Quantum computers could run more quickly if they contained tiny quantum refrigerators.
Quantum computers process information using quantum bits, or qubits, which must be reset to a special state between running programs. Teruaki Yoshioka at the Tokyo University of Science says slow reset times can become a real computational bottleneck, especially if they are slower than the speed of operations of a quantum computer.
He and his colleagues have devised a way to make this resetting process shorter by using a nano-sized quantum circuit refrigerator (QCR).
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They built a qubit onto a chip and then added two more components: a small resonator and their QCR, which was built partly from superconducting aluminium and partly from copper.
When the qubit was in a state that was too energetic to perform a calculation, the team could transfer some of its energy to the resonator, which would convert it to a particle of light. That particle was then captured by an electron in the QCR, thus removing energy from the resonator and the qubit, effectively making the latter colder and ready for use. Similar past experiments had reset times close to 300 nanoseconds, but the QCR method shortened them by about 100 nanoseconds.
at Aalto University in Finland says quantum computers have to be kept in special refrigerators because they make more errors when warm. Adding tiny QCR-like fridges directly onto their chips could reduce some of the difficulties involved in making those large cooling devices.
However, researchers must still compare the new method more precisely to other qubit reset mechanisms, as well as test it with state-of-the-art qubits, says at Yale University.
Yoshioka鈥檚 team is already working on optimising their experiment to make qubit resetting even faster听鈥� and they want to test whether they can reset multiple qubits simultaneously, says at the National Institute of Advanced Industrial Science and Technology in Japan, who worked on the project. This is important since the best quantum computers today use dozens to hundreds of qubits 鈥� and not all of them are made the same way. 鈥淚 think we could also use the QCR to reset a different kind of qubit,鈥� says Nakamura.
Physical Review Applied
