Why Quantum Computers Cannot Work: The Movie!

Here are links to a videotaped lecture in two parts entitled “why quantum computers cannot work” recorded at the Simons Institute for the Theory of Computing on December 2013 and two additional videos: a short talk on topological quantum computers and a twelve minute overview.  Here are the links: OverviewPart IPart IITopological QC.  (Update, Nov 14: BosonSampling.)

Why Quantum Computers Cannot Work:

Overview and Vision.

Why Quantum Computers Cannot Work I:

From the “Trivial Flow” to Smoothed Lindblad Evolutions

Why Quantum Computers Cannot Work II:

Debate, Reasons to Disbelieve, and Experimentation

Why Topological Quantum Computers Cannot Work

The Geometry of Spacetime is Enabled by the Failure of Quantum Fault-Tolerance


Left: Nick Read; Right The front page of Nick’s 1990 famous paper with Greg Moore on nonabelions, and below his email to me from March 2005 on topological quantum computation. (click for full view.)


Left: the argument regarding topological QC demonstrated via Harris’ famous cartoon. While not strictly needed I expect the argument to extend from qubits to gates as well. Right: a recent discussion with Nick over Shtetl Optimized (click for full view). Update: We are actually not in an agreement as it seems from the above discussion (see the discussion below). 

Update (Nov’ 2014): A fifth video, this time in front of a live audience

Complexity and Sensitivity of Noisy BosonSampling

Update: A subsequent post by Steve Flammia, Quantum computers can work in principle over The Quantum Pontiff. (July:) See also this post: Quantum future” just beyond our grasp.

Added later (April 18): Let me quote from what Steve wrote about the videos: The surprising part is the superior production value relative to your typical videotaped lecture (at least for the first overview video). Producing the videos was an interesting and demanding experience and I was certainly happy to read Steve’s description of the production value.  (Of course, the main purpose of Steve’s post was to express his disagreement with the content of the videos. See either the post or Co-‘s comment below.) 

Also there are two earlier versions of my lecture (in 1-hour format) that were videotaped. The first was taken by Jesus De Loera in Davis. Very interesting shooting-angle and interesting comments by Greg Kuperberg, Bruno Nachtergaele and other participants.  The second was taken in Seattle in a UW-PIMS colloquium lecture. Again interesting questions by several participants including James Lee and John Sidles.

(July:) The Simons Institite (almost identical) versions of the movies are now linked from the web-page of my November 15 lecture at SI.

(Added nov 2014): The only difference from the HUJI version is that there are no opening slides and that for the closing slides I used two pictures of my department’s administrative staff.

es1  es2

The administrative crew of the Einstein Institite of Mathematics (click to enlarge)

I thought of it as a nice opportunity to thank our great administrative staff whose part is crucial  in the academic endeavor, and this is a good opportunity to thank the staff in my second academic home – Yale University, in the Simons Institute, in many other places.


Alistair Sinclair and the Simons Institure friendly and helpful staff (click for full size) 

Following Saharon Shelah: How to watch these videos

(Added Nov 2014)

Saharon Shelah explained in an introduction to one of his books, that instructions on “how to read this book” are actually instruction on “how to not read this book”. If you want to read the book you start on page 1 and read through to the last page.  Instructions for “how to read  this book” rather tell you how to jump to a place that interests you.

So, in a similar spirit, here are direct links to the different parts of the videos.

Continue reading