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Scientific result | Photonics

A Single Photon Emitter Detects the Movement of an Oscillator

A team of scientists has managed to couple a semiconductor quantum dot and a vibrating wire. The quantum dot detects the mechanical oscillations of the wire with high sensitivity. This work, completed as part of a collaboration between the University of Basel and INAC, opens new perspectives for the development of original sensors and for fundamental studies.

Published on 17 July 2017

A quantum dot is a semiconductor nanostructure that typically measures
 ten nanometers, with optical properties similar to those of an atom. These devices are commonly used in quantum optics studies for several purposes, including to generate light pulses containing exactly one photon. In this study, a quantum dot was used to finely probe the movement of a mechanical oscillator.

For this purpose, the dot was directly integrated at the base of the oscillator—a vertical wire ten micrometers high. When the latter vibrated, the box was subjected to an oscillating deformation, which modulates the gap between its energy levels, and consequently, the color of emitted photons. Using optical spectroscopy to precisely measure these variations makes it is possible to solve the thermal vibrations of different mechanical modes of the wire at cryogenic temperature, i.e. vibration amplitudes of the order of one hundred femtometers (10-13 m).

This study paves the way for the development of new sensors. Moreover, since the coupling between the quantum dot and the wire works in both directions, the quantum dot is able to set the oscillator in motion, despite the fact that it's a thousand times smaller

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