Latest Incubator Explores the Emerging Connections between Quantum & Classical Optics
Tanya Malhotra, University of Rochester
The OSA Incubator Emerging Connections: Quantum & Classical Optics aims to identify and characterize the links and differences between the fields of classical and quantum optics. This meeting commenced today on Nov 7, 2016 at Washington DC and is hosted by Joseph Eberly, Department of Physics and Astronomy at University of Rochester, USA; Elisabeth Giacobino, CNRS, Laboratori Kastler Brossel, France; Gerd Leuchs, University of Erlangen and Max-Planck Institute for the Science of Light, Germany and Nick Vamivakas, Institute of Optics, University of Rochester, USA.
Classical optics and quantum optics are different theories that help us understand the behavior of light at different scales of light-matter interaction. For example, a typical quantum optics experiment uses single photon sources and detectors. Recent experiments and newer perspectives of coherence and entanglement are redefining how those notions get associated with classical and quantum optics. By mathematically considering the electric field vector of an optical beam as a multi-particle quantum state, standard mathematical tools (such as Bell’s inequality, Schmidt decomposition, statistical correlations, and complementarity) from quantum optics and quantum information theory can be applied to classical beams. The goal is not to mimic the features of quantum optics in classical fields but to find newer perspectives as well as novel applications in classical optics to imaging, microscopy and metrology.
Presentations earlier in the day explored the grey zone at the border of classical and quantum optics. Entanglement has been traditionally associated with the quantum nature of light even though, mathematically speaking, entanglement is simply the nonseparability of sums of product states in a joint function space. This gives rise to the possibility of ‘classical entanglement,’ the subject matter of the discussions throughout the day. Bell’s measure was recalled to be a measure that quantifies entanglement and with the experimental implementation of classical entanglement, the violation of Bell’s inequality can no longer be used to define the border for classical- quantum optics. Similarly, in another talk during the morning, it was shown that the presence of plank’s constant, ħ, in an equation could also not be used as a ‘key’ identifier or a requisite for an equation to describe a quantum phenomenon! By lunch, it was established that entanglement is not a classical or quantum phenomenon but rather is a mathematical property that can be a feature of both classical and quantum optics. It was also pointed out in discussions that unlike quantum entanglement, classical entanglement is strictly local. One of the applications discussed for classical entanglement was for fast kinematic sensing -- a GHz rate detection scheme based on measuring stokes parameters of a radially polarized classical light beam when the object of interest was flown across the beam.
Additionally, a presentation described the recent formulation of a generalized definition of coherence based on understanding the correlations between different sectors (degrees of freedom) of an optical beam. Discussions were extended to include the role of coherence and complementarity in entanglement. It was proposed through rigorous derivation in one of the talks that classical entanglement helps in the complete understanding of complementarity (wave-particle duality).
Stay tuned for more interesting discussions to come from tomorrow’s talks!
Host Nick Vamivakas – Institute of Optics, Rochester University, USA – opens up the meeting with a bit of background about the goals of the Incubator.
Wolfgang Peter Schleich – Universität Ulm, Germany – discusses the emerging connections between classical & quantum optics… and Max Planck.
