A superconducting qubit in a waveguide behaves as a pointlike nonlinear element. If irradiated with nearly resonant microwave pulses, the qubit undergoes quantum evolution and generates coherent fields at sideband fre...
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A superconducting qubit in a waveguide behaves as a pointlike nonlinear element. If irradiated with nearly resonant microwave pulses, the qubit undergoes quantum evolution and generates coherent fields at sideband frequencies due to elastic scattering. This effect is called quantum wave mixing (QWM), and the number of emerged side components depends on the number of interacting photons. By driving a superconducting qubit with short pulses with alternating carrier frequencies, we control the maximal number of photons simultaneously interacting with a two-level system by varying the number and duration of applied pulses. Increasing the number of pulses results in consecutive growth of the order of nonlinearity, which manifests in additional coherent side peaks appearing in the spectrum of scattered radiation while the whole spectrum maintains its asymmetry.
In this paper, a compact and single-mode X-band dielectric-loaded matching section with constant tilt angle, blended edges, and two discontinuities at both ends is analyzed by the transmission line model. This matchin...
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In this paper, a compact and single-mode X-band dielectric-loaded matching section with constant tilt angle, blended edges, and two discontinuities at both ends is analyzed by the transmission line model. This matching section is designed as a high-power injection coupler to a dielectric-loaded accelerating structure (DLA). Although the transmission line model is a powerful tool for single-mode structures, because of radial inhomogeneity and lack of single value for characteristic impedance in dielectric-loaded structures, this method is not applicable in non-uniform dielectric-loaded structures. To solve this problem, it is shown that a dielectric-loaded waveguide (DLW) can be modeled by a dielectric-filled waveguide (DFW) with the same parameters of the phase constant, power flow, and dielectric loss. The characteristic impedance of a dielectric-filled waveguide can be determined by three structural parameters of the real and imaginary parts of the dielectric material and inner radius. These structural parameters can be found by solving a non-linear equation system made by equality of the parameters of the dielectric-loaded and dielectric-filled waveguides. To analyze the matching section, it is stratified to low thickness and uniform DLWs in the propagation direction and every segment is substituted by its equal DFW model. However, because of sharp variation in dielectric region at two ends of the flared section, solving the non-linear equation system is difficult at these points due to the lack of a proper initial point for the answer. Therefore, two virtual sections are added at the discontinuities to smoothen the variation of the dielectric region. Then, the total transmission matrix and scattering matrix parameters can be obtained without considering the added virtual sections. Moreover, the matching section is simulated by a full-wave electromagnetic software and the results of the scattering matrix parameters are compared with the ones of the proposed metho
Photonic moire lattices offer an attractive platform for manipulating the flow and confinement of light from remarkably simple device geometries. This emerging field draws inspiration from the rapid research progress ...
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Photonic moire lattices offer an attractive platform for manipulating the flow and confinement of light from remarkably simple device geometries. This emerging field draws inspiration from the rapid research progress observed in twisted bilayer van der Waals materials or "twistronics," instead of applying moire physics to photon propagation in wavelength-scale optical media. However, to date, only a limited number of experimental studies have been performed in this area, and there is strong interest in understanding how moire effects can be tailored in compact and scalable optical technologies such as an integrated photonics platform. In this work, we map the moireeffects of one-dimensional (1D) photonic moire lattices composed of widthmodulated silicon nanowires, including the construction of a 1D experiment analogous to the twisting of a two-dimensional (2D) lattice. Although the twist angle Delta theta and/or lattice mismatch Delta Lambda are the sole defining parameters for infinite moire crystals, we demonstrate how the crystal size, symmetry, and moire fringe phase Delta phi also serve as important degrees of freedom. Through tailoring these parameters, we map a wide range of behaviors including the formation of moirephotonic crystal cavities, the onset of miniband formation and operation as a coupled resonator optical waveguide (CROW), widely tunable Q-factors and group velocities, suppression of grating sidebands, and persistent vs extinguishable tunneling. These results provide insight into the moire physics of 1D optical systems and highlight various operating regimes relevant to the design of finite photonic moire lattices and devices.
So far, acoustic black holes have been investigated mainly for flexural waves in thin plates for which the required linear or higher order reduction in wave velocity with distance can be easily achieved by changing th...
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For terahertz spectroscopy on single crystals, the wavelength lambda often is comparable to the size of the studied samples, emphasizing diffraction effects. Using a continuous-wave terahertz spectrometer in transmiss...
