Epsilon-Near-Zero Grids for On-chip Quantum Networks

Realization of an on-chip quantum network is a major goal in the field of integrated quantum photonics. A typical network scalable on-chip demands optical integration of single photon sources, optical circuitry and detectors for routing and processing of quantum information. Current solutions either notoriously experience considerable decoherence or suffer from extended footprint dimensions limiting their on-chip scaling. Here we propose and numerically demonstrate a robust on-chip quantum network based on an epsilon-near-zero (ENZ) material, whose dielectric function has the real part close to zero. We show that ENZ materials strongly protect quantum information against decoherence and losses during its propagation in the dense network. As an example, we model a feasible implementation of an ENZ network and demonstrate that quantum information can be reliably sent across a titanium nitride grid with a coherence length of 434 nm, operating at room temperature, which is more than 40 times larger than state-of-the-art plasmonic analogs. Our results facilitate practical realization of large multi-node quantum photonic networks and circuits on-a-chip.Comment: 13 pages, 5 figure

Near-Zero Index Photonic Crystals with Directive Bound States in the Continuum

Near-zero-index platforms arise as a new opportunity for light manipulation with boosting of optical nonlinearities, transmission properties in waveguides and constant phase distribution. In addition, they represent a solution to impedance mismatch faced in photonic circuitry offering several applications in quantum photonics, communication and sensing. However, their realization is limited to availability of materials that could exhibit such low-index. For materials used in the visible and near-infrared wavelengths, the intrinsic losses annihilate most of near-zero index properties. The design of all-dielectric photonic crystals with specific electromagnetic modes overcame the issue of intrinsic losses while showing effective mode index near-zero. Nonetheless, these modes strongly radiate to the surrounding environment, greatly limiting the devices applications. Here, we explore a novel all-dielectric photonic crystal structure that is able to sustain effective near-zero-index modes coupled to directive bound-states in the continuum in order to decrease radiative losses, opening extraordinary opportunities for radiation manipulation in nanophotonic circuits. Moreover, its relatively simple design and phase stability facilitates integration and reproducibility with other photonic components

Retrieval of Effective Parameters of Subwavelength Periodic Photonic Structures

We revisit the standard Nicolson–Ross–Weir method of effective permittivity and permeability restoration of photonic structures for the case of subwavelength metal-dielectric multilayers. We show that the direct application of the standard method yields a false zero-epsilon point and an associated spurious permeability resonance. We show how this artifact can be worked around by the use of the cycle shift operator to the periodic multilayer in question

Photonic Localization of Interface Modes at the Boundary between Metal and Fibonacci Quasi-Periodic Structure

We investigated on the interface modes in a heterostructure consisting of a semi-infinite metallic layer and a semi-infinite Fibonacci quasi-periodic structure. Various properties of the interface modes, such as their spatial localizations, self-similarities, and multifractal properties are studied. The interface modes decay exponentially in different ways and the modes in the lower stable gap possess highest spatial localization. A localization index is introduced to understand the localization properties of the interface modes. We found that the localization index of the interface modes in the upper stable gap will converge to two slightly different constants according to the parity of the Fibonacci generation. In addition, the localization-delocalization transition is also found in the interface modes of the transient gap.Comment: 20 pages, 5figure