Topology-empowered decoherence suppression of strong light-matter interaction in a one-dimensional atomic cavity

The ordered atomic array emerges as a versatile atom-photon interface for exquisite control of light-matter interaction at the nanoscale. In particular, the one-dimensional atom-waveguide system can achieve strong coupling between a single atom and a photon, where two atomic mirrors coupled to waveguide act as a high-finesse cavity. In this work we show that under the strong-coupling regime, the mirror atoms arranged in the form of a Su-Schrieffer-Heeger chain are advantageous in decoherence suppression compared to a nontopological Bragg configuration, manifesting a significant increase in the lifetime of dressed states, substantial narrowing of the spectral linewidth, and order-of-magnitude enhancement of the cooperativity of light-matter interaction. Furthermore, subradiant dressed states with a decay rate smaller than the emission rate of a free-space atom are found in the dissipationless atomic cavity with a few mirror atoms, which cannot be achieved with a Bragg atomic mirror. A theory of the local density of states (LDOS) of the atomic cavity is presented and reveals that the decoherence suppression is directly related to the negative LDOS in a wide frequency range contributed by the bulk modes of the topological atomic cavity. This peculiar feature of the LDOS indicates the destructive quantum interference of photon scattering by the topological edge- and bulk-state channels. Our work demonstrates the great potential of topology in engineering quantum states and enhancing quantum coherence for future applications in quantum computing and quantum information processing.