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For terahertz spectroscopy on single crystals, the wavelength lambda often is comparable to the size of the studied samples, emphasizing diffraction effects. Using a continuous-wave terahertz spectrometer in transmission geometry, we address the effect of the sample size on the achievable accuracy of the optical properties, focusing in particular on the phase data. We employ alpha-lactose monohydrate as a paradigmatic example and compare data that were measured using apertures with diameters D in the range from 10 to 0.2 mm. For small D, strong diffraction typically invalidates a quantitative analysis of the transmitted amplitude at low frequencies. The phase data, however, can be evaluated to lower frequency and show a more systematic dependence on D. For a quantitative analysis, we employ a waveguide picture for the description of small apertures with a cylindrical bore. For D as small as 0.2 mm, corresponding to 1/D = 50 cm(-1), a circular waveguide does not support propagating waves below its cut-off frequency 1/lambda(c) = omega(c)/2 pi c approximate to 29 cm(-1). Experimentally, we confirm this cut-off for cylindrical apertures with a thickness d(ap) = 1 mm. Close to omega(c), the measured phase velocity is an order of magnitude larger than c, the speed of light in vacuum. The cut-off is washed out if a sample is mounted on a thin aperture with a conical bore. In this case, the phase data of alpha-lactose monohydrate for D = 0.2 mm can quantitatively be described down to about 10 cm(-1) if the waveguide-like properties of the aperture are taken into account in the analysis.
Unlike phononic crystals or systems designed by topology optimization, waveguides designed by shape optimization do not have voids or internal defects, making the fabrication process more suitable for additive manufac...
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Unlike phononic crystals or systems designed by topology optimization, waveguides designed by shape optimization do not have voids or internal defects, making the fabrication process more suitable for additive manufacturing. By designing a Y-junction waveguide through shape optimization, an ultrasonic wave can be controlled so that it propagates to a predetermined location just by adjusting its frequency. These demultiplexed ultrasonic waves can be used to transport signals or stimulate nearby materials. As an example, the ultrasonic wave is converted to heat at different locations, which can be applied to mechanisms that can take advantage of heating. First, shape optimization is performed on a cylindrical structure to selectively propagate ultrasonic waves of a particular frequency while attenuating others, which is analyzed through a finite element model. The numerical study results are compared with experimental measurements from samples fabricated through additive manufacturing methods. After verifying the concept, the Y-junction waveguide is fabricated to demultiplex the wave and selectively heat different locations. The results show that the method of combining shape optimization with additive manufacturing is exceptionally simple and capable of demultiplexing ultrasonic waves, which can replace complex electrical components with single-material waveguides.
We demonstrate the presence of a mode originates from the guided mode within a metasurface waveguide, albeit possessing quasi-trapped attributes. This finding enables us to independently manipulate multiple nonlocal m...
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We develop models of the formation of additive sea noise and surface reverberation at the output of a phased vertical antenna placed in a plane-layered waveguide with a two-dimensional variable-depth bottom. The study...
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We develop models of the formation of additive sea noise and surface reverberation at the output of a phased vertical antenna placed in a plane-layered waveguide with a two-dimensional variable-depth bottom. The study is performed within the framework of geometrical acoustics. The noise calculations are performed for various types of refractive waveguides under conditions of coastal waters. The results of the studies allow one to conclude that the maximum contribution is ensured by the shallow-water areas concentrated near the radiating and receiving antennas. The directions of the main lobes of the antenna patterns also play a significant role during the noise formation.
Atomic-level imperfections play an increasingly critical role in nanophotonic device performance. However, it remains challenging to accurately characterize the sidewall roughness with sub-nanometer resolution and dir...
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Atomic-level imperfections play an increasingly critical role in nanophotonic device performance. However, it remains challenging to accurately characterize the sidewall roughness with sub-nanometer resolution and directly correlate this roughness with device performance. A method that allows to measure the sidewall roughness of waveguides made of any material (including dielectrics) using the high resolution of atomic force microscopy is developed. This method is illustrated by measuring state-of-the-art photonic devices made of silicon nitride. The roughness of devices fabricated using both deep ultraviolet (DUV) photo-lithography and electron-beam lithography for two different etch processes is compared. To correlate roughness with device performance, a new Payne-Lacey Bending model is described, which adds a correction factor to the widely used Payne-Lacey model so that losses in resonators and waveguides with bends can be accurately predicted given the sidewall roughness, waveguide width and bending radii. Having a better way to measure roughness and use it to predict device performance can allow researchers and engineers to optimize fabrication for state-of-the-art photonics using many materials.
We propose a complete architecture for deterministic generation of entangled multiphoton states. Our approach utilizes periodic driving of a quantum-dot emitter and an efficient light-matter interface enabled by a pho...
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We propose a complete architecture for deterministic generation of entangled multiphoton states. Our approach utilizes periodic driving of a quantum-dot emitter and an efficient light-matter interface enabled by a photonic crystal waveguide. We assess the quality of the photonic states produced from a real system by including all intrinsic experimental imperfections. Importantly, the protocol is robust against the nuclear spin bath dynamics due to a naturally built-in refocusing method reminiscent to spin echo. We demonstrate the feasibility of producing Greenberger-Horne-Zeilinger and one-dimensional cluster states with fidelities and generation rates exceeding those achieved with conventional “fusion” methods in current state-of-the-art experiments. The proposed hardware constitutes a scalable and resource-efficient approach towards implementation of measurement-based quantum computing and quantum communication.
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