A topological quantum optics interface (1711.00478v1)

Abstract: The application of topology in optics has led to a new paradigm in developing photonic devices with robust properties against disorder. Although significant progress on topological phenomena has been achieved in the classical domain, the realization of strong light-matter coupling in the quantum domain remains unexplored. We demonstrate a strong interface between single quantum emitters and topological photonic states. Our approach creates robust counter-propagating edge states at the boundary of two distinct topological photonic crystals. We demonstrate the chiral emission of a quantum emitter into these modes and establish their robustness against sharp bends. This approach may enable the development of quantum optics devices with built-in protection, with potential applications in quantum simulation and sensing.

• The paper demonstrates robust chiral emission by coupling single quantum emitters to topologically protected edge states.
• It employs GaAs honeycomb photonic crystals to induce band inversions and achieve a 68% coupling efficiency.
• Results confirm that photons propagate without back-reflection through a 60° bent waveguide, showcasing topological protection.

Analysis of Topological Quantum Optics Interface

The paper "A topological quantum optics interface" presents an intersection of the fields of topology and quantum optics, exploring the potential for robust photonic devices driven by quantum principles. This work focuses on advancing the integration of quantum emitters with topological photonic structures to realize strong light-matter coupling, a domain that has been previously underexplored experimentally.

Summary of Key Contributions

This paper demonstrates the interaction between single quantum emitters and topologically protected photonic states. Central to this research is the creation of robust counter-propagating edge states at the interface between two distinct topological photonic crystals. The authors showcase a chiral emission of quantum emitters into these modes and establish their robustness against distortions such as sharp bends.

Key experiments involve the use of a GaAs membrane deformed into a honeycomb-like photonic crystal structure, which forms topologically different regions. By perturbing these regions, the researchers opened bandgaps that exhibit band inversions. These anomalies support helical edge modes marked by opposite circular polarizations, facilitating photon propagation without back-reflection even in the presence of structural bends.

Numerical Findings and Experimental Results

Significant numerical results include a robust coupling efficiency of 68%, achieved by confining electromagnetic modes. Furthermore, an anti-bunching measurement corroborates the presence of single photons emitted along the waveguide, confirming the chiral nature of photon emission wherein different dipole spins couple to opposite helical states.

The researchers applied a 60-degree bend to the waveguide, observing that the emitted photons maintained their directional propagation, signifying robustness in two dimensions—an insightful demonstration of topological protection. The preservation of signal integrity despite the structural bend is a noteworthy finding, illustrating promise for future robust photonic circuits.

Implications and Future Directions

The demonstrated strong coupling between quantum emitters and topologically robust states bears potential for advancing quantum optics, particularly in the context of topologically protected quantum simulations and sensing technologies. This coupling feature provides a platform for location-independent, photon-mediated interactions and suggests possibilities for scalable systems of large-scale super-radiant states and spin-squeezing networks.

The methodologies outlined have broader implications in exploring many-body quantum physics on topological edges and could pave the way for generating fractional quantum Hall states of light. Looking forward, further exploration could involve expanding these experiments with diverse photonic materials and structures, probing new regimes of light-matter interaction with topological protection.

In summary, this paper offers a substantial contribution to the field by bridging the gap between quantum optics and topology, opening avenues for robust quantum photonic devices and advancing theoretical frameworks of topological states in the quantum regime.