A team of researchers led by Dominik Schneble, a professor in the Department of Physics and Astronomy at Stony Brook University, has made significant advancements in the field of quantum optics. Their research explores cooperative radiative phenomena, shedding light on a longstanding problem that dates back 70 years. The study, which reveals previously unseen collective spontaneous emission effects in synthetic atom arrays, is published in Nature Physics alongside a theoretical paper in Physical Review Research.
Spontaneous emission occurs when an excited atom transitions to a lower energy state, emitting a photon. R.H. Dicke, a physicist from Princeton, theorized in 1954 that introducing another unexcited atom nearby would alter the probability of finding an excited atom. This scenario results in superradiance and subradiance depending on whether the atoms are in phase or opposite phase.
Schneble's team utilized ultracold atoms within a one-dimensional optical lattice to create arrays of synthetic quantum emitters that decay through slow atomic matter waves rather than photons traveling at light speed. This allowed them to explore novel regimes of collective radiative phenomena.
The researchers prepared and manipulated emitter arrays with varying interaction phases to demonstrate directional collective emission and studied dynamics involving retardation and super- and subradiant states. "Dicke’s ideas are of great significance in quantum information science and technology (QIST)," Schneble noted, emphasizing efforts to harness these phenomena for technological applications.
In their experiments, the team achieved unprecedented control over subradiant states, enabling them to shut off spontaneous emission and observe radiation behavior within the array. This represents a first-of-its-kind demonstration according to Schneble.
Former PhD students Youngshin Kim and Alfonso Lanuza contributed significantly to this work. Kim highlighted how neighboring emitters need time to communicate for collective decay from a superradiant state containing a single excitation to occur.
Lanuza described the theoretical challenges involved as akin to a complex game involving atoms exchanging photons and photons getting trapped between atoms. Despite these complexities, he developed mathematical solutions for scenarios involving two emitters with up to two excitations.
The findings provide new insights into fundamental concepts of quantum optics and establish ultracold matter waves as valuable tools for studying many-body quantum optics in extended systems. The research was supported by the National Science Foundation with additional backing from Stony Brook’s Center for Distributed Quantum Processing (CDQP).