Hi all, 

The next Optical Sciences seminar will be given by Neel Mackinnon from the Quantum Theory group at 3pm on Thursday 9th May in 222. Neel will be presenting the following: 

Title: Electromagnetic Helicity within a Chiral Medium

Abstract: The electromagnetic helicity is a locally conserved quantity of the free electromagnetic field which, in a sense, describes the “handedness” of the field. The name “helicity” can be justified by the fact that the total helicity of an electromagnetic field, integrated over all space, is proportional to the difference in the number of left- and right-handed circularly polarised photons in the field. The concept of helicity can also be made meaningful in presence of matter – in this case it is no longer conserved, but charges and currents may act as sources or sinks of helicity. The definition of helicity can then be very straightforwardly extended to apply within dielectrics. 

However, this straightforward extension runs into difficulties if the dielectric material is chiral (that is, if it can exhibit optical rotation). This talk will introduce some of the features of electromagnetic helicity, and describe a proposed modification to the definition of the helicity density within a chiral medium.

The talk will last around 20 minutes, followed by coffee and biscuits in the common room. 

Hope to see you there,

Frances