Toshiba researchers have made a breakthrough in quantum computer architecture: the basic design of a two-channel sensing coupler that will improve the speed and accuracy of quantum computing with a tunable coupler. The coupler is a key device that determines the performance of superconducting quantum computers. The tunable coupler in a superconducting quantum computer is responsible for connecting two quantum bits and performing quantum computations by turning the coupling between them on and off.
The current technique can turn off the coupling of superconducting quantum bits with close frequencies, but this is prone to crosstalk and the formation of errors when one of the quantum bits is irradiated by electromagnetic waves for control. In addition, current technology cannot completely turn off the coupling of quantum bits with significantly different frequencies, which in turn leads to errors due to residual coupling.
Toshiba has recently designed a dual-sensing coupler that can completely turn on and off the coupling between quantum bits with significantly different frequencies. Turning it fully on enables high-speed quantum computation with strong coupling while turning it fully off eliminates residual coupling, thereby improving the speed and accuracy of quantum computation.
Simulations performed with the new technology show that Toshiba has achieved double quantum gates, the fundamental operation in quantum computing, with 99.99% accuracy and a processing time of only 24 nanoseconds.
Toshiba’s dual quantum coupler can be applied to fixed-frequency quantum bits, achieving high stability and ease of design, and enabling the first coupling between fixed-frequency cross-gate bits with significantly different frequencies that can be fully turned on and off, and providing a high-speed, accurate dual-bit gate.
This technology is expected to drive the realization of higher-performance quantum computers that can contribute to areas such as achieving carbon neutrality and developing new drugs.