Multi-Level Variational Spectroscopy using a Programmable Quantum Simulator

Energy spectroscopy is a powerful tool with diverse applications across various disciplines. The advent of programmable digital quantum simulators opens new possibilities for conducting spectroscopy on various models using a single device. Variational quantum-classical algorithms have emerged as a promising approach for achieving such tasks on near-term quantum simulators, despite facing significant quantum and classical resource overheads. Here, we experimentally demonstrate multi-level variational spectroscopy for fundamental many-body Hamiltonians using a superconducting programmable digital quantum simulator. By exploiting symmetries, we effectively reduce circuit depth and optimization parameters allowing us to go beyond the ground state. Combined with the subspace search method, we achieve full spectroscopy for a 4-qubit Heisenberg spin chain, yielding an average deviation of 0.13 between experimental and theoretical energies, assuming unity coupling strength. Our method, when extended to 8-qubit Heisenberg and transverse-field Ising Hamiltonians, successfully determines the three lowest energy levels. In achieving the above, we introduce a circuit-agnostic waveform compilation method that enhances the robustness of our simulator against signal crosstalk. Our study highlights symmetry-assisted resource efficiency in variational quantum algorithms and lays the foundation for practical spectroscopy on near-term quantum simulators, with potential applications in quantum chemistry and condensed matter physics

An Improvement Approach for Wide-Angle Impedance Matching Using ELC Metasurface Slabs for SIW Slot Array Antennas

The effects of mutual coupling in beam scanning arrays increase degradation in gain as the beam is scanned off the broadside. A simple and effective approach for a deployed SIW slot array antenna through the use of artificially structured materials is proposed to improve its performance of wide-angle scanning in the E-plane. Metasurface slabs of one-tenth wavelength electric-inductive-capacitive (ELC) resonators are vertically placed halfway between the adjacent waveguides without changing the antenna structure to realize wide-angle impedance matching (WAIM). The ELC metasurface is designed to operate at a linear region rather than at a resonance region to use its transmission property for greatly weakening mutual couplings. Inserting metasurface slabs between two adjacent waveguides to reduce the mutual coupling can achieve impedance matching at large scan angles. A 10 × 10 SIW slot array operating at X-band is modelled and simulated to study how the vertically placed ELC metasurface slabs over the antenna affect the array’s beam scanning performance. The simulated results show that the scan range of the antenna is extended from −50° to 50° to −70° to 70° under the criteria that radiating efficiency is greater than 80%

Simulation and Analysis of the Complex Dynamic Behavior of Supply Chain Inventory System from Different Decision Perspectives

Based on the local decision perspective and the global decision perspective, considering the limitation of supply capacity and prohibiting returns, the system dynamics method is used to establish a nonlinear supply chain system model. We use the Z-transform theory to transform the dynamic transfer equation into a block diagram, build a supply chain system simulation model, and use it to conduct simulation experiments. The Wolf reconstruction method is used to calculate the largest Lyapunov exponent (LLE) value of each node or combined system to judge the stability of the system. Based on different decision-making perspectives, under different combinations of safety stock factors and demand scenarios, the adjustment coefficients’ decision-making schemes that keep each node in a stable state are obtained. Then, we comparatively analyze the inventory changes of each node and combined system in a stable state under different decision-making schemes

Novel room-temperature perylene liquid crystals: synthesis of 1,7-dibrominated cholesterol–perylene bisimides with different ester-bridging chains and their mesomorphic properties

<p>Three novel 1,7-dibrominated cholesterol–perylene liquid crystals <b>6a, 6b</b> and <b>6c</b> with different ester-bridging chains were designed and synthesised in yields of 30–40%. Their structures were characterised by FT-IR, ¹H NMR and HR-MS spectra. Their mesomorphic behaviours were studied by differential scanning calorimetry (DSC), polarising optical microscopy (POM) and X-ray diffraction (XRD). Compounds <b>6a, 6b</b> and <b>6c</b> exhibit hexagonal columnar liquid crystalline phase at room temperature. Their mesomorphic temperature ranges are as wide as 140–162°C. Their fluorescence spectra suggested that they possess good fluorescence properties in solution. The soft ester-bridging chains are more favourable for room-temperature mesophase and high fluorescence than the rigid ester-bridging chain.</p

Design of Multilayer Dielectric Cover to Enhance Gain and Efficiency of Slot Arrays

An effective design procedure, based on the Elliot synthesis method, is proposed to investigate the properties of waveguide slot arrays with multilayer dielectric cover. Then, the features of the designed arrays are analyzed by means of a FEM commercial software, namely, Ansys HFSS 13. We show how a proper choice of the dielectric cover configuration allows increasing the array gain and aperture efficiency, while taking advantage of the properties of the radome structure, in terms of insulation, protection, and pressurization of the radiating waveguides. Therefore, a significant outcome of the optimal choice of the multilayer dielectric cover is the reduction of the number of slots with respect to an array radiating into free space with the same gain and efficiency, with a consequent reduction of the production cost

Design of Multilayer Dielectric Cover to Enhance Gain and Efficiency of Slot Arrays

An effective design procedure, based on the Elliot synthesis method, is proposed to investigate the properties of waveguide slot arrays with multilayer dielectric cover. Then, the features of the designed arrays are analyzed by means of a FEM commercial software, namely, Ansys HFSS 13. We show how a proper choice of the dielectric cover configuration allows increasing the array gain and aperture efficiency, while taking advantage of the properties of the radome structure, in terms of insulation, protection, and pressurization of the radiating waveguides. Therefore, a significant outcome of the optimal choice of the multilayer dielectric cover is the reduction of the number of slots with respect to an array radiating into free space with the same gain and efficiency, with a consequent reduction of the production cost