Quantum Computing, is it a Lottery?

I don’t profess to be an expert in quantum computing – in fact I am a quantum dummy, but I am also a very interested party. Unfortunately terms like superposition don’t really resonate with me (although I may take a guess at what they mean). The main thing I hear a lot about when it comes to quantum computing is that Qubits are like normal digital bits but they can have the values of 1 and 0 and every value in between all at the same time.

You may have heard of Schrödinger's cat which is used often as a way of describing quantum theory. However, for Quantum Computing, I don’t actually like this as an idea.  The cat, which is in a closed box is both alive and dead, and until you open the box (let the world interact with the cat) you don’t know what the reality is. Qubits are every possible value until you look at the result at which point you have the answer and in the case of the cat it is one of dead or alive. The point being that it has both states while you don’t look in the box. The reason I don’t like it is that there are only two states – dead or alive – and I think that in terms of quantum computing it actually makes it harder to understand because it plays to our digital world of one’s and zero’s and there is a tendency to think of two states as a result.

I was with some people the other day and we were chatting about quantum along with the ubiquitous cat and then randomly something was said by one of the attendees that made me sit up and think, “Wow! This is a great way of describing the possibility of all states and none all at the same time along with how observing the results destroys the experiment”

The something said was about lottery tickets. It was not about the ticket itself necessarily but about the dreams you have when you buy your ticket and before the numbers are chosen. It made me think that when you have your ticket in your hand you have in effect won any of the prizes from the smallest to the jackpot and none at all. Your dream of winning is actually the quantum state before the result is known because you don’t know if you have the jackpot, the smallest prize or nothing at all and until those numbers are drawn you could have won anything and everybody is dreaming they have won the jackpot. All possibilities at the same time until the result is observed. This is what I understand from quantum computing. 

The programmers are creating quantum “programmes” that generally explore all possibilities at the same time and the minute you “observe” the answer (the lottery balls have been chosen) you have “a” result. Now the reason I say “a” result is because that may not be the actual result that is the most probable, it is just one of many possible results (maybe I won £5, or £10, or the jackpot). We all know from experience that the most probable lottery result is actually to win nothing, and most of the people who bet on the lottery get exactly that – nothing. However, there is a relatively small minority who win prizes and if you picked a small number of players to talk to and they just happen to be winners you might assume that everybody always won something, and we know that isn’t true. So the key to Quantum computing is to run the programme many times (thousands) and from all the results see which one is the most probable (asking thousands of people how they had done on the lottery) – this is why quantum computing is made for problems that have many possible outcomes. On a classic computer this would take a long time to run through all the possibilities and then find out the answer, but on Quantum Computers it can do them all at the same time, many times and give you the most likely outcome.

For me this analogy helps me understand what is happening in a quantum computer. I hope it works for you too.