final presentation-clinton potts
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Laser Cooling of a Nanomechanical
Oscillator Jasper Chan et. al.
Presented by: Clinton Potts
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Overview
Experimental Motivation
Optomechanics
Sideband Cooling
Nanomechanical Oscillator
Measurement Technique
Results
Future Work 2
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Experimental Motivation
Observe quantum mechanical behavior in a mesoscopic system
Mesoscopic Billions of atoms
Similar work performed using cryogenic cooling techniques
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Solely cryogenic cooling not realizable for many devices
~ OConnell, Nature 464, 697-703 (2010)
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Optomechanics
Crookes radiometer
Photons carry momentum
Radiation Pressure
High finesse cavities increase momentum transfer
Optical field couples to the mechanical motion
Markus Aspelmeyer, Cavity Optomechanics (2013)
www.envirogadget.com
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Optical Resonator
High population of photons at resonant frequency Population quickly drops off
Optical decay rate - Related to Finesse
Markus Aspelmeyer, Cavity Optomechanics (2013)
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Optomechanical Resonator
Optical Cavity consists two mirrors
Fixed Mirror
Movable mirror attached to Spring
Movable mirror act as simple harmonic oscillator
Motion described by phonons
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Sideband Cooling
Non-Sideband Resolved
>
Sideband Resolved
<
7 Markus Aspelmeyer, Cavity Optomechanics (2013)
=
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Phonon-Photon Interactions
Three processes possible
Photon Absorption (Grey)
Phonon Creation (Red, Stokes)
Phonon Annihilation (Blue, Anti-Stokes)
Markus Aspelmeyer, Cavity Optomechanics (2013)
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Ground State Cooling
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To maximize Anti-Stokes scattering
= High Density of States within cavity
Low Density of States outside cavity
=
Markus Aspelmeyer, Cavity Optomechanics (2013)
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Nano-Mechanical Device
Silicon Nanobeam
Device pre-cooled to 20K
Laser coupled via tapered fiber
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Measurement and Results
=
(()2+(
2 )2)
Average number of phonons
Total mechanical damping rate
Measured from transmitted drive laser
Phonon number determined via curve fitting
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Measurement and Results
= . .
Average number of Phonons
Cooling limited by increased bath temperature
Due to high intensity field
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Going Forward
Not a true quantum mechanical measurement Classical measurement of quantum system
Measured average number of phonons Detection of discrete phonon values more direct proof of quantum mechanics
Markus Aspelmeyer, Cavity Optomechanics (2013)
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Questions
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