Superconducting microwave oscillators as detectors for ESR spectroscopy

Abstract

Microwave superconducting resonators are extensively studied in fields such as quantum computing and electron spin resonance (ESR) spectroscopy. However, the integration of superconducting resonators with feedback mechanisms to create ultra-low noise oscillators is a relatively unexplored area, and the application of such oscillators in ESR spectroscopy has not yet been demonstrated. In this work, we report the design, fabrication, and application of microwave oscillators based on superconducting resonators for ESR spectroscopy, illustrating an alternative way for the improvement of the performance of oscillator based ESR sensors. Specifically, ESR spectra are obtained by measuring the oscillator's frequency shift induced by the ESR effect as a function of the applied static magnetic field. The oscillators are composed of a single heterojunction bipolar transistor (HBT) or high electron mobility transistor (HEMT) coupled with NbTi or YBa${}_2$Cu${}_3$O${}_7$ (YBCO) superconducting resonators. The fabricated oscillators operate at frequencies of 0.6 and 1.7 GHz and temperatures up to 80 K (for YBCO resonators) and 8 K (for NbTi resonators). The lowest measured frequency noise is about 9 mHz/Hz${}^{1/2}$ (-139 dBc/Hz), the best spin sensitivity is about $1\times 10^{10}$ spins/Hz${}^{1/2}$, and the best concentration sensitivity is about $3\times 10^{18}$ spins/Hz${}^{1/2}$m${}^3$. The approach proposed in this work should allow for significantly better spin and concentration sensitivities compared to those achievable with normal conductors, up to operating frequencies, magnetic fields, and temperatures where superconductors exhibit substantially lower effective microwave resistance than normal conductors.

article, 7 pages, 4 figures, supplementary material, 21 pages, 13 figures

References in corpus (16)

• Coplanar Waveguide Resonators for Circuit Quantum Electrodynamics
• High Kinetic Inductance Superconducting Nanowire Resonators for Circuit QED in a Magnetic Field
• Fabrication and characterization of superconducting circuit QED devices for quantum computation
• Reaching the quantum limit of sensitivity in electron spin resonance
• Magnetic field resilient superconducting coplanar waveguide resonators for hybrid cQED experiments
• Inductive-detection electron-spin resonance spectroscopy with $65$spins$/\sqrt{\text{Hz}}$ sensitivity
• Superconducting coplanar waveguide resonators for low temperature pulsed electron spin resonance spectroscopy
• Storing quantum information in spins and high-sensitivity ESR
• YBCO microwave resonators for strong collective coupling with spin ensembles
• Fast tunable high Q-factor superconducting microwave resonators
• Coherently coupling distinct spin ensembles through a high-$T_c$ superconducting resonator
• Microwave spectroscopy on heavy-fermion systems: probing the dynamics of charges and magnetic moments
• Magnetic Field Dependent Microwave Losses in Superconducting Niobium Microstrip Resonators
• Multi-frequency Spin Manipulation Using Rapidly Tunable Superconducting Coplanar Waveguide Microresonators
• Superconducting microresonators for electron spin resonance, the good, the bad, and the future
• Superconducting coplanar microwave resonators with operating frequencies up to 50 GHz

Cited by in corpus (1)

• Effects of the thin-film thickness on superconducting NbTi microwave resonators for on-chip cryogenic thermometry