cordially invites you to join* meet.google.com/bhy-jgpb-buq
to attend a General Lecture on
17 August 2020 at 7:00 PM
Prasanta Kumar Basu
Retired Professor, Institute of Radio Physics and Electronics,
University of Calcutta
Abstract: Satyendra Nath Bose, with Einstein’s help, published two papers in Zeitschrift fur Fysik in 1924. His theory could explain Planck’s radiation law without any ad hoc assumptions. Thus came Bosons, with photons as a member, as a quantum particle. Einstein used Bose’s statistics to propose a new phase, leading to Bose Einstein Condensation (BEC), in which all bosons having integer spin, condense into the lowest lying phase coherent state. The idea was experimentally verified during 1990’s with Rd+ and Na+ atoms cooled to micro Kelvin temperature. For their work, Cornell, Weiman and Ketterle got Nobel Prize in Physics in 2001.
Excitons in semiconductors are electron-hole pairs bound by Coulomb interaction as in a H atom and have bosonic character. Since 1960’s, they were considered as a suitable candidate to observe BEC at room temperature and above. The search intensifies after 2000. Finally BEC is observed in a semiconductor microcavity structure in 2006. The highly coherent state made of excitons gives a coherent emission of photons like lasers, requiring less input power. The laser, called the polariton laser, operates at room temperature with electrical input and is expected to play a role in current and future information technology.
The webinar aims mainly to give historical sketches, and to explain the technical terms in simple language to persons even with knowledge in higher secondary physics.
Prasanta Kumar Basu (B.Sc. Hons Presidency College), B. Tech, M.Tech and Ph.D. all in Radio Physics and Electronics, joined the RPE department of CU as a Lecturer in 1971. His research has been in semiconductors, he is an Alexander von Humboldt fellow and he worked as Visiting Professors in McMaster University, Canada and in TIFR. He was in several administrative positions in RPE department. After his retirement from CU in 2011, he worked as a UGB BSR Faculty fellow, then as Visiting Professor in IIT KGP and finally as an investigator in a joint Indo Taiwan project. Since 2019, he is engaged in honorary collaborative research in RPE, and in completing his fourth book Semiconductor Nanophotonics to be published by OUP, Oxford, soon.
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