All-Microwave Manipulation of Superconducting Qubits with a Fixed-Frequency Transmon Coupler

Area of Science:

• Quantum Computing
• Superconducting Circuits
• Quantum Control

Background:

• All-microwave control of fixed-frequency superconducting quantum computing circuits offers benefits in reducing noise and wiring complexity.
• Superconducting transmons are key elements in building quantum processors.

Purpose of the Study:

• To introduce and model a novel swap interaction between two data transmons using a coupler transmon's nonlinearity.
• To implement an all-microwave controlled-Z gate based on this coupler-assisted swap interaction.

Main Methods:

• Analytical and numerical modeling of the coupler-assisted swap interaction.
• Utilizing the third-order nonlinearity of a coupler transmon under microwave drive.
• Implementing a controlled-Z gate using the developed swap interaction.

Main Results:

• The coupler-assisted swap transition was successfully modeled and implemented.
• The all-microwave controlled-Z gate demonstrated high drive efficiency.
• The gate exhibited small residual interaction across a broad detuning range between data transmons.

Conclusions:

• All-microwave control via coupler-assisted swap interactions is a viable strategy for superconducting quantum computing.
• This approach effectively minimizes noise channels and wiring costs.
• The developed gate is robust to detuning, enhancing practical quantum circuit implementation.