Manipulating Disorder-Induced Defect States to Achieve Low Loss Modes

Speaker: 
Ryan Behunin
Seminar Date: 
Friday, March 27, 2015 - 12:00pm
Location: 
BECTON SEMINAR ROOM See map
Prospect Street
New Haven, CT

Abstract: Disorder induced defect states are virtually impossible to avoid in systems ranging from acoustic wave resonators to superconducting cavities. At cryogenic temperatures, such defect states pose a barrier to the realization ultralong lived coherent excitations at microwave-frequencies, crucial for classical and quantum information processing. These defects can interact with a variety of fields (e.g. electromagnetic, acoustic, etc.), absorbing and emitting quanta in much the same way that atoms interact with light. Due to thermal occupancy of quantized energy levels, defect-induced attenuation increases sharply at cryogenic temperatures, stifling the ability to achieve ultra low-loss modes with ground state occupancy. In this talk I will describe experimental and theoretical studies of phonon-active defect states in silica, and discuss techniques to mitigate defect-induced losses. We generate intense phonon fields and interrogate their effect on the ensemble of defects within a fiber optic acoustic waveguide using optical methods. We show that defect-induced dissipation can be manipulated using a strong phonon drive field proximal to frequencies of interest. Our observations, combined with a survey of past experimental studies, indicate that phonon lifetime enhancements by many orders of magnitude are possible in silica. Hence, ostensibly lossy amorphous media (which are among the most superb optical materials) can be transformed into low-loss phononic media. While these studies are carried out in the phononic domain, our findings are quite universal, with implications to cavity optomechanics and superconducting resonators

Host: 
Paul Fleury
Seminar Announcement Brochure: 

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