Physics Department Colloquia |
Events During the Week of March 13th through March 20th, 2016
Monday, March 14th, 2016
- No events scheduled
Tuesday, March 15th, 2016
- No events scheduled
Wednesday, March 16th, 2016
- No events scheduled
Thursday, March 17th, 2016
- From Bell's inequalities to quantum information: a new quantum revolution
- Time: 4:00 pm - 5:00 pm
- Place: 2241 Chamberlin Hall (coffee at 3:45 pm)
- Speaker: Alain Aspect, CNRS, Institut d’Optique
- Abstract: In 1935, with co-authors Podolsky and Rosen, Einstein discovered an intriguing quantum situation, in which particles in a pair are so strongly correlated that Schrödinger called them “entangled”. By analyzing that situation, Einstein concluded that the quantum formalism is incomplete. Niels Bohr immediately opposed that conclusion, and the debate lasted until the death of these two giants of physics.
Thirty years later, John Stuart Bell discovered that it is possible to settle the debate experimentally, by testing the famous "Bell's inequalities", and to show directly that the revolutionary concept of entanglement is indeed a reality. A long series of experiments closer and closer to the ideal scheme proposed by Bell has confirmed that entanglement is indeed "a great quantum mystery", to use the words of Feynman.
Based on that concept, a new field of research has emerged, quantum information, where one uses quantum bits, the so-called “qubits”, to encode the information and process it. Entanglement between qubits enables conceptually new methods for processing and transmitting information. Large-scale practical implementation of such concepts might revolutionize our society, as did the laser, the transistor and integrated circuits, some of the most striking fruits of the first quantum revolution, which began with the 20th century. To cite only the simplest example of these new concepts, quantum cryptography allows one to guarantee an absolute privacy of communications, based on the most fundamental laws of quantum mechanics.
- Host: Thad Walker
Friday, March 18th, 2016
- Gene Surfing and Survival of the Luckiest
- Time: 3:30 pm - 4:30 pm
- Place: 2241 Chamberlin Hall (coffee at 3:15 pm)
- Speaker: David Nelson, Harvard University
- Abstract: It is widely appreciated that population waves have played a crucial role in the evolutionary history of many species. In parallel with Fokker-Planck descriptions of stochastic processes in physics, population geneticists have developed methods for understanding mutations, genetic drift and selective advantage in such situations. Provided number fluctuations at the frontier are taken into account, neutral genetic markers can be used to infer information about growth, ancestral population size and colonization pathways. Neutral mutations optimally positioned at the front of a growing population wave can increase their abundance via a "surfing" phenomenon. Experimental and theoretical studies of this effect will be presented, as well as recent attempts to extend statistical dynamics ideas to microorganisms cooperating and competing in the turbulent environment of the ocean.
- Host: Pupa Gilbert