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Einstein’s Light Quanta: Then and Now
Prof. A. Douglas STONE, Carl A. Morse Professor of Applied Physics and Physics, Yale University
Date : 5 Dec 2019 (Thursday)
Time : 3:30 - 5:00 pm
Venue : Kaisa Group Lecture Theater (IAS LT), Lo Ka Chung Building, Lee Shau Kee Campus, HKUST


EINSTEIN is well known for his rejection of quantum mechanics in the form it emerged from the work of HEISENBERG, SCHRÖDINGER, BORN and DIRAC in 1926-1927. Much less appreciated are the many seminal contributions he made to quantum theory prior to his final scientific verdict: that the theory was at best incomplete. His many key conceptual innovations leading to the emergence of modern quantum theory place him as an arguably central figure. In this lecture, the speaker will focus on Einstein’s introduction of the idea of quanta of light in 1905, the beginning of the photon concept in physics. Between 1905 and 1917, Einstein showed rigorously that electromagnetic radiation has both a particle and wave nature, and laid the foundation for the quantum theory of radiation by introducing the concepts of spontaneous and stimulated emission between atomic energy levels. He also showed that the emission of individual quanta must be directional and carried both energy hν and momentum, hν/c. His arguments that these quanta were fundamental new entities in physics was not accepted until the experimental measurement of Compton scattering in 1925. In modern physics we recognize Einstein’s quanta as photons, fundamental force-carrying bosons in the Standard Model. However, full control of the photon Hilbert space has only been achieved quite recently through advances in quantum optics and quantum information physics. The speaker will sketch these recent advances and explain how cavity quantum electrodynamics (QED) and circuit QED have allowed the creation of non-classical photon states which were impossible to realize until quite recently. These states are currently being exploited for quantum storage and information processing with hardware-efficient error correction.


About the speaker

Prof. A. Douglas Stone received his PhD in Physics from Massachusetts Institute of Technology in 1983. After his post-doctoral studies, he joined the Yale University in 1986 and is currently the Carl A. Morse Professor of Applied Physics and Physics there.

Prof. Stone is a theoretical physicist with interests in solid-state and optical/laser physics. Specifically, he is interested in theoretical issues relating to physics and electronics on the nanoscale and in micro-lasers and other optical devices for integrated optics, which he analyzes using the tools of quantum and electromagnetic theory and non-linear dynamics (chaos theory).

Prof. Stone was the recipient of the Willis E. Lamb Award for Laser Science and Quantum Optics for his work on random and chaotic lasers (2015) and the Phi Beta Kappa Award in Science for his book "Einstein and the Quantum: The Quest of the Valiant Swabian" (2014). He was also elected a Fellow of Optical Society of America (2010), a Fellow of American Physical Society (1993) and the Alfred P. Sloan Fellow (1990).


For attendees’ attention


  Seating is on a first come, first served basis.
  Light refreshments will be served from 5:00 to 5:30 pm.



HKUST Jockey Club Institute for Advanced Study
Enquiries: ias@ust.hk / 2358 5912