Related Links (no longer maintained-last updated Sep. 2006)
From the memorial
website of Richard Jeffreys
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,
"A Rudimentary Quantum Compiler (2cnd Ed.)", by R.R. Tucci,
"How to Compile A Quantum Bayesian Net", by R.R. Tucci,
"Quantum Information Theory - A Quantum Bayesian Net Perspective", by R.R.
"Quantum Computer as a Probabilistic Inference Engine", by R.R. Tucci,
"Binary Decision Diagrams are a Subset of Bayesian Nets", by R.R. Tucci,
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
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
"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.
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.
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
technologies that will change your world", MIT Tech Review Feb 2004.
This article talks about the work of Stanford Prof. Daphne Koller.
Nets Tutorial, maintained by Eugene Santos Jr.
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?
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 Pedagogical web articles, Lectures and Survey Papers:
Quantum Information Theory:
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:
See also book review by C. Bennett in Physics Today, February 99.
"Quantum Computing", by Jozef Gruska. The following web sites contain reviews
(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:
QC Patents :
Octave or Matlab m-files for QC programming
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.
list at Quantiki
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.
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.
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.
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,
"Classical model for bulk-ensemble NMR quantum computation", by R. Schack
and C. M. Caves,
"Good dynamics versus bad kinematics. Is entanglement needed for quantum
computation?", by N. Linden, S. Popescu,
"NMR spectroscopy and computing beyond myth and fiction", by Sergio De Filippo,
For more information about NMR computing, see
Ion Traps: NIST
Ion Storage Group has succeeded in doing error correction on 3 qubits.
Also of interest: "How to build a 300 bit, 1 Gop quantum computer"
Andrew M. Steane
Donor Atoms Precisely Implanted in Si:
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"
Cavity QED: The
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
Chang (Duke/Purdue) has entangled the spins of two quantum dots.
The Univ. of Wisconsin QC group has
a promising but yet untested QC design based on quantum dots. See
Josephson Junctions: D-Wave
Systems is a private Canadian company with many QC patents. Several other
groups (for example, a
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.
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
NMR computer can factor 15 (but you must first tell it
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
W. Unruh's QC opinions as voiced by him in various newsgroups (Prof.
Unruh is famous for his contributions to General Relativity)
QC Conference Lists:
QC Practitioners Lists:
QC Related Topics:
Donald Knuth (Wikipedia
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
(Classical) Reversible Computing
by R. Merkle. Quantum Computing and classical reversible computing have much
Classical Information Theory
Renormalization Group Techniques (their application to Information Theory)
Quantum Logic (Quantum Lattice Algebras)
"Consciousness, gravity and the quantum", An
interview with Sir Roger Penrose - Published in Network, May 2000
Interpretations of Quantum Mechanics
QC Sources of Government Funding
QC Grants and Contracts
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:
Other QC Link Lists