Superconducting qubit magnetometer: optimization of phase estimation algorithms and advances in quantum devices

We present optimized phase estimation algorithms (PEAs) applied to superconducting qubits for quantum-enhanced magnetometry [1], outperforming existing methods in both sensitivity and efficiency. By applying these optimized PEAs to superconducting qubits, we identify optimal points for enhanced precision in practical applications. We evaluate the absolute sensitivity of existing N-qubit platforms, where N qubits are pulse-operated in parallel, both entangled and unentangled. Additionally, we present the implementation of a DC magnetometer based on a fluxonium superconducting qubit [2], significantly improving measurement accuracy with the use of an auxiliary antenna. For AC signal sensitivity, we propose the Constant-Time Dynamical Decoupling method [3], reducing the total time-to-solution by up to 50% and enhancing the detection and analysis of AC signals. Furthermore, we report on NbTiN thin films deposited on MgO, as well as devices containing resonators and SQUIDs [4], which demonstrate robust performance at elevated temperatures. These advancements lay the groundwork for quantum-enhanced sensors capable of outperforming the best existing sensors.