Let’s attempt some time travel. A few weeks back, I embarked on an experiment of learning about quantum computing in public. I started with a set of questions. Let’s see whether my slightly less ignorant current self can answer some of the questions of my completely ignorant past self.

How do quantum computers actually work? How do you do computation with qubits? How do you program a quantum computer?

I attempted to answer these questions in my deliberately boring article about quantum computing, but my one sentence version is: quantum computers execute algorithms using logic gates which operate on information encoded in the properties of entities at the quantum scale. I have also learnt that it’s very hard to write a meaningful one sentence version of quantum computing: better go read that article (or, even better, one of the resources linked at the end of this article).

Let’s get excited!

I started this series of articles about quantum computing because of the extravagant claims being made about the field. Those claims made me feel that I should be excited, but didn’t give me enough understanding to know why.

Last week I felt that I had made enough progress to give a dull but, I hope, useful account of quantum computing. So let’s revisit some of those extravagant claims and see how I feel about them now.

I won’t repeat my boring account of quantum computing here, but will give my one sentence version (as usual, if this is wrong, please correct me in the comments): quantum computing is the use of entities which exhibit the quantum properties of superposition and entanglement to represent mathematical properties and perform calculations.

Let’s be boring for a little while.

I’ve been trying to learn about quantum computing for the last few weeks and, while I am still only just getting started, I think that I have gained (with lots of help) a sufficient high level understanding to have a go at explaining some of the basics - at least in simple terms that I am capable of understanding.

One of the things I have found in investigating this field is that it very easy to fall prey to mystification. The behaviour of the world on a quantum scale is strange and counter-intuitive, and it is natural for our brains to keep screaming, ‘But what’s really happening?!’ However, I think that the best way for laypeople like me to get a basic understanding of quantum computing is to resist the temptation to over-visualise, to avoid mystical or mystifying language, and to keep analogies minimal and simple. In short, to follow Richard Feynman’s exhortation to ‘Shut up and calculate!’

Last week I shared that I was hitting a wall (made of maths) in my attempts to understand quantum computing, but that learning new things about the wonder and weirdness of the quantum world was keeping me going. This week I have to admit that I was rapidly running out of wonder, with a lot of wall still to climb.

Fortunately, some people came to my rescue! I have to thank Daniela Mordetzki for introducing me to her brother, Ariel Mordetzki, a researcher in quantum computing, to Ariel for taking the time to talk to me, and to my old colleague Michel Allair for taking the time to write and share notes on his own exploration of this field. Together, they helped me get a grip on concepts and explanations which had been eluding me. They also helped me to understand why all the books I am trying to read about quantum mechanics dive into the mathematics so early: at this stage in the maturity of quantum computing, the maths is what it’s all about.

This is going to take longer than I thought.

A couple of weeks back, I promised to do some learning in public, delving into a field I didn’t understand and sharing my experiences in this blog. I chose quantum computing. Last week I started by reading popular articles to gauge what an interested layperson could understand by scanning the press: I found some answers, but even more questions.

This week I tried to get serious: to read some books, as well as some detailed articles, summaries and links that some very kind friends and colleagues have sent me.

And, as things got serious, they started to get difficult. I found myself staring at pages of equations that made no sense to me, and terms that I didn’t understand. Have you ever had the experience of reading the same page of a book three times, and realising that nothing is going in? Or highlighting the sections that seem important and that you need to come back to - and then realising that you have highlighted everything? I’m at about that stage in my exploration of quantum computing.

Last week I promised to do some learning in public, to spend at least a few weeks attempting to get to grips with a subject I know little about: quantum computing.

The rules were that in the first week, I would only look at articles from the press, not written by specialists in the field, partly to introduce myself to the subject, but also to get a feel for how much a curious layperson can be expected to understand from such articles. In subsequent weeks, I will go deeper, reading specialist texts and, if possible, getting the advice of experts.

So, to follow my self-imposed rule, I started this week by opening up my browser, typing in ‘quantum computing’, selecting ‘news’, and reading the first half dozen or so articles.