Russian team runs three-qubit CCZ gate in one 65 ns pulse with 99.39% fidelity on fluxonium processor

Russian researchers have built a three-qubit quantum processor that performs operations with 99.39% fidelity, ixbt.com reports. The result is described as a world record for gates of this type ixbt.comixbt.comixbt.comOpen source ↗. The complex three-qubit CCZ operation is executed by a single microwave pulse lasting 65 nanoseconds rather than a sequence of several transformations.

CCZ is usually implemented with eight two-qubit operations. Each extra step raises the probability of error, so reducing their number improves the accuracy of quantum computation. According to the developers, a conventional implementation would need two-qubit gates with about 99.94% fidelity each to reach comparable accuracy. Reaching that level on superconducting devices is still difficult.

The processor module was created by researchers at MISIS University, the Russian Quantum Center, INME RAS and MIPT. It consists of three superconducting fluxonium qubits coupled through a shared transmon element. The operation is controlled by a single pulse whose parameters are tuned with standard calibration methods.

The scientists consider the architecture suitable for building larger quantum processors. They plan to adapt it to two-dimensional layouts while keeping the mechanisms that suppress unwanted interactions between qubits ixbt.comixbt.comixbt.comOpen source ↗.