On-Chip Detection of Electronuclear Transitions in the $^{155,157}$Gd Multilevel Spin System

TL;DR

This paper demonstrates on-chip detection of electronuclear transitions in Gd isotopes, enabling sensitive measurement of spin states and their coupling to superconducting resonators for quantum memory applications.

Contribution

It introduces a method for detecting forbidden electronuclear transitions in Gd isotopes using cavity perturbation, advancing quantum state control in rare-earth spin systems.

Findings

Detected approximately 7.6×10^7 spins via cavity perturbation.

Measured spin decoherence rates and spin-photon coupling strengths.

Enabled connection of quantum states with different spin projections.

Abstract

The properties of rare-earth elements diluted in non-magnetic crystals make them a promising candidate for a quantum memory due to their limited Hilbert space. The control and readout of the qubit states require a highly sensitive measurement and large coupling of the spin ensemble with the electro-magnetic mode of a superconducting resonator. We report sensitive detection of forbidden transitions of electronuclear states from the minority species of $^{155}$Gd and $^{157}$Gd isotopes which opens the possibility of connecting quantum states with very different spin projections. Cavity perturbation measurements seen in the reflected signal allows the detection of about 7.6$\times10^{7}$ spins and the measurement of spin decoherence rate and spin-photon coupling strength.