000178235 001__ 178235
000178235 005__ 20190316235417.0
000178235 0247_ $$2doi$$a10.5075/epfl-thesis-5380
000178235 02470 $$2urn$$aurn:nbn:ch:bel-epfl-thesis5380-7
000178235 02471 $$2nebis$$a7303879
000178235 037__ $$aTHESIS
000178235 041__ $$aeng
000178235 088__ $$a5380
000178235 245__ $$aCavity-Optomechanics with Silica Microtoroids$$bQuantum-Coherent Coupling and Optomechanically Induced Transparency
000178235 269__ $$a2012
000178235 260__ $$aLausanne$$bEPFL$$c2012
000178235 300__ $$a176
000178235 336__ $$aTheses
000178235 520__ $$aHere, I report on a cryogenic cavity optomechanics  experiment that has been set up with the goal to cool a  mechanical degree of freedom of a fused silica microtoroidal  resonator into the quantum regime by means of a combination  of cryogenic and laser cooling. Based on the experience with  a Helium-4 exchange gas cryostat obtained during a previous  cryogenic optomechanics experiment, a novel setup with a  Helium-3 cryostat at its heart has been set up. Cooling of a  mechanical degree of freedom of a microtoroid close to its  motional quantum ground state could be achieved and a regime,  where full quantum control becomes possible, has come into  reach. Silica microtoroids sustain at the same time ultra-high  finesse optical whispering gallery modes (WGM) as well as  radial mechanical modes ("radial breathing modes", RBM). The  two degrees of freedom are mutually coupled, since mechanical  motion changes the optical resonance frequency, and the  mechanical motion is affected by the radiation pressure  forces of an optical field contained in the optical mode. As  the optical cavity lifetime is finite, the intracavity  optical field amplitude is not adjusting instantaneously to  the changed boundary conditions as induced by a mechanical  displacement, but in a retarded manner, which gives rise to  an effect known as dynamical backaction, that for example can  be used to laser cool a mechanical mode. Using a 1550 nm laser important insight has been gained on  the dependency of mechanical decay rate and frequency as a  function of temperature, which is dominated by two level  systems within amorphous fused silica. The different  temperature regimes have been explored, including experiments  at the lowest accessible temperatures, where evidence of  resonant saturable absorption of TLS has been found. Using 780 nm light instead, cooling below ten quanta could  be achieved and "optomechanically induced transparency", the  optomechanical equivalent of electromagnetically induced  transparency as found in atomic vapors, could be  demonstrated, enabling all-optical switching of a laser beam  and storage of pulses. Novel, optimized spokes-supported toroids then enabled us  to push up the optomechanical coupling sufficiently, such  that cooling to below two thermal quanta could be achieved  and —for the first time in the optical domain—  the quantum-coherent coupling regime could be accessed. Here,  the optomechanical coupling rate exceeds the optical and  mechanical decay rates (i.e. "strong coupling"), but also the  mechanical decoherence rate, such that quantum-state transfer  between optics and mechanics comes into reach. In addition, this thesis contains the technological steps  taken and experimental hurdles overcome towards these  experiments.
000178235 6531_ $$acryogenic cavity optomechanics
000178235 6531_ $$ahelium-3 cryostat
000178235 6531_ $$atoroidal silica microresonators
000178235 6531_ $$aresolved sideband regime
000178235 6531_ $$alaser backaction cooling
000178235 6531_ $$aoptomechanically induced transparency
000178235 6531_ $$astrong coupling
000178235 6531_ $$aquantum-coherent coupling
000178235 6531_ $$aoptomécanique en cavité à basse température
000178235 6531_ $$acryostat à hélium-3
000178235 6531_ $$amicrotores de silice
000178235 6531_ $$abandes latérales résolues
000178235 6531_ $$aaction en retour dynamique
000178235 6531_ $$arefroidissement par laser
000178235 6531_ $$atransparence induite électromagnétiquement
000178235 6531_ $$acouplage fort
000178235 6531_ $$acouplage cohérent quantique
000178235 700__ $$0244972$$aWeis, Stefan Alexander$$g202198
000178235 720_2 $$0244694$$aKippenberg, Tobias$$edir.$$g182444
000178235 8564_ $$s13399694$$uhttps://infoscience.epfl.ch/record/178235/files/EPFL_TH5380.pdf$$yTexte intégral / Full text$$zTexte intégral / Full text
000178235 909C0 $$0252348$$pLPQM
000178235 909CO $$ooai:infoscience.tind.io:178235$$pSTI$$pthesis$$pthesis-bn2018$$pDOI$$pSB$$qDOI2$$qGLOBAL_SET
000178235 918__ $$aSB$$cICMP$$dEDPO
000178235 919__ $$aLPQM1
000178235 920__ $$b2012
000178235 970__ $$a5380/THESES
000178235 973__ $$aEPFL$$sPUBLISHED
000178235 980__ $$aTHESIS