A dispersive nanoSQUID magnetometer for ultra-low noise, high bandwidth flux detection

Abstract

We describe a dispersive nanoSQUID magnetometer comprised of two variable thickness aluminum weak-link Josephson junctions shunted in parallel with an on-chip capacitor. This arrangement forms a nonlinear oscillator with a tunable 4-8 GHz resonant frequency with a quality factor Q = 30 when coupled directly to a 50 $\Omega$ transmission line. In the presence of a near-resonant microwave carrier signal, a low frequency flux input generates sidebands that are readily detected using microwave reflectometry. If the carrier excitation is sufficiently strong then the magnetometer also exhibits parametric gain, resulting in a minimum effective flux noise of 30 n${\Phi }_0$/Hz${}^{1/2}$ with 20 MHz of instantaneous bandwidth. If the magnetometer is followed with a near quantum-noise-limited Josephson parametric amplifier, we can increase the bandwidth to 60 MHz without compromising sensitivity. This combination of high sensitivity and wide bandwidth with no on-chip dissipation makes this device ideal for local sensing of spin dynamics, both classical and quantum.

5 pages, 4 figures

References in corpus (3)

• Quantum feedback control of a superconducting qubit: Persistent Rabi oscillations
• Observation of quantum jumps in a superconducting artificial atom
• Nonlinear microwave response of aluminum weak-link Josephson oscillators

Cited by in corpus (6)

• Resonantly phase-matched Josephson junction traveling wave parametric amplifier
• Switching times in long-overlap Josephson junctions subject to thermal fluctuations and non-Gaussian noise sources
• A three-junction SQUID-on-tip with tunable in-plane and out-of-plane magnetic field sensitivity
• Quantum metrology of low frequency electromagnetic modes with frequency upconverters
• Ultra-Highly Linear Magnetic Flux-to-Voltage response in Proximity-based Mesoscopic bi-SQUIDs
• Ultra linear magnetic flux-to-voltage conversion in superconducting quantum interference proximity transistors