Download Optomechanics Experiments

Optomechanics Experiments
Radiation Pressure Rules
MIT Quantum Measurement Group
Quantum optomechanics
 Techniques for improving gravitational wave
detector sensitivity
 Tools for quantum information science
 Opportunities to study quantum effects in
macroscopic systems
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Observation of quantum radiation pressure
Generation of squeezed states of light
Entanglement of mirror and light quantum states
Quantum states of mirrors
Optomechanical coupling
 The radiation pressure force couples the
optical field to mirror motion
Quantum
Classical
 Alters the dynamics of the mirror
 Spring-like forces  optical trapping
 Viscous forces  optical damping
 Tune the frequency response of the GW
detector
 Manipulate the quantum noise
 Quantum radiation pressure noise and the
standard quantum limit
 Produce quantum states of the mirrors and
light
Optomechanical coupling:
Radiation pressure forces
 Detune optical field from cavity resonance
 Change in mirror
position changes
intracavity power
 radiation pressure
exerts force on mirror
 Time delay in cavity
results in cavity
response doing work
on mechanics
Gram-scale mirrors
Experimental cavity setup
1m
10%
90%
5W
Optical fibers
Coil/magnet pairs
for actuation (x5)
1 gram
mirror
Trapping and cooling
 Stable optical trap
with bichromatic light
 Dynamic backaction
cooling
Stiff!
Stable!
T. Corbitt et al., Phys. Rev. Lett 98, 150802 (2007)
The experiment grows
Vacuum
fluctuations
Squeezed
T. Corbitt et al., Phys. Rev. A 73, 023801 (2006)
 Two identical cavities with 1 gram mirrors at the ends
 Common-mode rejection cancels out laser noise
The experiment grows
Optically trapped and cooled mirror
Optical fibers
Teff = 0.8 mK
N = 35000
1 gram
mirror
C. Wipf, T. Bodiya, et al. (March 2010)
That elusive quantum regime
Thermal noise
Radiation pressure
noise goal (5 W
input)
C. Wipf, T. Bodiya, et al. (Feb. 2011)
Ponderomotive Squeezing
7 dB or 2.25x
Squeezing
T. Corbitt, Y. Chen, F. Khalili, D.Ottaway, S.Vyatchanin, S. Whitcomb, and
N. Mavalvala, Phys. Rev A 73, 023801 (2006)
Cryogenic microgram-scale
mirrors
Thomas Corbitt @ MIT (but soon LSU)
Micromirror oscillators
 AlGaAs layers forming a
Bragg mirror
 ~ 1 to 5 mm long, ~10 μm
supports, 50 to 100 μm
mirror pads
 Fundamental
frequency ~ 200 Hz
 Q factor ~ 2x105 at 5 K
 Mass ~ 250 nanograms
 Reflectivity ~ 99.982%
 Very fragile
 Power handling:
breaks at >100 mW of
incident power
Fabricated by Garrett Cole at Univ. of Vienna
Experimental layout
Noise budget
What can we learn?
 Verify models of radiation pressure noise,
squeezed radiation pressure noise, sub-SQL
topologies
 Verify models of thermal noise (ability to
measure thermal noise as function of both
frequency and temperature across broad
bandwidth in monolithic structure)
 Characterize materials and understand
dissipation mechanisms
 Gain experience in low vibration cryogenics
Amazing cast of characters
MIT
Collaborators
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Thomas Corbitt
Christopher Wipf
Timothy Bodiya
Sheila Dwyer
Lisa Barsotti
Nicolas Smith-Lefevbre
Eric Oelker
Rich Mittleman
MIT LIGO Laboratory
Yanbei Chen & group
David McClelland & group
Roman Schnabel & group
Stan Whitcomb
Daniel Sigg
Caltech 40m Lab team
Caltech LIGO Lab
Garrett Cole of Aspelmeyer
group (Vienna)
 LIGO Scientific
Collaboration