Single-Spin Magnetomechanics with Levitated Micromagnets.

We demonstrate a new mechanical transduction platform for individual spin qubits. In our approach, single micromagnets are trapped using a type-II superconductor in proximity of spin qubits, enabling direct magnetic coupling between the two systems. Controlling the distance between the magnet and the superconductor during cooldown, we demonstrate three-dimensional trapping with quality factors around 1×10^{6} and kHz trapping frequencies. We further exploit the large magnetic moment to mass ratio of this mechanical oscillator to couple its motion to the spin degrees of freedom of an individual nitrogen vacancy center in diamond. Our approach provides a new path towards interfacing individual spin qubits with mechanical motion for testing quantum mechanics with mesoscopic objects, realization of quantum networks, and ultrasensitive metrology.

Optically levitated nanoparticle as a model system for stochastic bistable dynamics.

Nano-mechanical resonators have gained an increasing importance in nanotechnology owing to their contributions to both fundamental and applied science. Yet, their small dimensions and mass raises some challenges as their dynamics gets dominated by nonlinearities that degrade their performance, for instance in sensing applications. Here, we report on the precise control of the nonlinear and stochastic bistable dynamics of a levitated nanoparticle in high vacuum. We demonstrate how it can lead to efficient signal amplification schemes, including stochastic resonance. This work contributes to showing the use of levitated nanoparticles as a model system for stochastic bistable dynamics, with applications to a wide variety of fields.

Second-harmonic generation from split-ring resonators on a GaAs substrate.

We study second-harmonic generation from gold split-ring resonators on a crystalline GaAs substrate. By systematically varying the relative orientation of the split-ring resonators with respect to the incident linear polarization of light and the GaAs crystallographic axes, we unambiguously identify a nonlinear contribution that originates specifically from the interplay of the local fields of the split-ring resonators and the bulk GaAs second-order nonlinear-susceptibility tensor. The experimental results are in good agreement with theoretical modeling.