logic (Wikipedia article)
  • A Half Century of Quantum Logic--What Have We Learned? by D.J. Foulis. This 1995 paper is an excellent introduction to the field of Quantum Logic by one of its main contributors.
  • Quantum Logic : Order Structures in Quantum Mechanics, by M. Ziegler
• "Consciousness, gravity and the quantum",  An interview with Sir Roger Penrose - Published in Network, May 2000
• Interpretations of Quantum Mechanics
  • Interpretation of Quantum Mechanics (Wikipedia article)

QC Sources of Government Funding

(in U.S.)

• ARO
• DARPA
• DTO (formerly called ARDA, no website , Wikipedia description)
• NSF
• SBIR

QC Grants and Contracts

(in U.S.)

Find out how your research dollars are being spent. For each grant or contract, get: name of investigators, their university or company, a description of their goals, how much money was awarded, duration of grant, etc. Unfortunately, ARO and DARPA, two prime funders of quantum computing, do not publish such information on the web (as of Oct 31, 2003)

• NSF Award Search Excellent website. Insert "quantum computer" OR "quantum computers"

QC Newsgroups, Mailing Lists, Blogs:

• Qubit News

  Some of my contributions to it:

  • Biography of Donald Knuth
  • There are Bayesians Amidst Us!
  • Bill Unruh, good referee
  • U.S. Quantum Computerists Headed for Bread Lines
  • QC Programming Puzzler
• Blogs
  • Quantum Pontiff
• sci.physics  For general physics questions. (Available via a news server or Google Newsgroups)
• sci.physics.research (moderated) For general physics questions. (Available via a news server or Google Newsgroups)
• bayes-news@stat.cmu.edu  For announcing events and news related to Bayesian nets. To subscribe:
  • Send a message to: majordomo@stat.cmu.edu
  • Body of the message: subscribe  bayes-news  your_email_address

Other QC Link Lists

• Ian Glendinning's QC Hotlist
• dmoz.org, section on quantum computing