The quantum states of atoms and subatomic particles that prototype quantum computers use to represent the 1s and 0s of computer information are so fragile that the energy from heat, light and magnetism ordinarily found in their environments is usually enough to change them, effectively stuffing out the information they hold.
Rather than fight the odds, many researchers are working with the environmental noise to create safe havens for quantum bits, or qubits. Particles like atoms, electrons and photons can be used as qubits because they can be oriented in one of two directions — spin up and spin down. Qubits can also be encoded in the interactions of pairs of particles. The key to making protected qubits is to encode logical qubits in multiple physical qubits.
These approaches are central to efforts aimed at making viable quantum computers, said Jason Ollerenshaw, a researcher at the University of Toronto in Canada. “Techniques for resisting environmental noise will be essential in building quantum computers on a practical scale,” he said. Quantum computers hold the promise of solving certain types of problems like cracking secret codes that are far beyond the reach of ordinary computers.