Experimental setup for the combined study of spin ensembles and superconducting quantum circuits

TL;DR

This paper presents an innovative cryogenic setup that enables the integration of superconducting qubits and spin ensembles within a single dilution refrigerator, overcoming magnetic crosstalk and thermal challenges for hybrid quantum computing.

Contribution

The authors develop and demonstrate the first experimental setup that decouples magnetic fields and maintains qubit stability in hybrid quantum systems.

Findings

Magnetic crosstalk is suppressed by over eight orders of magnitude.

The setup allows spin control fields up to 50 mT without destabilizing superconducting qubits.

Minimal thermal load is added by the solenoid operation.

Abstract

A hybrid quantum computing architecture combining quantum processors and quantum memory units allows for exploiting each component's unique properties to enhance the overall performance of the total system. However, superconducting qubits are highly sensitive to magnetic fields, while spin ensembles require finite fields for control, creating a major integration challenge. In this work, we demonstrate the first experimental setup that satisfies these constraints and provides verified qubit stability. Our cryogenic setup comprises two spatially and magnetically decoupled sample volumes inside a single dilution refrigerator: one hosting flux-tunable superconducting qubits and the other a spin ensemble equipped with a superconducting solenoid generating fields up to 50 mT. We show that several layers of Cryophy shielding and an additional superconducting aluminum shield suppress magnetic crosstalk by more than eight orders of magnitude, ensuring stability of the qubit's performance. Moreover, the operation of the solenoid adds minimal thermal load on the relevant stages of the dilution refrigerator. Our results enable scalable hybrid quantum architectures with low-loss integration, marking a key step toward scalable hybrid quantum computing platforms.