Elastic strain engineering for ultralow mechanical dissipation

Abstract

Extreme stresses can be produced in nanoscale structures; this feature has been used to realize enhanced materials properties, such as the high mobility of silicon in modern transistors. We show how nanoscale stress can be used to realize exceptionally low mechanical dissipation when combined with "soft-clamping"-a form of phononic engineering. Specifically, using a nonuniform phononic crystal pattern, we colocalize the strain and flexural motion of a free-standing silicon nitride nanobeam. Ringdown measurements at room temperature reveal string-like vibrational modes with quality () factors as high as 800 million and × frequency exceeding 10 hertz. These results illustrate a promising route for engineering ultracoherent nanomechanical devices.

Spin detection with a micromechanical trampoline: towards magnetic resonance microscopy harnessing cavity optomechanics

“…In this article, we demonstrated that when depositing a micron-size grain on a trampoline tether, a Q>10 6 could be maintained, along with x zp of 5-7 fm. To utilize even higher Q devices of 10 8 or higher [5,6], a sample (either a magnetic grain or a spin sample, as in figure 1) with smaller dimensions should be deposited. We expect that deposition of magnetic sample with dimensions of less than a micron will require a more integrated deposition method.…”

“…Experimenters have harnessed unique mechanical resonators with both high resonant frequencies, which favor the observation of quantum effects in comparison to thermal scales, and high quality factors that offer environmental isolation. In particular tensioned elements, for example silicon nitride (Si 3 N 4 ) strings or drums, were found to be well-adapted to cavity optomechanics [2], and ultracoherent mechanical tensioned resonators have been enabled by engineering phononic bandgaps and bending profiles [3][4][5][6][7]. A result of this development is a class of mechanical resonators with novel force sensing prospects, thanks to a combination of high force sensitivity, high resonant frequencies, and compatibility with excellent displacement readout.…”

Fractal-like Mechanical Resonators with a Soft-Clamped Fundamental Mode

“…In Fig. 2 we present a simulation of the modes of a resonator made of high-stress stoichiometric silicon nitride film (σ film = 1.14 GPa, E = 250 GPa, ν = 0.23, ρ = 3100 kg/m 3 , 1/φ = 1.4 × 10 3 ) at room temperature [14].…”

Single-Spin Magnetomechanics with Levitated Micromagnets

“…Air damping can be ruled out at our experimental conditions with pressures below 10 −5 mBar and the most likely source of dissipation is the magnet-superconductor interaction. Note that, even though this Q-factor is somewhat lower than what has been demonstrated with non-magnetic optically levitated [16] and nano-fabricated mechanical resonators [40][41][42][43], it represents the state of the art for magnetized resonators [44,45] and the ultimate limit, in particular for magnets with a < µm, is still an open question.…”