34th Hanan Rosenthal Memorial Lecture

November 1, 2007

The Yale Physics 34th Hanan Rosenthal Memorial Lecture will be given November 16, 2007 by Professor Jean Michel Raimond of the Université Pierre et Marie Curie, Paris France.

Friday, November 16, 2007 - Quantum jumps of light

Photons are indefatigable information carriers, crossing the Universe at the speed of light or delivering data in optical fibers. Photo-detectors count them one by one. This exquisitely sensitive detection is usually rather brutal. Photons are destroyed, their energy being converted into an electrical (or chemical) signal. Photons expire while delivering their message! This destruction is not required by quantum theory. It allows for  transparent detectors that could register a photon without absorbing it. A light quantum trapped in a ‘photon box’, like that proposed by Einstein in a famous thought experiment, could be ‘seen’ many times.

We have realized a non-demolition photo-detection for a microwave field stored in a very high quality superconducting cavity. The ‘transparent probes’ are circular Rydberg atoms. They behave as microscopic atomic clocks. They cannot emit or absorb photons, but their ticking rate depends upon the field intensity. Their ‘time’ reveals the photon number (from zero to seven).

With hundreds of detections over the cavity storage time, we have witnessed the birth, life and death of individual photons, observing for the first time the quantum jumps of light. This experiment realizes an ideal quantum measurement and directly illustrates  all basic quantum postulates (state collapse, statistical results and repeatability). It also leads to the efficient preparation of highly non-classical states of light for fundamental decoherence studies at the quantum/classical border.

The Hanan Rosenthal Memorial Lecture was established in honor of physicist Hanan Rosenthal, a brilliant graduate student at Columbia University and instructor at Yale. This annual lecture in atomic physics, Rosenthal’s field, is given by a distinguished leader in the field. Originally, the lecture series alternated between Columbia and Yale, which were both significant in Hanan Rosenthal’s career; in recent years, the lecture has been held only at Yale University.

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