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Applied Physics Letters

Ideal long-range quantum-resource generator in zero-index photonic crystal waveguide

Yalong Qin, Jicheng Wang, Yun Zhu, Moran Li, Sergei A. Khakhomov, Yueke Wang, Zheng-Da Hu

Published Apr 20, 2026• 0 citations
Publisher

Abstract

Mitigating quantum decoherence and enhancing long-range entanglement are critical to the advancement of quantum information applications. We propose a photonic crystal-air-photonic crystal sandwich-structured waveguide system, which exhibits zero index by utilizing the accidental degeneracy between the waveguide mode and two bound modes. We evaluate transient and steady-state quantum information (including entanglement and coherence), demonstrating the robust generation of quantum resources over arbitrarily long distances. To the best of our knowledge, this work represents the first realization of an ideal long-range quantum-resource generator based on a zero-index waveguide.

DOI
10.1063/5.0321451

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This Thesis is focused on the study of quantum electrodynamics in photonic crystal waveguides. We investigate the interplay between a single quantum dot and the fundamental mode of the photonic crystal waveguide. We demonstrate experimental coupling eciencies for the spontaneous emission into the mode exceeding 98% for emitters spectrally close to the band-edge of the waveguide mode. In addition we illustrate the broadband nature of the underlying eects, by obtaining coupling eciencies above 90% for quantum dots detuned from the band edge by as far as 20nm. These values are in good agreement with numerical simulations. Such a high coupling eciency implies that the system can be considered an articial 1D-atom, and we theoretically show that this system can generate strong photon-photon interaction, which is an essential functionality for deterministic optical quantum information processing. We present the progress towards the experimental demonstration of such a strong photon-photon nonlinearity. We present the rst signatures of resonant transmission in photonic crystal waveguides and discuss some of the encountered diculties and future directions of the experiments. In the nal part of this Thesis we discuss a novel type of photonic crystal waveguide and show its applications for on-chip quantum information processing. This structure was designed for the ecient mapping of two orthogonal circular dipole transitions to dierent propagation paths of the emitted photon, i.e. exhibits chiral quantum-dot-waveguide coupling. Such a structure is ideally suited for a number of applications in quantum information processing and among others we propose an on-chip spin-photon interface, a single photon transistor, and a deterministic cNOT gate.
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We demonstrate degenerate, correlated photon-pair generation via slow-light-enhanced spontaneous four-wave mixing in a 96 μm long silicon photonic crystal waveguide. Our device represents a more than 50 times smaller footprint than silicon nanowires. We have achieved a coincidence-to-accidental ratio as high as 47 at a photon generation rate of 0.001 pairs per pulse and 14 at a photon generation rate of 0.023 pairs per pulse, which are both higher than the useful level of 10. This demonstration provides a path to generate indistinguishable photons in an ultracompact platform for future quantum photonic technologies.