If you’re reading a blog named ‘bits of quantum’, I guess I can assume you know a little bit about quantum computing and have a rough idea of what a qubit is. And, if you’ve read some of the previous articles on this blog, you may have gotten some idea of how difficult it is to make one. Being a quantum mechanic is real tough work, man!
Probably the largest challenge in quantum computing right now is minimizing the rate at which errors accumulate as you perform a computation on your quantum chip. In classical computers (your PC, or mobile phone), this is pretty much a solved problem. The probability of an error in any given operation is usually less than 1 in 1,000,000,000,000,000. This means in the process of me writing this blog post and it popping up on your screen probably less than one error has occurred. They’re not perfect, but after 50+ years of research and refinement, computers are pretty damn good these days.
So this post will be a bit more, let’s say, philosophical. I’d like to share some of my thoughts on a particular subject which has always struck me when I was studying physics and also now while I’m doing it in what might be called a professional fashion. That subject is mathematics. More precisely it is mathematics as applied to physics. Now I won’t pretend to be anything close to a real mathematician, but when you need a math-person and there are no mathematicians around you can probably do worse than a theoretical physicist. In physics, and also in computer science, we use math; a lot of it. In fact I would say that, and I think most physicists would agree with me, that mathematics is the language the universe is written in. Or at least the only language capable of describing it in an efficient manner. People often marvel at the ability of mathematics to capture physical phenomena in an extremely accurate and efficient manner, often waxing philosophically about the inherent simplicity of the universe. Here I’d like to give some of my, fragmented and incomplete, thoughts on the matter. While I certainly think that the fact that nature is describable at all is a fact worth pondering over long and hard I think the prevalence of math in physics and its remarkable effectiveness is at least partly due to decidedly more down to earth cultural forces present throughout the history of mathematics.
You have probably heard that entanglement is a very strong correlation way beyond anything we can conceive classically. However, as we’ve seen from Jeremy’s post , these strong correlations by itself do not allow us to send any information to the other part. So what can we use entanglement for?… To play games!
The general purpose programmable computer has been an enabling technology that has exceeded the original expectations in countless ways. From the humble beginnings of the original transistor, we now have devices that contain several billion transistors all working perfectly in unison in the smartphones we keep in our pocket. Our great hopes for the quantum computer are partially based on the belief that this could happen once again with the quantum computing paradigm.
The main challenge for realizing the quantum computer is certainly finding a suitable ‘quantum hardware’, that’s why it is still mainly a physics effort. However, it will also require a significant amount of computer programming and design. This makes our field interdisciplinary and soon computer scientists and engineers will likely play important roles in the further development of the quantum computer.
When people talk about physics, and in particular the human side of it, the ‘doing’ physics, they will usually point out that there exist two main forms of physicists. There are experimentalists, who spend their days gathering data in labs or tinkering with huge particle accelerators. These physicists, although rarely actually wearing white lab coats – at least in my experience – seem to be the closest to the pop culture stereotype of a scientist: wedding a strong analytical spirit to a practical, do-it-yourself mindset and a work ethic that often borders on obsession. They form the majority of physics practitioners and often speak with mild disdain about the ‘other’ type of physicist: the theorist. Theorists differ from experimentalist in that they mostly do, well, theory. Their days are usually not spent tinkering with equipment or analysing data but rather studying literature and diving into the complicated mathematics needed to describe modern physics. They often eschew the practical in favour of a generalist, axiomatic mindset; using as few assumptions as possible to describe the largest possible piece of the physical puzzle.
Throughout history these two strands of physics were usually not distinct professions but merely reflected the interests of a singular physicist. Even Newton, the prototype of a theoretical physicist, regularly performed experiments using prisms and even built one of the earliest reflecting telescopes. In my understanding of the history of physics these two strands of physicist started splitting into true professions in the late 19th century and early 20th century in response to the ever growing complexity of physics. Over time they grew further apart until the present day where among many theorists it is considered a point of pride to have never performed any experiments at all. Entire careers can be wholly devoted to the understanding of ‘physical theories’ that are decades away from being subjected to experimental verification. On the other hand, as the scale and complexity of experiments has grown, many experimentalists find themselves spending most of their time not doing physics but the cutting edge engineering work necessary to perform modern experiments to begin with. This has lead both groups to develop language and practices which differ immensely and can lead to almost Babylonic misunderstandings in the occasions where theorists and experimentalists do meet.