Directional and correlated optical emission from a waveguide-engineered molecule with local control

Quantum Physics [Submitted on 7 Apr 2026] Directional and correlated optical emission from a waveguide-engineered molecule with local control Clara Henke, Thomas Wilkens Sandø, Vasiliki Angelopoulou, Lena Maria Hansen, Alexey Tiranov, Oliver August Dall'Alba Sandberg, Zhe Liu, Leonardo Midolo, Nikolai Bart, Arne Ludwig, Anders Søndberg Sørensen, Peter Lodahl, Cornelis Jacobus van Diepen Radiative coupling between quantum emitters leads to a range of spectacular emission phenomena. Dicke studied the foundations of collectively enhanced and suppressed decay, commonly referred to as super- and subradiance. Collective effects can further result in directionality of the emission, thus offering a complimentary implementation of chiral quantum optics. Waveguide quantum electrodynamics (QED) allows coupling between spatially separated emitters, enabling selective driving. In this work, we control the emission direction for a pair of quantum dots embedded in a bidirectional photonic crystal waveguide offering independent electrical tuning. Notably the emitters are 13 \micro m apart, which corresponds to 26 effective wavelengths, but are nevertheless radiatively coupled. The directionality arises from a dispersive dipole-dipole interaction, which shifts the energy of the collective states, so that the emitter pair effectively forms an artificial molecule. We show that the emission direction can be switched from left- to rightwards by manipulating the relative driving phase while collectively exciting the emitters. In addition, we observe directional photon statistics under continuous driving, with, for example, single photons detected on one output port, and photon pairs on the other. With pulsed excitation, both emitters are fully inverted and correlated photon pairs are observed in time-resolved intensity correlation measurements. This work demonstrates a novel implementation of chiral quantum optics using quantum dots coupled via a non-chiral waveguide, and reports key steps for scaling up as a multi-emitter waveguide QED platform. Comments: 22 pages, 18 figures Subjects: Quantum Physics (quant-ph); Optics (physics.optics) Cite as: arXiv:2604.06410 [quant-ph]   (or arXiv:2604.06410v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2604.06410 Focus to learn more Submission history From: Cornelis Jacobus Van Diepen [view email] [v1] Tue, 7 Apr 2026 19:46:52 UTC (4,903 KB) Access Paper: view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-04 Change to browse by: physics physics.optics References & Citations INSPIRE HEP NASA ADS Google Scholar Semantic Scholar Export BibTeX Citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Demos Related Papers About arXivLabs Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)