PhD Defense: Mads Bjerregaard Kristensen

Optomechanical Memory for Light

Mechanical resonators constitute an essential element in emerging quantum technologies. Since such resonators can couple to a range of different degrees of freedom, they are particularly promising in interfacing disparate quantum systems. The recent developments in the design of mechanical resonators with ever decreasing dissipation and quantum-coherent optical control of their displacement has cemented them as a principal element in the toolbox of hybrid quantum systems.

In this thesis, we report the demonstration of a long-lived and efficient memory for light based on an optomechanical cavity, operating at a wavelength in the telecom C-band. We study the storage and retrieval of coherent fields at room temperature, and demonstrate long life-times and reasonable efficiencies, 23 ms and 40% respectively, converting optical information to mechanical excitations by the phenomenon of optomechanically induced transparency.

We extrapolate the demonstrated room-temperature performance to cryogenic conditions, with cautious estimates indicating the feasibility of ground state cooling and the associated quantum coherent storage of light with less than one added noise quantum. Lastly, we show that modest improvements to our platform can enable observing the effects of injecting single photons, as a step towards quantum repeater applications.

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https://ucph-ku.zoom.us/j/6471222864

 Meeting ID: 647 122 2864