Superatom Waveguide Quantum Electrodynamics

The past decade has seen remarkable advances in the field of quantum non-linear optics, where individual photons are made to strongly interact which each other. Such strong photon-photon interactions are of both fundamental and technological interest: They are the prerequisite for implementing deterministic quantum logic gate operations for processing optical quantum information. Moreover, photons that strongly interact via a quantum nonlinear medium exhibit complex out-of-equilibrium quantum dynamics that enable one to tailor and control the photon statistics of light. Quantum non-linear effects have been successfully demonstrated with few photons in a number of experimental platforms, which exploit resonant enhancement of emitter-photon coupling via high-finesse optical cavities, collective response of ensembles of strongly interacting Rydberg atoms, so-called superatoms, or efficient coupling of single quantum emitters to guided light in the realm of waveguide quantum electrodynamics (QED). However, it remains a formidable challenge to reach the true many-body regime of quantum non-linear optics, where strong interactions and entanglement between many photons and many quantum emitters give rise to exotic quantum phases of light, such as photonic molecules or fermionic subradiant states. The objective of SuperWave is to realize this regime by synergizing superatoms and waveguide QED. By uniting the expertise and experimental methods of three teams that have previously driven these fields independently, we will develop near-ideal fiber-coupled nonlinear quantum devices. Their implementation will mark a major breakthrough in quantum optics and constitute a key resource in quantum sensing, quantum metrology, quantum communication, as well as quantum simulations. We will illustrate this great potential through a number of hallmark experiments such as the coherent fragmentation of a classical light pulse into its highly nonclassical photon number components.