Long live the qubit! The world record for how long the quantum computing equivalent of a bit can be trapped within a sliver of silicon has been smashed.
The previous record for one of these delicate quantum states lasting inside a material was a few seconds, making qubits tricky to work with. Now a team has coaxed them into existing for over 3 minutes. The feat could be a huge step towards silicon-based quantum computers, which would be many orders of magnitude faster than classical ones.
Mike Thewalt of Simon Fraser University, Burnaby, Canada, and colleagues used a sample of ultra-pure silicon-28 that contained some phosphorus atoms. Silicon-28 is not magnetic so the atoms had almost no effect on the magnetic moment, or nuclear spin, of the phosphorus, meaning that these atoms behaved as though they were in a vacuum.
The team aligned the spins of the phosphorus atoms and deduced the radio-frequency pulse that could flip the spins by 180 degrees. They then applied half this pulse, causing the spins to enter a superposition of two states: flipped and not flipped – the definition of a qubit.
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They were able to maintain the superposition for 192 seconds by applying a series of pulses that prevented the qubits from interacting with the silicon. Though similar times have been achieved in qubits made of atoms in a vacuum, this is a record for qubits in a material. “Not only is it a real material, it’s the same material that current computers are made of,” says team member John Morton of the University of Oxford.
Journal reference: Science, DOI: 10.1126/science.1217635
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