Abstract

Measurements involving the phase of a light beam are employed in a variety of fields such as interferometry, phase contrast imaging, holography, coherent signal processing, quantum nondemolition measurements and quantum gates. It is, thus, of fundamental concern to examine the influence of a single emitter on the phase of a light beam. Usually this is performed using a high-finesse cavity coupled to the single emitter in order to greatly enhance the inherently small effect. However, recently we showed that a single naked molecule can attenuate and amplify a focused laser beam substantially [1-3]. Considering that coherent scattering of light by an oscillator is accompanied by a phase shift, these observations imply that a single emitter should also be able to shift the phase of a laser beam. Indeed, a phase shift measurement of 1° on a single atom in a trap has been recently achieved [4]. Here we report on a phase shift measurement of 3° imprinted on a laser beam by a single molecule in the solid state. We also show the realization of a single-molecule electro-optic modulator and discuss applications of our work in microscopy and signal processing [5]. Utilizing a direct focusing geometry (i.e. without a cavity) can be attractive both in terms of its fundamental simplicity as well as in terms of practical integration and application.

© 2011 IEEE