Massachusetts Institute of Technology (MIT) researchers have developed a new approach to maintaining quantum superposition using synthetic diamonds.
The team's research describes a feedback-control system that requires no measurement of the current state of quantum bits (qubits), which destroys superposition. The system uses a nitrogen-vacancy (NV) center in a diamond and implements feedback with a quantum controller. "Because the controller is quantum, I don't need to do a measurement to know what's going on," explains MIT professor Paola Cappellaro.
When subjected to a strong magnetic field, an NV center's electronic spin can be up, down, or a quantum superposition of the two. A dose of microwaves initially puts the NV center's electronic spin into superposition, and then a burst of radio-frequency radiation puts the nitrogen nucleus into a specified spin state. A second, lower-power dose of microwaves entangles the spins of the nitrogen nucleus and the NV center, so they become dependent on each other. At that point, the NV qubit could be put to work along with other qubits to perform a computation, but the researchers also used further microwave exposures to test for errors.
They report the system enabled an NV-center quantum bit to stay in superposition about 1,000 times as long as it would otherwise which, they say, could make possible reliable, working quantum computers.
From IDG News Service
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