Microwave Quantum Link between Superconducting Circuits Housed in Spatially Separated Cryogenic Systems.

Area of Science:

• Quantum computing
• Quantum optics
• Quantum communication networks

Background:

• Superconducting circuits are key for quantum computing but face challenges with cryogenic temperatures and coherence-preserving microwave-to-optical conversion.
• Current limitations hinder the development of quantum networks spanning different cryogenic systems or long distances.

Purpose of the Study:

• To demonstrate a method for coherent linking of superconducting qubits over a distance.
• To enable on-demand state transfer and entanglement generation between spatially separated superconducting qubits.

Main Methods:

• Utilized a cryogenic waveguide to connect transmon qubits in two dilution refrigerators separated by five meters.
• Performed on-demand qubit state transfer and entanglement generation experiments.

Main Results:

• Achieved successful coherent linking of transmon qubits across a five-meter distance.
• Demonstrated on-demand qubit state transfer with an average fidelity of 85.8%.
• Generated entanglement on demand with a target state fidelity of 79.5%.

Conclusions:

• Cryogenic microwave links are a viable solution for connecting superconducting quantum systems.
• This technology facilitates the scaling of quantum computing systems and the creation of local area superconducting quantum communication networks.