The Q# language from Microsoft is one of several ways to explore quantum computing. Two other ways are using the Qiskit library from IBM and the Cinq library from Google.

I first looked at Q# several years ago, but at that time, Q# was very rough and so I didn’t explore further, knowing that the language and its programming environment would change/improve. I make it a point to learn something new every day, and so, recently, one day before work, I figured I’d take another look at Q#. As usual, when getting started with something new, getting over the initial hurdle of installation and putting together a Hello World example, is a bit difficult. Briefly, 1.) I installed the Visual Studio Code program, 2.) installed the QDK (Azure Quantum Development Kit) extension for VSC, 3.) copy-pasted the code for a Quick Start demo I found online, and ran the demo.

Running the demo in VSC.

The Q# language is only supported on Visual Studio Code IDE, not the older Visual Studio IDE. I had recently updated VSC on my laptop to the latest version so I was good to go.

As far as I could tell, the QDK library can only be installed from within VSC, not as a standalone library. So I launched VSC, clicked on the funky Extension icon in the left margin, searched for Q#, and then installed Azure Quantum Development Kit from the list of results.

Installing the QDK from within VSC.

When I use the directory and file based VSC program, I usually prefer to create directories using the command line, rather than from within VSC. So, I launched a command shell and issued the commands:

cd \
cd VSM  (an existing directory)
md Quantum
cd Quantum
md HelloWorld
notepad Main.qs (to create the Q# program)

I closed Notepad. In VSC, I selected File | Open Folder and navigated to the newly created HelloWorld directory. I double-clicked on file Main.qs to load the empty file into the VSC editor.

I copy-pasted the following code into file Main.qs, which I found at learn.microsoft.com/en-us/azure/quantum/qsharp-quickstart:

import Microsoft.Quantum.Diagnostics.*;

operation Main() : (Result, Result) {  
  use (q1, q2) = (Qubit(), Qubit());
  H(q1);
  CNOT(q1, q2);
  DumpMachine();
  let (m1, m2) = (M(q1), M(q2));
  Reset(q1);
  Reset(q2);
  return (m1, m2);
}

I clicked on the Run item that’s weirdly placed within the editor. The output in the Debug Console was:

 Basis | Amplitude      | Probability | Phase
 -----------------------------------------------
  |00⟩ |  0.7071+0.0000𝑖 |    50.0000% |   0.0000
  |11⟩ |  0.7071+0.0000𝑖 |    50.0000% |   0.0000

(One, One)
Finished shot 1 of 1

Q# simulation completed.

OK, that went more smoothly than expected. I was satisfied with running the simulation on my local machine — I was not in the mood to try and run the program in the Azure cloud environment. I understand most of the demo program — creating qubits, the Hadamard operation, the Controlled Not operation, Measurement, and Reset — but there’s still a lot that I don’t entirely grok yet. I’ll save more investigation for another day.

Quantum computing is an exciting new field. I remember when DVDs first appeared in March of 1997. There’s a lot of contradictory information on the Internet about which were the first movie(s) released on DVD in the U.S. The general consensus is that “Twister” (1996) was the first, released in many cities on March 24, 1997. But there were about 32 other movies released on DVD in 1997, and because of the distribution chain, many of these early DVD titles appeared in cities in different orders.

Right: “The Fifth Element” (1997) is a wildly creative story that’s difficult to explain. Unlike the other two movies I list here, The Fifth Element was a big success financially, although critics didn’t like the movie too much. I have a tattoo related to this movie — there’s a long and mildly entertaining story about how and why I got the tattoo, especially considering the fact that I don’t like tattoos on me or anyone else. The story of my Fifth Element tattoo involves a teenage daughter — if you have ever been the father of a teenage daughter, you know they can bring joyful chaos into our particular multiverse.