1. What’s the appeal of quantum computers?
They can do things that classical computers can’t. Google revealed in April that one of its quantum computers had solved a problem in seconds that would have taken the world’s most powerful supercomputer 47 years. Experimental quantum computers are typically given tasks that a conventional computer would take too long to do, such as simulating the interaction of complex molecules for drug discovery. Their greatest potential is for modeling complex systems involving large numbers of moving parts whose behavior changes as they interact — such as predicting the behavior of financial markets, optimizing supply chains and operating the large language models used in generative artificial intelligence. They’re not expected to be much use in the laborious but simpler work fulfilled by most of today’s computers — processing a more limited number of isolated inputs sequentially on a mass scale.
2. Who’s building them?
Canadian company D-Wave Systems Inc. became the first to sell quantum computers to solve optimization problems in 2011. International Business Machines Corp., Alphabet Inc.’s Google, Amazon Web Services and numerous startups have all created working quantum computers. More recently, companies such as Microsoft Corp. have made progress toward building scalable and practical quantum supercomputers. Intel Corp. started shipping a silicon quantum chip to researchers with transistors known as qubits (quantum bits) that are as much as 1 million times smaller than other types. Microsoft and other companies, including startup Universal Quantum, expect to build a quantum supercomputer within the next ten years. China is building a $10 billion National Laboratory for Quantum Information Sciences as part of a big push in the field.
3. How do quantum computers work?
They use tiny circuits to perform calculations, as do traditional computers. But they make these calculations in parallel, rather than sequentially, which is what makes them so fast. Regular computers process information in units called bits, which can represent one of two possible states — 0 or 1 — that correspond to whether a portion of the computer chip called a logic gate is open or closed. Before a
traditional computer moves on to process the next piece of information, it must have assigned the previous piece a value. By contrast, thanks to the probabilistic aspect of quantum mechanics, the qubits in quantum computers don’t have to be assigned a value until the computer has finished the whole calculation. This is known as “superposition.” So whereas three bits in a conventional computer would only be able to represent one of eight possibilities – 000, 001, 010, 011, 100, 101, 110 and 111 – a quantum computer of three qubits can process all of them at the same time. A quantum computer with 4 qubits can in theory handle 16 times as much information as an equally-sized conventional computer and will keep doubling in power with every qubit that’s added. That’s why a quantum computer can process exponentially more information than a classic computer.