Cooling a mechanical resonator with nitrogen-vacancy centres using a room temperature excited state spin-strain...

Area of Science:

• Quantum physics
• Condensed matter physics
• Nanotechnology

Background:

• Cooling mechanical resonators to sub-thermal states is a significant challenge.
• Optomechanics offers one approach, coupling mechanical modes to optical cavities.
• Coupling resonators to well-controlled two-level systems presents an alternative cooling strategy.

Purpose of the Study:

• To propose and experimentally validate a protocol for dissipative cooling of a room-temperature mechanical resonator.
• To investigate the spin-strain interaction in the excited state of a nitrogen-vacancy (NV) center ensemble.
• To demonstrate the feasibility of cooling a mechanical resonator using NV centers.

Main Methods:

• Coupling a mechanical resonator to a nitrogen-vacancy (NV) center ensemble via spin-strain interaction.
• Utilizing the orbitally-averaged excited state of the NV center ensemble.
• Experimentally measuring and comparing spin-strain coupling strengths in the excited and ground states.
• Theoretically analyzing the cooling potential with a high-density spin ensemble.

Main Results:

• The spin-strain coupling in the excited state of the NV center ensemble was found to be 13.5±0.5 times stronger than in the ground state.
• Experimental validation of enhanced spin-strain coupling in the NV center excited state.
• Theoretical demonstration that this enhanced interaction enables significant cooling of the mechanical resonator.

Conclusions:

• A novel protocol for cooling mechanical resonators using NV centers has been successfully proposed and experimentally supported.
• The enhanced spin-strain coupling in the NV center excited state is key to achieving efficient cooling.
• This method offers a promising pathway for cooling mechanical resonators from room temperature to a fraction of their thermal phonon occupancy.