22 research outputs found
Magnetic field resilient superconducting fractal resonators for coupling to free spins
We demonstrate a planar superconducting microwave resonator intended for use in applications requiring strong magnetic fields and high quality factors. In perpendicular magnetic fields of 20 mT, the niobium resonators maintain a quality factor above 25 000 over a wide range of applied powers, down to single photon population. In parallel field, the same quality factor is observed above 160 mT, the field required for coupling to free spins at a typical operating frequency of 5 GHz. We attribute the increased performance to the current branching in the fractal design. We demonstrate that our device can be used for spectroscopy by measuring the dissipation from a pico-mole of molecular spins
Sensitivity Optimization for NV-Diamond Magnetometry
Solid-state spin systems including nitrogen-vacancy (NV) centers in diamond
constitute an increasingly favored quantum sensing platform. However, present
NV ensemble devices exhibit sensitivities orders of magnitude away from
theoretical limits. The sensitivity shortfall both handicaps existing
implementations and curtails the envisioned application space. This review
analyzes present and proposed approaches to enhance the sensitivity of
broadband ensemble-NV-diamond magnetometers. Improvements to the spin dephasing
time, the readout fidelity, and the host diamond material properties are
identified as the most promising avenues and are investigated extensively. Our
analysis of sensitivity optimization establishes a foundation to stimulate
development of new techniques for enhancing solid-state sensor performance.Comment: 73 pages, 36 figures, 17 table
Ultralong Dephasing Times in Solid-State Spin Ensembles via Quantum Control
Quantum spin dephasing is caused by inhomogeneous coupling to the
environment, with resulting limits to the measurement time and precision of
spin-based sensors. The effects of spin dephasing can be especially pernicious
for dense ensembles of electronic spins in the solid-state, such as for
nitrogen-vacancy (NV) color centers in diamond. We report the use of two
complementary techniques, spin bath control and double quantum coherence, to
enhance the inhomogeneous spin dephasing time () for NV ensembles by
more than an order of magnitude. In combination, these quantum control
techniques (i) eliminate the effects of the dominant NV spin ensemble dephasing
mechanisms, including crystal strain gradients and dipolar interactions with
paramagnetic bath spins, and (ii) increase the effective NV gyromagnetic ratio
by a factor of two. Applied independently, spin bath control and double quantum
coherence elucidate the sources of spin dephasing over a wide range of NV and
spin bath concentrations. These results demonstrate the longest reported
in a solid-state electronic spin ensemble at room temperature, and
outline a path towards NV-diamond magnetometers with broadband femtotesla
sensitivity.Comment: PRX versio
Edge-Based Compartmental Modeling for Infectious Disease Spread Part III: Disease and Population Structure
We consider the edge-based compartmental models for infectious disease spread
introduced in Part I. These models allow us to consider standard SIR diseases
spreading in random populations. In this paper we show how to handle deviations
of the disease or population from the simplistic assumptions of Part I. We
allow the population to have structure due to effects such as demographic
detail or multiple types of risk behavior the disease to have more complicated
natural history. We introduce these modifications in the static network
context, though it is straightforward to incorporate them into dynamic
networks. We also consider serosorting, which requires using the dynamic
network models. The basic methods we use to derive these generalizations are
widely applicable, and so it is straightforward to introduce many other
generalizations not considered here
Abstracts from the 8th International Conference on cGMP Generators, Effectors and Therapeutic Implications
This work was supported by a restricted research grant of Bayer AG