Optical backaction-evading measurement of a mechanical oscillator

Area of Science:

• Quantum Mechanics
• Optomechanics
• Nanotechnology

Background:

• Quantum mechanics limits continuous position measurement precision due to measurement backaction.
• The standard quantum limit can be overcome using backaction-evading measurements, which monitor specific motion quadratures.
• Optical interferometry has not yet been used for backaction-evading measurements.

Purpose of the Study:

• To demonstrate continuous two-tone backaction-evading measurement in a cavity optomechanical system.
• To implement this technique in the optical domain using a nanomechanical resonator.
• To show the transition from conventional to backaction-evading measurement and quantify noise reduction.

Main Methods:

• Utilized a cavity optomechanical system with a photonic-crystal nanobeam.
• Cryogenically and optomechanically cooled the nanomechanical mode close to its ground state.
• Employed quantum-limited optical heterodyne detection for continuous measurement.

Main Results:

• Successfully demonstrated continuous two-tone backaction-evading measurement in the optical domain.
• Observed a reduction in total measurement noise by up to 0.67 dB (14%).
• Explicitly showed the transition from conventional measurement to backaction-evading measurement.

Conclusions:

• The study validates the feasibility of backaction-evading measurements in nanomechanical resonators.
• This technique enables ultrasensitive optical measurements of motion and force.
• Paves the way for enhanced precision in quantum measurements using optical methods.