Quantum computers are computers that consist of quantum bits, or “qubits,” that play a similar role to the bits in today's digital computers. The laws of quantum mechanics allow qubits to encode exponentially more information than bits. By manipulating information stored in these qubits, scientists can quickly produce high-quality solutions to difficult problems. This means quantum computing may revolutionize our ability to solve problems that are hard to address with even the largest supercomputers. Scientists have demonstrated these quantum speedups in several applications, including database searches. The race is now on to find others.

Researchers expect quantum computers to be particularly good at calculating properties of physical systems that are inherently quantum mechanical. These applications include molecules used as chemical catalysts, which despite their large size are subject to quantum mechanics. They also include the quarks and gluons that clump together inside the nuclei of atoms. Quantum computers may also be especially good at solving optimization problems, which involve choosing the best alternative from a huge range of options. The quantum computers available today are small, noisy prototypes, but the field is progressing rapidly.