Shanghai team demonstrates a fast all-microwave two-qubit gate

[Dan_38]

Another team has found a new way to make fast two qubit gates. Quantum Zeitgeist reports that researchers at the Shanghai Institute of Microsystem and Information Technology, led by Wan-Peng Gao, built a controlled Z gate driven only by microwaves

The method uses Autler-Townes energy level engineering, which shifts the qubits' energy levels with microwave drives rather than tuning them with magnetic flux. It was tested on two Xmon qubits at 5.272 and 5.124 gigahertz

The gate takes 97 nanoseconds and reaches 99.40 percent fidelity. About 78 percent of the errors come from decoherence, and the authors say the approach also needs fewer two qubit gates to build a Toffoli gate

The work is a preprint on arXiv and has not yet been peer reviewed. Some coherence values are missing from the article

All microwave control is attractive because it can avoid flux noise and simplify wiring. Fidelity of 99.4 percent is below the very best gates, but with most errors coming from decoherence, better qubits should lift it. Fewer gates for common operations would also save valuable time on noisy hardware

Are microwave only gates the way forward? And how quickly is Chinese quantum hardware catching up?

A 97-nanosecond Gate Could Help Scale Up Superconducting Qubitsquantumzeitgeist.com