Category Archives: Physics

Scientific Birthdays –Toffoli gate honored on namesake’s 70′th

Tommaso Toffoli’s 3-input 3-output logic gate, central to the theory of reversible and quantum computing, recently featured on a custom cake made for his 70′th birthday. Nowadays scientists’ birthday celebrations often take the form of informal mini-conferences, festschrifts without the … Continue reading

Posted in General, Physics, Quantum | 7 Comments

Resolution of Toom’s rule paradox

A few days ago our Ghost Pontiff Dave Bacon wondered how Toom’s noisy but highly fault-tolerant 2-state classical cellular automaton  can get away with violating the Gibbs phase rule, according to which a finite-dimensional locally interacting system, at generic points … Continue reading

Posted in General, Mathematics, Physics | 5 Comments

A Paradox of Toom's Rule?

Science is slow.  You can do things like continue a conversation with yourself (and a few commenters) that started in 2005.  Which is what I’m now going to do  The below is probably a trivial observation for one of the cardinals, … Continue reading

Posted in Physics | Leave a comment

4 Pages

Walk up to a physicist at a party (we could add a conditional about the amount of beer consumed by the physicist at this point, but that would be redundant, it is a party after all), and say to him or … Continue reading

Posted in Go Ahead, Waste Your Time, Off The Deep End, Physics, Quantum, The Loony Bin Called Academia | 4 Comments

Non-chaotic irregularity

In principle, barring the intervention of chance, identical causes lead to identical effects.  And except in chaotic systems, similar causes lead to similar effects.  Borges’ story “Pierre Menard” exemplifies an extreme version of this idea: an early 20′th century writer … Continue reading

Posted in Mathematics, Physics | Leave a comment

Test your intuition

The name of this post was shamelessly stolen from Gil Kalai’s popular series Test Your Intuition. But today’s post will be testing our physics intuition, rather than our mathematical intuition. Although this is a quantum blog, we’ll look at the … Continue reading

Posted in Physics, Puzzle, Science | 1 Comment

Throwing cold water on the Quantum Internet

There has been a lot of loose talk lately about a coming “Quantum Internet”. I was asked about it recently by a journalist and gave him this curmudgeonly answer, hoping to redirect some of the naive enthusiasm: …First let me … Continue reading

Posted in Physics, Quantum Computing, Quantum Cryptography, Science By Press Release, Technology | 5 Comments

Quantum Frontiers

As a postdoc at Caltech, I would often have lunch with John Preskill.  About once per week, we would play a game. During the short walk back, I would think of a question to which I didn’t know the answer. Then … Continue reading

Posted in Blogging, Caltech, Physics, Quantum | 1 Comment

What increases when a self-organizing system organizes itself? Logical depth to the rescue.

(An earlier version of this post appeared in the latest newsletter of the American Physical Society’s special interest group on Quantum Information.) One of the most grandly pessimistic ideas from the 19th century is that of  “heat death” according to … Continue reading

Posted in Computer Science, General, Mathematics, Physics, Science | 6 Comments

Why the laity hope Einstein was wrong.

Although reputable news sources pointed out that most scientists think some more mundane explanation will be found for the too-early arrival of CERN-generated neutrinos in Gran Sasso, recently confirmed by a second round of experiments with much briefer pulse durations … Continue reading

Posted in Astronomy, General, Physics, Teaching | 1 Comment