A new method of making the fundamental building blocks of quantum computers has brought them closer to actual use. IBM announced today that it has created quantum bits (qubits) that can retain their properties for 100 microseconds at a time — twice to four times the previously reported record. This new record, along with breakthroughs in reducing errors, brings performance near the minimum required to create a practical quantum computer.
IBM's qubits are built on a design pioneered by Yale in which a single qubit is suspended in a cavity set within a brick of metal. Although each cavity is relatively large (about an inch and a half in its current state), IBM says it could potentially scale the process to create a system with hundreds of thousands of qubits. Once assembled, these qubits are then placed inside a refrigerated chamber to reduce interference.
Unlike ordinary computers, which can hold a value of either "1" or "0," qubits can also hold both values simultaneously using a property called "superposition" — think the computing version of the Schrödinger's Cat thought experiment. Because of this, quantum computers are able to work on massive numbers of calculations at once, and could revolutionize fields like data encryption that rely on factoring large numbers. However, since heat, electromagnetic radiation, or materials defects can all cause errors in basic functions and are extremely difficult to eliminate, only very basic proofs of concept have been successfully created. Likewise, qubits retain their quantum properties for only fractions of a second each, so a functioning computer would need to be built on a massive scale. IBM will be presenting its results at the American Physical Society meeting this week in Boston.