Ultrasensitive nano-optomechanical force sensor operated at dilution temperatures

Area of Science:

• Physics
• Materials Science
• Nanotechnology

Background:

• Cooling nanomechanical probes enhances sensitivity by reducing thermal noise and damping.
• Efficient thermalization of nanomechanical systems at low temperatures is challenging due to reduced heat conduction.

Purpose of the Study:

• To investigate the thermalization and dynamics of silicon carbide nanowires at millikelvin temperatures.
• To achieve ultra-high sensitivity in nanomechanical force sensing at dilution refrigerator temperatures.

Main Methods:

• Utilized optomechanical readout techniques in the photon counting regime.
• Employed sub-picowatt optical powers for vibration readout of suspended silicon carbide nanowires.
• Operated within a dilution refrigerator reaching temperatures as low as 32 ± 2 mK.

Main Results:

• Demonstrated successful thermalization of silicon carbide nanowires down to 32 ± 2 mK.
• Achieved force sensing sensitivity of 40 zN/Hz^-1/2.
• Reached sensitivity to lateral force field gradients in the fN·m^-1 range.

Conclusions:

• Optomechanical readout in the photon counting regime enables sensitive nanomechanical measurements at ultra-low temperatures.
• This work paves the way for exploring nanomechanical and thermal properties at minimal excitation levels.
• Enables nanomechanical vectorial imaging of faint forces at dilution temperatures.