Wednesday, December 8, 2010

Tinkham passed away

Tinkham is famous for his work and his book in superconductivity. He passed away last month. Here is an obituary from Nature: [Nature: 468, 766]

This spectacular role in the early history of the BCS theory behind him, Tinkham continued to work with far-infrared spectroscopy but also began to study the macroscopic quantum behaviour of superconductors. Quantum mechanics is normally thought of as important only in the microscopic world of atoms, but in superconductors it manifests itself in very large objects, such as in the superconducting magnets used in magnetic resonance imaging. After Tinkham took up a professorship in 1966 at Harvard University in Cambridge, Massachusetts, one question emerged that remained of central interest to him: what is the nature and origin of resistance in a superconductor? Or put more simply, when is a superconductor really a superconductor?

As it turns out, when superconductors are carrying a current, they don't stay in a fixed macroscopic quantum state, but cascade down from one energy level to another. As energy is lost with each transition, this is equivalent to saying that superconductors have resistance, although it is extremely small under most conditions. In the latter stages of his career, Tinkham was examining the conditions under which these transitions happen and how they happen in very thin wires of a superconductor.

Despite all these achievements, being elected to the US National Academy of Sciences and winning the prestigious Oliver E. Buckley prize of the American Physical Society, Mike was a modest man with an exceptional sense of humour. The same legions of students who witnessed his alchemy with data will remember how they first knocked nervously on his door to be greeted by a somewhat gruff “Come in”, only to learn that he was a very warm and witty mentor.

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