Scientists create the quietest semiconductor quantum bits

Researchers at UNSW in Sydney have demonstrated the lowest noise level in history for a semiconductor quantum bit or qubit. Research published in Advanced Materials.

For quantum computers to perform useful computations, quantum information must be close to 100% accurate. Charging noise caused by the imperfection of the material environment in which the qubits are located interferes with the quantum information encoded on them, affecting the accuracy of the information. Scientists have figured out how to solve the problem by optimizing the manufacturing process of a silicon chip

“The level of charge noise in semiconductor qubits has been a major obstacle to achieving the levels of accuracy we need for large-scale quantum computers,” explains lead author Ludwik Krantz, Ph.D. and student at UNSW’s Center for Quantum Computing and Communication Technologies.

“Our research has shown that we can reduce charge noise to a much lower level while minimizing its effect on our qubits,” said Krantz. “By optimizing the silicon chip manufacturing process, we achieved a noise level 10 times lower than previously recorded. This is the lowest recorded charge noise of any semiconductor qubit. ”

Qubits made from electrons placed on atomic qubits in silicon are a promising platform for large-scale quantum computers. However, qubits placed on any semiconductor platform such as silicon are sensitive to charge noise. The team’s research showed that the presence of defects inside the silicon chip or at the interface with the surface makes a significant contribution to the charge noise. By reducing the number of impurities in the silicon chip and placing atoms away from surfaces and interfaces where most of the noise occurs, the team was able to achieve a record result.