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Leonard Mandel (1927–2001)

2001; Nature Portfolio; Volume: 410; Issue: 6828 Linguagem: Inglês

10.1038/35069190

1476-4687

G. S. Agarwal, Z. Y. Ou,

Molecular spectroscopy and chirality

Leonard Mandel, one of the founding fathers of quantum optics, died at his home on 9 February at the age of 73.Our generation of optical scientists grew up learning from Mandel's work: quite literally, he showed us the light by opening up many new avenues of research.He was an elegant experimentalist and a celebrated theorist.Echoes of his unmistakable slow but clear voice will continue to remind us of the contributions of this remarkable man.Mandel was born in Berlin, but moved to Britain when he was a boy.He was educated at the University of London, studying cosmic rays for his PhD, which was awarded in 1951.After a short spell in industry, Mandel took up an academic post at Imperial College, London.It was the investigation of cosmic rays that eventually led him to discover what is today known as Mandel's photon-counting formula, which relates the statistical properties of arbitrary optical fields to those of photoelectrons detected experimentally.Mandel worked throughout his career to perfect the photon-counting technique for studying a variety of optical fields, from the thermal light of a candle to sophisticated quantum sources.In the 1960s, this work enabled physicists to understand the statistical properties of lasers operating under different pumping conditions.Such studies gave support to the quantum theory of the laser.Mandel performed his first major experiment at Imperial, its simplicity in design becoming one of his trademarks.The result, typically, was counterintuitive.The experiment showed how interference between independent photon beams can be observed and that such a possibility is permitted by quantum physics.His demonstration of two-photon interference followed.This was an experiment that laid the foundation for later work on quantum entanglement, a concept of state superposition first introduced by Erwin Schrödinger.In 1964 Mandel settled permanently in Rochester, New York, having been persuaded to move there by Emil Wolf.Wolf and Mandel wrote several notable papers together, and also organized the Rochester Conferences on Quantum Optics, which laid the foundations of the field and continue to this day.It was at one of the early conferences that debate really began to heat up on the need for a quantum theory of light, and Mandel started to devote much of his research