Combining SQUID Devices and Microwave Resonators for Coherent Control and Detection of Quantum Spins

Large-scale, universal quantum computers are desired pieces of technology in both academic research and the private sector. One solution is to use spin systems such as Gd³⁺ and Mn²⁺ diluted within a non-magnetic host crystal, which can be integrated with superconducting circuits. Such spin systems possess high spin degrees of freedom (S=7/2 for Gd³⁺), leading to a rich energy level structure that can encode multi-qubit states. The transitions between energy levels are in the microwave range, and previous studies in our group have produced planar superconducting resonators [1,2] which are simple to fabricate and show promise for the purposes of quantum spin manipulation. We will discuss efforts made to design and optimize DC superconducting quantum interference devices (DC-SQUIDs) [3,4], integrated with a resonator into a single on-chip device to achieve coherent control and detection of quantum spin states.

[1] G. Franco-Rivera et al., Phys. Rev. Appl. 19, 024067 (2023).

[2] G. Franco-Rivera et al., Phys. Rev. Appl. 18, 014054 (2022).

[3] J. Cochran et al., IEEE Transactions on Applied Superconductivity 31, 1 (2021).

[4] G. Yue et al., Applied Physics Letters 111, 202601 (2017).