## Saturday, December 29, 2018

### Roy Glauber: 1925-2018

I was just told that my former colleague Roy Glauber passed away on the Boxing Day, at age of 93 which is a respectable number.

The Improbable Research remembers him as a janitor at the Ig Nobel Prize ceremonies (focusing on paper airplanes) but aside from that important work, he has done some other things in his life as well, e.g. having won the 2005 Non-Ig Nobel Prize. See also The Optical Society for some memories and data.

I remember Roy Glauber from a few dinners at Harvard – and from the celebration of his Nobel Prize. The Nobel Prize was stolen in 2010.

He has defined the coherent states – that phrase was accepted after his paper in the 1960s. In this way, he clarified the relationships between the fields of optics and quantum optics, between electromagnetic waves and photons (see my explanations how the fields and particles emerge in the classical limit), and described the differences between coherent light (e.g. from lasers) and incoherent light (e.g. from light bulbs). That work was done more than 50 years ago. But it has led to important contemporary applications, e.g. codes in quantum cryptography.

It's funny to realize how much some cutting-edge developments such as "codes in quantum cryptography" depend on insights of someone who was already this old – but who was still around a week ago.

His approach to all these issues was arguably "less systematic" than the approach of those of us who have the particle physics background – despite the fact that he used to teach quantum field theory courses, too. But he just did the important things right and soon.

In 2006, as graduate students noticed, extraterrestrial loop quantum feminists landed at Harvard. Roy Glauber, a skillful vampire, was somewhat helpful in neutralizing them after he ate one of them. At least the superhero who finally saved the university thinks that Glauber's assistance was helpful.

Glauber's name appears in a dozen of TRF blog posts.

RIP, Prof Glauber.