CLEO covid conferencing

I attended (virtually) the CLEO/Europe conference last week. It's been said many times before by others, but networking and informal discussions which often lead to new creative lines of research do not occur to any significant extent at online conferences. The one silver lining is that when things return to normal, conferences will hopefully be run in a hybrid mode enabling those unable to attend in person to at least view talks remotely.

Some of the interesting talks I saw:

Fabio Sciarrino from Sapienza University of Rome gave an overview of Boson Sampling and discussed his group's recent work on using thermoelectric tuning of a laser-written waveguide array to create a semi-programmable Boson Sampling device. This aims to overcome the main limitation of the recent Chinese photonic quantum supremacy experiment (that their device is not programmable). The preprint is available here.

Vera Neef from Rostock University discussed the generation of non-Abelian geometric phases using two photon quantum states propagating through an adiabatically-modulated array of four coupled waveguides. The approach can be extended to photonic simulation of quantum chromodynamics.

Christophe Galland from EPFL gave an overview of his group's recent work on molecular optomechanics and nanocavities. The former is an interesting platform for observing quantum coherent effects at room temperature, by using a laser beam to excite a high frequency vibrational resonance of a molecule; Raman scattering can then be used to probe the resulting vibrational quantum states.

Nathan Goldman from Universite libre de Bruxelles presented a scheme to detect fractional quantum Hall states of bosons. The idea is to prepare a few-body ground state of bosons in a topological (Chern) band trapped by a confining potential, turn off the confining potential, and then apply a uniform acceleration. The resulting transverse Hall shift exhibits quantized plateaus which can be used to measure the many-body Chern number. For larger numbers of bosons, density measurements can be used to obtain the Chern number. The study was published in PRA last year. These effects could be probed using superconducting qubits using an approach similar to this paper, but with a larger lattice and more photons.

Christina Jörg from Pennsylvania State University discussed the creation of bound states in the continuum in photonic crystals using tailored environmental coupling. By embedding a photonic crystal in a suitably-designed thin photonic crystal cladding, one can create bound states in the continuum above the diffraction limit (i.e. with a volume larger than the operating wavelength). The preprint is available here.