Quantum computers are here...
Quantum computing is one of those technologies that seems forever just over the horizon, much like the flying car or an iPhone that lasts all day on a single charge. Developments come and go, announcements are made, each sounding crazier than the last, but tangible benefits never seem to appear.
Physicist Richard Feynman, one of the first to conceive of a quantum computer, due to his interest in the relationship between physics and computation, often has a quote attributed to him – it’s possibly apocryphal, but most certainly apt: “If you think you understand quantum mechanics, then you don’t.” The same is almost certainly true of quantum computing, where there are so many new terms and variables to consider, it seems impossible for a single human brain to hold them all. The fact that so many of them sound like science fiction is perhaps part of the discipline’s appeal.
Having multiple approaches to solving the same problem certainly keeps the scene lively, and we envisage endless debates between scientists along the lines of whether Intel or AMD is best, and whether the cryogenic cooling plant really needs all that RGB. It also means that we’ve had a solid run of news announcements and tech demonstrations recently, as work held up by the pandemic begins to bear fruit.
Bending thermodynamics probably...
Take time crystals. Yes, really. Despite sounding like something the Emperor Zog is searching for, protected by a plucky band of heroes including at least four kids and a puppet, a time crystal is a real thing: Google has made them using a quantum computer.
Emperor Zog can relax, however. A time crystal has possible practical uses as quantum memory or as a sensitive detector of quantum fields but isn’t going to destroy the universe. Imagine a system of particles in its lowest energy state, meaning it cannot lose any more energy to its environment, yet remaining in motion. The particles cannot come to rest because they are already in their quantum ground state, and usually would be still, but remain moving. It sounds like perpetual motion does an end-run around the second law of thermodynamics, but it has been demonstrated by a team from Stanford, MIT, and Google using Google’s Sycamore quantum processor.
Being in motion means it can flip between two states without losing energy, in theory doing this forever like a pendulum that will never stop swinging. MIT physicist Frank Wilczek wasn’t involved in the work, but he hypothesised the existence of time crystals back in 2012. “They can be sensitive probes of certain kinds of external fields, so they will give us, in principle,.
