Ťhe technology behind everyday computers such as smartphones and laptops has revolutionised modern life, to the extent that our our day-to-day lives are unimaginable without it. But an alternative method of computing is advancing rapidly, and Boris Johnson is among the people who have noticed. He will need to push the boundaries of his linguistic dexterity to explain it.
Quantum computing is based on quantum physics, which looks at how the subatomic particles that make up the universe work. 上个星期, 这 prime minister promised the UK would “go big on quantum computing” by building a general-purpose quantum computer, and secure 50% of the global quantum computing market by 2040. The UK will need to get a move on though: big steps have been taken in the field this year by the technology superpowers of China and the US.
Peter Leek, a lecturer and quantum computing expert at Oxford University, says “classical” computing (the common term for computing as we know it) has been an incredible 20th-century achievement, 但: “the way we process information in computers now still doesn’t take full advantage of the laws of physics as we know them”.
Work on quantum physics, 然而, has given us a new and more powerful way of processing information. “If you can use the principles of quantum physics to process information then you can do a range of types of calculations that you cannot do with normal computers,” says Leek.
Classical computers encode their information in bits – represented as a 0 or a 1 – that are transmitted as an electrical pulse. A text message, email or even a Netflix film streamed on your phone is a string of these bits. In quantum computers, 然而, the information is contained in a quantum bit, or qubit. These qubits – encased in a modestly sized chip – are particles such as electrons or photons that can be in several states at the same time, a property of quantum physics known as superposition. This means qubits can encode various combinations of 1s and 0s at the same time – and compute their way through vast numbers of different outcomes.
“If you compared a piece of memory in a normal computer, it is in a unique state of ones and zeroes, ordered in a specific way. In a quantum computer that memory can be simultaneously in all possible states of ones and zeroes,” says Leek.
To really harness this power requires an “entanglement” of pairs of qubits: if you double the number of qubits the computing power increases exponentially. Link these entangled qubit pairs together and you get a very powerful computer that can crunch through numbers at unprecedented speed, provided there is a quantum algorithm (the set of instructions followed by the computer) for the calculation you want to do.
Jay Gambetta, a VP of quantum computing at IBM, which last week unveiled the world’s most powerful quantum processor, 说: “The combined system has a computational power that is much more than the individual systems.” The computer firm’s US-made Eagle quantum processor – a type of computer chip – strings together 127 qubits compared with the 66 achieved recently by the University of Science and Technology of China (USTC) in Hefei.
Gambetta stresses that the practical applications of quantum computers are not there yet, but theoretically they could have exciting uses like helping design new chemicals, drugs and alloys. Quantum computing could result in a much more efficient representation of chemical compounds, says Gambetta, predicting accurately what a complex molecule might do and paving the way for new drugs and materials. “It gives us a way to model nature better,” he adds.
There are ways in which quantum computing could help combat global heating, 也, says Gambetta, by more efficiently separating carbon dioxide into oxygen and carbon monoxide, reducing the amount of CO2 in the atmosphere. Alternatively, quantum computing could help understand how we can make fertiliser by using much less energy.
去年, IBM teamed up with German carmaker Daimler, the parent of Mercedes-Benz, to use quantum computing to model new lithium batteries. Renewable energy, pharmaceuticals, electric cars, fertiliser: if these are just some of the products that can be enhanced by quantum computing, then the UK understandably wants to be at the forefront of the market.
Once quantum computing reaches the 1,000 qubit level it should be able to achieve what IBM calls “quantum advantage”, where a quantum computer consistently solves problems faster than a classical computer. IBM is hoping to reach 1,000 qubits via its Condor processor in 2023.
The UK’s strong university system – and long history of innovation, epitomised by Alan Turing in computing and Paul Dirac in quantum mechanics – gives the country some hope of achieving Johnson’s goal. But Gambetta’s IBM colleague Bob Sutor says that for the UK and other countries ambitious in making advances in quantum computing, educations and skills are key – at university level and below, including schools. “The more people working on it, the faster we will get there.”