Atomic force microscopy

Physics

Thermalisation

Nanotechnology

Optical force

Optomechanics

Mathematics

Resonator

Optics

Refrigerator car

Mathematics education

Engineering

Nanomechanics

Microscale chemistry

Atomic physics

Photon

Composite material

Thermal conduction

Chemistry

Materials science

Optical tweezers

Sensitivity (control systems)

Electronic engineering

Oscillation (cell signaling)

Dilution refrigerator

Optoelectronics

Biochemistry

Nanowire

Thermodynamics

Nature Communications

Cooling down nanomechanical force probes is a generic strategy to enhance their sensitivities through the concomitant reduction of their thermal noise and mechanical damping rates. However, heat conduction becomes less efficient at low temperatures, which renders difficult to ensure and verify their proper thermalization. Here we implement optomechanical readout techniques operating in the photon counting regime to probe the dynamics of suspended silicon carbide nanowires in a dilution refrigerator. Readout of their vibrations is realized with sub-picowatt optical powers, in a situation where less than one photon is collected per oscillation period. We demonstrate their thermalization down to 32 ± 2 mK, reaching very large sensitivities for scanning probe force sensors, 40 zN Hz −1/2 , with a sensitivity to lateral force field gradients in the fN m −1 range. This opens the road toward explorations of the mechanical and thermal conduction properties of nanoresonators at minimal excitation level, and to nanomechanical vectorial imaging of faint forces at dilution temperatures.

Ultrasensitive nano-optomechanical force sensor operated at dilution temperatures