High-Fidelity, High-Scalability Two-Qubit Gate Scheme for Superconducting Qubits

Area of Science:

• Quantum Computing
• Superconducting Circuits
• Quantum Information Processing

Background:

• High-fidelity two-qubit gates are essential for scalable quantum information processing.
• Integrating quantum systems often leads to compromised gate fidelity.
• A low-error, scalable two-qubit gate scheme is highly needed.

Purpose of the Study:

• To experimentally demonstrate a novel two-qubit gate scheme.
• To achieve high-fidelity controlled-Z gates in superconducting quantum circuits.
• To provide a scalable solution for quantum information processing.

Main Methods:

• Utilized fixed-frequency qubits and a tunable coupler in a superconducting quantum circuit.
• Implemented a new two-qubit gate scheme.
• Employed interleaved randomized benchmarking for fidelity measurement.

Main Results:

• Demonstrated a controlled-Z gate in 30 nanoseconds with 99.5% fidelity.
• The scheme requires fewer control lines and reduces crosstalk.
• Error analysis indicated coherence limitations as the primary error source.

Conclusions:

• The new scheme simplifies calibration and is amenable to scaling.
• This work enables large-scale implementation of high-fidelity quantum operations.
• The demonstrated method addresses key challenges in integrated quantum systems.