Theoretical seminar | 22 July 2020

Typically, the stationary states of a physical system inherit the symmetries of the laws that govern the system, i.e., the symmetries of the Hamiltonian or Lagrangian. Interestingly, a physical response is not always constrained by the Hamiltonian symmetries, as a symmetry can be hidden or alternatively spontaneously broken. In this talk, I will present examples of elementary classical and quantum systems with hidden or spontaneously broken symmetries, and discuss how hidden symmetries may lead to nonreciprocal optical responses with no external bias in the quantum realm.