Quantum computing and photon interference

What's in a name?
That which we call a rose
By any other name
Would smell as sweet.
- Shakespeare

The ideas of contravariance, and covariance, long of great utility in physics, were introduced into C# beginning with .Net Framework 3.5... At first glance there seems to be no relation between the physics and computer science usages...It might therefore be of interest to show the history of these ideas and how they found their way into the theory of computer languages...

The great Charles Townes (7/28/1915 - 1/27/2015) inventor of the maser/laser, celebrates a birthday this week.

When I was a kid, we had a neighbor whose job it was to translate Russian literature. This seemed to me at the time to be a rather peculiar job. German and French, sure, but Russian was not particularly popular. Why Russian? In retrospect, given that this was during the time of the cold war between the US and the USSR, it should have been obvious...

In keeping with the Russian/Ukrainian motif of the last two articles, here is a look back at Elton John's historic 1979 tour of Russia.

AS an undergraduate mathematics student, I had a topology professor who would tell his students about the early days of topology. There was it seemed a cafe where the Polish mathematicians would congregate anddiscuss mathematics for hours on end.

When some mathematician stumbled upon a problem or conjecture that was interesting but he could not solve, he could ask the coffee house staff for a book that was kept there just for the mathematicians...and in which the problem would be recorded as a challenge for any mathematician who visited the coffee house. From this cafe sprung many of the early results of topology and measure theory, and the book became rather famous, at least among topologists...

Well, it's a rather romantic story, but one that students tend to put aside as they concentrate on the job of actually learning the subject of topology!

But fast forward to the present -- and that cafe is now a bank...and that part of Poland is now Ukraine, and the Polish city of Lwow where the coffee house was located is now the Ukrainian city of Lviv ( 'Lvov/Lviv' translated from Russian/Ukrainian means 'Lion'. By the way, if you visit Lviv, you will discover many wonderful statues and sculptures, some quite old, of lions.)

Having visited Lviv a few times I have tended to concentrate on exploring the usual tourist attractions...but on a recent visit, I had to see if I could find this Scottish Cafe....

A while ago, Vladimir Putin was shown on Russian television cavorting around Kyzyl, Tuva. (The same Tuva after which Microsoft named its excellent Tuva Project). Tuva was made famous in the physics world in 1991 by the publication of 'Tuva or Bust, Richard Feynman's Last Journey'... At the time, the Tuva media attention caused me to dust off and re-read that book...leading, interestingly enough, to the discovery of a previously unknown, but unfortunately somewhat widely propagated, Feynman error. Yeah, Feynman published an error. So here is the story, along with my correction...

Recently, I talked to somebody who mentioned they had worked with coordinate systems and gimbals, which reminded me I have a backlog of old blog entries that have not been ported to .Net core... Here then is the port of an old post, on the great William Rowan Hamilton, quaternions, and gimbal lock...

The Wrath of Khan, Captain Kirk, and solving computer problems...

Linux and SQL Server

PostgreSQL and .NET Core

PostgreSQL and Digital Ocean...

React,Docker,and K8s...

Golang, built for Docker, k8s, and microservices....

K8s and microservices are the future of the enterprise...

Our ultimate goal is to explain, simply, how the classical idea of a bit -- something that can have a value of only zero or one -- may be extended to a quantum system. Because quantum mechanics uses 'complex numbers', it is natural to start there...

The quantum analog of a two valued sytem gives rise to the idea of a quantum bit, also known as a qubit.

Bits are familiar to many. Quantum bits (or qubits) are perhaps not so well known. They are neeeded for quantum computation, so we will take a look...

A standard text on computer graphics is 'Introduction to Computer Graphics' by Foley, Van Dam, Feiner, Hughes, and Phillips. Even though it was published...

This site has been converted to Angular 6

Sometime ago, NASA launched its Orion rocket, with the goal of sending man to Mars. A cost and benefit analysis is interesting...

A review of Dawkins' work that he wrote for a younger audience. A careful analysis of Dawkins' work is given. Dawkins' book utlimately turned out to be a missed opportunity for Dawkins.