Sensitive spin detection using an on-chip SQUID-waveguide resonator

TL;DR

This paper introduces a new on-chip SQUID-waveguide resonator setup for sensitive spin resonance detection, enabling better control of multi-level spin systems in quantum computing applications.

Contribution

The paper presents a novel integrated device combining a dc-SQUID and coplanar waveguide for enhanced spin resonance measurement under high magnetic fields.

Findings

Detected Gd spin resonance signals between excited states

Demonstrated operation with high magnetic field parallel to chip

Achieved sensitive detection suitable for quantum computing

Abstract

Precise detection of spin resonance is of paramount importance to achieve coherent spin control in quantum computing. We present a novel setup for spin resonance measurements, which uses a dc-SQUID flux detector coupled to an antenna from a coplanar waveguide. The SQUID and the waveguide are fabricated from 20~nm Nb thin film, allowing high magnetic field operation with the field applied parallel to the chip. We observe a resonance signal between the first and third excited states of Gd spins $S=7/2$ in a CaWO$_4$ crystal, relevant for state control in multi-level systems.