Collecting many elements often gives rise to fascinating emergent phenomena that cannot be predicted from the individual elements. Understanding and controlling collective phenomena could potentially lead to the discovery of new properties and functionalities, advancing technologies. My research explores quantum collective phenomena in pristine systems made of ultracold atoms cooled to nano-Kelvin scale temperatures or interacting atoms and photons, utilizing a developed toolbox involving arbitrary potential shaping and tunable interactions.
In this talk, I will introduce two unique approaches that allow for the detailed study of intricate collective phenomena. The first approach utilizes quantum gases confined in an optical box, resulting in homogeneous bulk density and sharp boundaries. I will discuss how, upon triggering instabilities, self-patterned macroscopic structures spontaneously emerge from the homogeneous world, such as never-before-seen vortex dipole necklaces and density crystals. This could open up a way to study connections from quantum fluctuations, primarily seeding those instabilities, to quasiparticle excitations and large-scale structures. The second approach hybridizes an array of single atoms with a common photonic channel. We demonstrate that microscopic control of atoms leads to novel controllability of collectively scattered photons. Furthermore, by overcoming long-standing challenges, we demonstrate for the first time trapped atoms integrated with a two-dimensional nanophotonic circuit and observe atom-light superradiant cooperative coupling. This marks the opening of a new research field that combines the cold-atom toolbox and the rich functionalities of nanophotonic circuits.