When researchers at Google announced last fall that they had achieved “quantum superiority”—a point at which a quantum computer can perform a task beyond the reach of regular computers—some people wondered what the big deal was. The program, which checked the output of a random number generator, was of limited practical value and did not prove that the company’s machine could do anything useful, critics said.
Now, however, Google’s quantum computer has achieved something that could have real-world applications: successfully simulating a simple chemical reaction. The feat points the way toward quantum chemistry, which could expand scientists’ understanding of molecular reactions and lead to useful discoveries, such as better batteries, new ways to make fertilizer and improved methods of removing carbon dioxide from the air.
Last year’s quantum superiority experiment was run on a chip dubbed Sycamore, which contained 53 superconducting quantum bits, or qubits. Chilled to near absolute zero, the qubits take on quantum-mechanical properties, allowing scientists to manipulate them in more complicated and useful ways than the simple “on/off” flows of current that make up the bits of classical computers. The hope is that one day, quantum computers will become powerful enough to quickly perform calculations that would take the lifetime of the universe for a classical computer to complete.
This quantum-chemistry experiment, which was described in the August 28 issue of the journal Science, relied on the same basic Sycamore design, though it only used 12 qubits. But it demonstrates the