Biographical Memoirs Volume 87 (2005) / Chapter Skim
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Leonard Mandel
Leonard Mandel
Pages 274-293
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From page 275... ...
He is widely credited with being one of the founding fathers of the field of quantum optics, which sprung from the marriage of quantum mechanics and optics in the 1960s into one of the most exciting areas in modern science. He made seminal contributions to experimental and theoretical problems of optical coherence, laser physics, and quantum optics, including laser phase transitions, locality violations in optics, tests of quantum mechanics, and nonclassical states of light.
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From page 276... ...
Over the course of his career Leonard devised ingenious experiments to explore the quantum statistics of light and thereby to advance profoundly our understanding of its quantum character. In 1977 Leonard's quest led to the pioneering demonstration of the manifestly quantum, or "nonclassical," nature of light by way of the first observation of photon antibunching, here for the fluorescent light from a single atom.
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From page 277... ...
Leonard showed that Dirac's well-known statement about single-photon interference must be modified to assert that "in fourth order interference, a pair of photons interferes only with the pair itself." In a classic experiment with photon pairs in 1995 he demonstrated with brilliant clarity a central tenet of quantum mechanics, namely, that there is no physical reality for elemental quantum processes in the absence of a measurement. Leonard's ability to identify critical issues and make their consequences manifest are evidenced in many other important contributions to both classical and quantum optics.
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From page 278... ...
Back in London, Leonard attended the William Ellis School, a distinguished boy's grammar school, where he excelled academically and also became the most honored student in the school (as the head boy)
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in only three years, graduating from Birkbeck in 1951 with a thesis titled "Interactions of Non-Ionizing Cosmic Ray Particles." He was always grateful to Paul George for giving him the freedom to work on his own ideas in his own way. Throughout his own career Leonard enabled his students by entrusting them with the same faith and confidence in their abilities that George had shown in him.
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They excelled at playing doubles in table tennis, enjoyed ice skating together, and did very well in ballroom dancing. Their daughter, Karen Rose, was born in 1956, followed by a son, Barry Paul, in 1959.
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From page 281... ...
It was a difficult decision for the family to leave England for the United States, but in 1964 Leonard left Imperial College to become professor of physics at the University of Rochester, where he remained until his death in 2001. PROFESSIONAL HISTORY Although Leonard's initial research had been in nuclear physics, his interest in optical coherence was stimulated by the Brown-Twiss experiment in 1956.
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From page 282... ...
Davidson, D Meltzer, and others were among the first to carry out basic experiments to elucidate the coherence properties of the laser in the transition from incoherent to coherent emission around threshold.6,7,8 Carried forward by several successive generations of graduate students, these early studies of the light from a single-mode laser grew over the ensuing decades into diverse investigations of more complex laser behavior, including mode correlation and competition in ring lasers, and optical bistability and firstorder phase transitions in dye lasers.7,8 Although quantum theories are sufficient to understand
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From page 283... ...
Beyond being simply a matter of semantics, such nonclassical fields are required to achieve measurement precision beyond the standard quantum limits, and more generally form the basis for advances in quantum information science related to quantum computation and communication. In further investigation of nonclassical light, Leonard recognized in the early 1980s the tremendous potential associated with the process of parametric down conversion, in which a single pump photon is split into a pair of "daughter" photons.
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From page 284... ...
Y Zou, he systematically explored other aspects of quantum entanglement, including phase memory due to entanglement with the vacuum,20 frequency entanglement to produce spatial quantum beating,21 and phase entanglement to achieve nonlocal interference in separated photon channels.22 With these advances, Leonard played a pioneering role in laying the foundations for modern research in quantum optics and quantum information science, including for Bellstate detection to enable diverse tasks, such as quantum teleportation of the polarization state of single photons.
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From page 285... ...
Monken made a striking demonstration of one of the most unsettling aspects of the quantum realm, namely, that there is no physical reality in the absence of a measurement.25 Regrettably, it has not been possible in this biography to offer more than these few glimpses into the set of topics encompassed by Leonard's remarkable career.7,8 We might just mention that in addition to the study of nonclassical fields, he was also deeply interested in the question of quantum phase for the electromagnetic field and, together with his students A Fougeres and J
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From page 286... ...
Bigelow he initiated a new line of research related to nonclassical states for a collection of atomic spins, which led to one of the first demonstrations of "spin squeezing,"28 thereby helping to initiate what is by now a very active area of research worldwide. Leonard supervised the thesis research of 39 students, many of whom subsequently became leading figures in diverse areas of science and technology.
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From page 287... ...
In 1992 he received the university's Faculty Award for Graduate Teaching. Leonard published about 300 papers, was the coauthor with Emil Wolf of a comprehensive book of more than 1,100 pages entitled Optical Coherence and Quantum Optics,7 and was the coeditor of several conference proceedings.
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From page 288... ...
Mandel. Correlation measurements of laser beam fluctuations near threshold.
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Mandel. Optical communication channel based on coincident photon pairs.
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Mandel. Experimental demonstration of the violation of local realism without Bell inequalities.
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From page 291... ...
Rev A 18:201-207. 1979 Sub-Poissonian photon statistics in resonance fluorescence.
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From page 292... ...
Experi mental demonstration of the violation of local realism without Bell inequalities.
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