What it is
Rydberg atoms, atoms with one electron excited to a very high orbit, underpin much recent work in quantum computation, simulation, sensing and metrology, and they also make light interact strongly with light: coupled to photons travelling through an atomic cloud, they form collective excitations called Rydberg polaritons that interact strongly with each other. The authors experimentally explore the interaction between a Rydberg polariton in an atomic ensemble and a single, adjacent Rydberg atom. They find three regimes of quantum dynamics, set apart by their transmission signatures: polariton blockade, coherent exchange and probabilistic hopping, with the passage from blockade to coherent exchange going through an exceptional point, a degeneracy of a lossy (non-Hermitian) system where two energy eigenvalues coalesce. The regimes are read from the transmission data; the exceptional point is identified from eigenvalues the authors calculate at the measured boundary between them. They investigate using such interactions for fast, non-destructive detection of Rydberg atoms, and present proof-of-principle demonstrations of their potential application in nonlinear photonic networks.
Why it matters
This interaction reads a Rydberg atom's state without destroying it, from a detector a short distance away. Until now, the preprint says, that was only possible with the atom inside the detection ensemble. In the preprint the atom sits 20 micrometres from its detector, single-shot preparation and detection together reach 47% fidelity within 30 microseconds, and repeating the readout 20 times on the same ensemble raises it to 79%.
Underlined numbers link to their source. Every metric and quoted figure is listed under Sources and data below.
Filed underQuantum optics and atomic interactions, Strong Light-Matter Interactions, Cold Atom Physics and Bose-Einstein Condensates
