Quantum computers can be made using arrays of atoms
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A device with more than 6000 quantum bits, or qubits, has smashed a previously-held record and is the first step towards building the largest quantum computer yet.
There is currently no single, consensus design for building a quantum computer, but researchers believe that for these devices to be useful, they will have to comprise at least tens of thousands of qubits. The current record holder is a machine from Atom Computing, with 1180 qubits, but Hannah Manetsch at the California Institute of Technology and her colleagues have now built a device with 6100 qubits.
Each of these is a neutral caesium atom cooled to temperatures close to absolute zero and controlled by laser beams, with all 6100 of them arranged in a neat grid. The researchers designed the qubits to have properties exceptionally suitable for use in computations, says Manetsch, although they haven’t yet performed any.
For instance, they tuned the lasers’ frequency and power to ensure that the naturally fragile qubits maintain their quantum states and that the whole grid remains stable for as long as possible, which will enable more accurate computations and longer runtimes for an eventual quantum computer. The team has also tested how well the lasers can move qubits between different parts of the array, which will be an important part of running computations, says team member Elie Bataille, also at the California Institute of Technology.
“This is an amazing demonstration of the simple scaling that neutral atoms have to offer,” says Ben Bloom at Atom Computing, which also uses neutral atoms in its device.
Mark Saffman at the University of Wisconsin-Madison says that the new experiment is encouraging as proof that neutral atom quantum computers can be made very large, but more experimental tests need to be done before the team’s setup could be considered a full-fledged quantum computer.
The researchers are now starting to explore the best ways to get their qubits to run computations, and do so in an error-proof way, says team member Kon Leung, also at the California Institute of Technology. Ultimately, they believe that they can scale their machine to a million qubits within about a decade, he says.
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