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Two emerging fields of research will be addressed: the quest for macroscopic quantum superpositions and the experimental study of solid-state cavity quantum electrodynamics.
Concerning the first topic an experiment is discussed that aims at transferring a superposition of a photon propagating in two directions after passing a beamsplitter into a superposition of two center-of-mass motions of a tiny mirror that is placed in one path of the beamsplitter. Based on current state-of-the-art experimental techniques a scheme is proposed that can lead to a quantum superposition about 10 orders of magnitude more massive than any superposition demonstrated to date. A crucial part of the proposed experiment is an optical cavity with one end mirror as small as 10 micrometers in diameter attached to a high Q mechanical cantilever. We demonstarte such a system. Aligning this mirror as part of a 25mm optical cavity in vacuum resulted in an optical quality factor of 2.000 and a mechanical quality factor of 100.000. This provides an excellent interferometric position and motion measurement of the cantilever/mirror system. We use this readout to measure the thermal motion and to feed-back an optical force to counteract the thermal motion of the center-of-mass mode. Experimental results will be shown that demonstrate the optical cooling from room temperature to below 1 Kelvin.
Concerning the second topic, initial experimental progress in solid-state cavity QED have led us to the unexpected observation of ultra low threshold lasing of a photonic crystal defect mode cavity embedded with only 1 to 3 InAs self-assembled quantum dots as gain medium. Photon correlation measurements confirm the transition from a thermal light source to a coherent light source. |
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