Spatially resolved surface dissipation over metal and dielectric substrates

We report spatially resolved measurements of static and fluctuating electric fields over conductive (Au) and non-conductive (SiO2) surfaces. Using an ultrasensitive `nanoladder' cantilever probe to scan over these surfaces at distances of a few tens of nanometers, we record changes in the probe resonance frequency and damping that we associate with static and fluctuating fields, respectively. We find that the two quantities are spatially correlated and of similar magnitude for the two materials. We quantitatively describe the observed effects on the basis of trapped surface charges and dielectric fluctuations in an adsorbate layer. Our results provide direct, spatial evidence for surface dissipation in adsorbates that affects nanomechanical sensors, trapped ions, superconducting resonators, and color centers in diamond

Force-detected Magnetic Resonance Imaging of Influenza Viruses in the Overcoupled Sensor Regime

Long and thin scanning force cantilevers are sensitive to small forces, but also vulnerable to detrimental non-contact interactions. Here we present an experiment with a cantilever whose spring constant and static deflection are dominated by the interaction between the tip and the surface, a regime that we refer to as ``overcoupled''. The interactions are an obstacle for ultrasensitive measurements like nanoscale magnetic resonance imaging (nanoMRI). We discuss several strategies to overcome the challenges presented by the overcoupling, and demonstrate proton nanoMRI measurements of individual influenza virus particles.Comment: 9 pages, 9 figure

Extracting the lifetime of a synthetic two-level system

The Kerr Parametric Oscillator (KPO) is a nonlinear resonator system that is often described as a synthetic two-level system. In the presence of noise, the system switches between two states via a fluctuating trajectory in phase space, instead of following a straight path. The presence of such fluctuating trajectories makes it hard to establish a precise count or even a useful definition, of the “lifetime” of the state. Addressing this issue, we compare several rate counting methods that allow to estimate a lifetime for the levels. In particular, we establish that a peak in the Allan variance of fluctuations can also be used to determine the levels’ lifetime. Our work provides a basis for characterizing KPO net- works for simulated annealing where an accurate determination of the state lifetime is of fundamental importance.ISSN:0003-6951ISSN:1077-311