Alec Douglas - Quantum Science and Engineering Seminar

Title: Quantum Dipoles in Ordered Arrays

Abstract: Ordered lattices of interacting itinerant dipoles provide a powerful setting for creating and controlling collective quantum phenomena. In this talk, Alec Douglas will use an erbium quantum gas microscope to explore this physics across magnetic and optical dipoles, from quantum solids and spin squeezing to collective light–matter interactions.

Douglas will begin with dipolar quantum solids in a Hubbard quantum simulator, where tunneling competes with short- and long-range interactions to produce crystalline density order. He will then describe a novel, broadly applicable method for generating spin squeezing. In a shallow lattice, atomic motion protects spin coherence while magnetic dipole–dipole interactions generate effective all-to-all one-axis-twisting dynamics, producing 7.1 dB of metrologically useful squeezing.

The main focus will be collective optical behavior in an ordered atomic array with subwavelength spacing. In this regime, photon exchange couples the atoms into superradiant and subradiant modes whose emission is strongly enhanced or suppressed by many-body interference. Using site-resolved detection, we uncover the microscopic correlations that govern this collective radiative decay. We then coherently transfer excitations between bright, rapidly emitting modes and dark, long-lived modes, allowing collective excitations to be stored and released into a selected optical mode.

Together, these experiments show how order, motion, and dipolar interactions can be harnessed to create quantum phases, generate entanglement, and control collective emission, opening new directions for programmable quantum matter and quantum-optical interfaces.

Bio: Alexander (Alec) Douglas is an experimental physicist at Harvard University. As an undergraduate, he worked in Mikhail Lukin’s group on diamond-based quantum systems. He later joined Markus Greiner’s group for his Ph.D., where his research has focused on collective phenomena in ultracold atomic systems. His recent work includes realizing spin squeezing through magnetic dipolar interactions and studying superradiance and subradiance in ordered atomic arrays. More broadly, he is interested in using well-controlled atomic systems to study many-body dynamics, generate entanglement, and engineer collective interactions between light and matter.