This PDF file contains the front matter associated with SPIE Proceedings Volume 13120, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

Magnetometers are essential tools for a variety of in situ and remote sensing applications. Earth application comprise GPS-denied navigation, geological surveying and submarine detection, among other applications. In space, these instruments provide valuable data that enhance our understanding of planetary science, Earth science, and heliophysics. Traditional magnetometers, such as Hall sensors, fluxgate devices and optically pumped atomic vapor cells, have seen widespread use. However, recent advancements in material science have led to the increased adoption of quantum center-hosting solid-state magnetometers.

This study demonstrates vector magnetometry based on an optical readout of quantum centers in solid-state systems, capable of measuring both the magnitude and orientation of the ambient magnetic field. The device employs optically detected magnetic resonance (ODMR) of magnetic field-sensitive quantum centers in 6H silicon carbide (SiC). We investigate three operation modes in terms of linearity and isotropy. A fully functional vector magnetometer was realized for all three operational modes, underscoring the potential of 6H SiC as an attractive platform for quantum sensing.

Optically addressable spin defects hosted in two-dimensional van der Waals materials represent a new frontier for quantum technologies, promising to lead to a new class of ultrathin quantum sensors and simulators. Recently, hexagonal boron nitride (hBN) has been shown to host several types of optically addressable spin defects, thus offering a unique opportunity to utilise various spin species in a single material. Here we demonstrate the co-existence of two separate spin species within a single hBN powder sample, namely boron vacancy defects and visible emitter spins. To identify the two spin species, we studied photoluminescence (PL) and optically detected magnetic resonance (ODMR) spectra for the as-received commercially sourced hBN powder and after electron irradiation. Further, we prepared a film of hBN powder on a test magnetic sample (a patterned CoFeB film with in-plane magnetization) and used the hBN spins to spatially map the sample’s stray magnetic field at room temperature.Our results establish hBN as a versatile platform for quantum technologies in a van der Waals host at room temperature.

Directionally unbiased multiports are novel photonic components where each port could equally serve as an input and an output point for light. This new concept of linear-optical devices enables the design of next-generation classical and quantum photonic devices for applications in sensing, metrology, and information processing. Though some unbiased multiports have been realized as collections of free space optics, their implementation in a graph network is impractical due to their sensitivity to misalignment and the strict coherence requirements of their fundamental interference phenomena. Therefore, developing chip-integrated embodiments of interconnected, unbiased multiports will provide an experimental platform for novel quantum photonics devices. This includes enhanced-sensitivity interferometers for navigation, low-power optical modulators, quantum entanglement routing, and discrete-time Hamiltonian simulation. Here we investigate the design of nanoscale, directionally unbiased photonic integrated circuits (PICs), and show how symmetry can be utilized to reach a more optimal design.

This research is devoted to the electronic characteristics of the biconical quantum dot constructed from GaAs, employing the Finite Element Method. The study initiated with the calculation of wave functions and energies for the ground state and the first four excited states. This enabled the discernment of the influence of the quantum dot's geometry on its electronic configuration. Utilizing the derived wave functions and energies for a single electron, the oscillator strengths for various quantum transitions were determined. The absorption spectrum was observed during transitions from the ground to the next four excited states.

The interaction of light with matter can generate different types of scattering that can be applied to quantum optics, photonics and integrated optics appropriately. The generation of certain pulses in certain waveguides can produce certain nonlinear optical pulses with important properties such as low energy and information loss applied, for example, to communication systems and quantum information. The method we describe is based on the generation and propagation of nonlinear optical pulses in multidimensional material structures: waveguides in 1 dimension, planar systems in 2 dimensions and crystalline systems in 3 dimensions. These structures can be appropriately designed to generate nonlinear and quantum optical pulses depending on the crystal structure and electrical susceptibility of the material. These optical pulses can be appropriately characterized whose respective scattering signals can be identified and processed providing an application basis for emerging technologies for transmission and processing systems based on quantum optics and quantum computing.

We derive the theoretical limit of single-photon purity of heralded single-photon sources and accordingly demonstrate a bright, gigahertz-pulsed heralded source with the purity saturating the limit. Based on spontaneous four-wave mixing in a silicon spiral waveguide, this on-chip source is measured to have a coincidence rate exceeding 1.5MHz at a coincidence to accidental (CAR) ratio of 16.77. The single-photon purity, quantified by the auto-correlation function g_h⁽²⁾(0), reaches the theoretical limit with the lowest value of 0.00094 ± 0.00002 obtained at a coincidence rate of 0.8kHz. We attribute our results to effective spectral filtering as well as the coherent pump condition helped by optical injection locking.