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Abstract In two-dimensional (2D) NbSe 2 crystal, which lacks inversion symmetry, strong spin-orbit coupling aligns the spins of Cooper pairs to the orbital valleys, forming Ising Cooper pairs (ICPs). The unusual spin texture of ICPs can be further modulated by introducing magnetic exchange. Here, we report unconventional supercurrent phase in van der Waals heterostructure Josephson junctions (JJs) that couples NbSe 2 ICPs across an atomically thin magnetic insulator (MI) Cr 2 Ge 2 Te 6 . By constructing a superconducting quantum interference device (SQUID), we measure the phase of the transferred Cooper pairs in the MI JJ. We demonstrate a doubly degenerate nontrivial JJ phase ( ϕ ), formed by momentum-conserving tunneling of ICPs across magnetic domains in the barrier. The doubly degenerate ground states in MI JJs provide a two-level quantum system that can be utilized as a new dissipationless component for superconducting quantum devices. Our work boosts the study of various superconducting states with spin-orbit coupling, opening up an avenue to designing new superconducting phase-controlled quantum electronic devices. 

Fluorescent portable monitoring systems provide real-time and on-site analysis of a sample solution, avoiding transportation delays and solution degradation. However, some applications, such as environmental monitoring of bodies of water with algae pollution, rely on the temperature control that off-site systems provide for adequate solution results. The goal of this research is the development of a temperature stabilization module for a portable fluorescent sensing platform, which is necessary to prevent inaccurate results. Using a Peltier device-based system, the module heats/cools a solution through digital-to-analog control of the current, using three surface-mounted temperature modules attached to a copper cuvette holder, which is directly attached to the Peltier device. This system utilizes an in-house algorithm for control, which effectively minimizes temperature overshooting when a change is enacted. Finally, with the use of a sample fluorescent dye, Rhodamine B, the system's controllability is highlighted through the monitoring of Rhodamine B's fluorescence emission decrease as the solution temperature increases. 

The QCD axion is a particle postulated to exist since the 1970s to explain the strong-CP problem in particle physics. It could also account for all of the observed dark matter in the Universe. The axion resonant interaction detection experiment (ARIADNE) intends to detect the QCD axion by sensing the fictitious ‘magnetic field’ created by its coupling to spin. Short-range axion-mediated interactions can occur between a sample of laser-polarized³He nuclear spins and an unpolarized source-mass sprocket. The experiment must be sensitive to magnetic fields below the 10⁻¹⁹T level to achieve its design sensitivity, necessitating tight control of the experiment’s magnetic environment. We describe a method for controlling three aspects of that environment which would otherwise limit the experimental sensitivity. Firstly, a system of superconducting magnetic shielding is described to screen ordinary magnetic noise from the sample volume at the 10⁸level, which should be sufficient to reduce the contribution of Johnson noise in the sprocket-shaped source mass, expected to be at the 10⁻¹²T$/\sqrt{\mathrm{H}\mathrm{z}}$level, to below the threshold for signal detection. Secondly, a method for reducing magnetic field gradients within the sample up to 10²times is described, using a simple and cost-effective design geometry. Thirdly, a novel coil design is introduced which allows the generation of fields similar to those produced by Helmholtz coils in regions directly abutting superconducting boundaries. This method allows the nuclear Larmor frequency of the sample to be tuned to match the axion field modulation frequency set by the sprocket rotation. Finally, we experimentally investigate the magnetic shielding factor of sputtered thin-film superconducting niobium on quartz substrates for various geometries and film thicknesses relevant for the ARIADNE axion experiment using SQUID magnetometry. The methods may be generally useful for magnetic field control near superconducting boundaries in other experiments where similar considerations apply.

 

Fluorescence dyes are widely used in biomolecule detection/quantification, flow tracing reference for gases and liquids, pathogen detection, and other life science applications. However, fluorescence emission efficiency of the dyes is easily affected by several parameters, such as polarity, pH, and temperature. Therefore, it is essential to monitor and control these parameters for reliable and accurate measurements. We propose a 3D-printed copper cuvette holder (i.materialise, Belgium) joined with a Peltier-based temperature controller platform for stable reading of fluorescence emission from the dye. For demonstration of temperature effects on fluorescence efficiency, rhodamine B, which is one of the widely used fluorescence standards and probes in bioscience, was used. For excitation, 530 nm wavelength lighting was utilized for stimulating the rhodamine B. A Peltier device was controlled with different levels of direct current (DC) to demonstrate the temperature controlling capability of the device and fluorescence efficiency of the rhodamine B was tested with a varying temperature level: 20 ºC to 80 ºC. For our device, the temperature will be monitored by temperature ICs that are attached at three different points of the copper body for uniform temperature heating of the solution in a cuvette. We have monitored the temperature distribution of the copper holder with an external temperature monitor, the DT304, and determined that the temperature is maintained to with a 5 ºC. We plan to monitor the solution temperature directly with the use of an infrared temperature sensor positioned down at the opening of the cuvette. The ambient temperature and the temperature of the opposite junction of the Peltier device will be monitored through the use of two thermocouples. An analysis of several different temperature components of the device allow for a better interpretation of what is happening in the system. Moreover, the implementation of a water-cooling apparatus will allow for a way to quickly decrease the temperature of the cuvette when desirable. These features allow for the sample to be monitored efficiently, allowing for proper stabilization techniques and the ability to fluctuate the temperature when required of an application. In summary, we have developed an 3D-printed copper cuvette holder with a Peltier-based temperature controller platform for stable reading of fluorescence emission from the dye or fluorophore solution. Our compact temperature controller system provides viable option for any fluorometers to easily apply it for temperature stabilization during the fluorescence dye testing. 

The Axion Resonant InterAction Detection Experiment (ARIADNE) is a collaborative effort to search for the QCD axion using nuclear magnetic resonance (NMR), where the axion acts as a mediator of spin-dependent forces between an unpolarized tungsten source mass and a sample of polarized helium-3 gas. Since the experiment involves precision measurement of a small magnetization, it relies on limiting ordinary magnetic noise with superconducting magnetic shielding. In addition to the shielding, proper characterization of the noise level from other sources is crucial.We investigate one such noise source in detail: the magnetic noise due to impurities and Johnson noise in the tungsten source mass. 

Our understanding of the processes that control the burden and budget of tropospheric ozone has changed dramatically over the last 60 years. Models are the key tools used to understand these changes, and these underscore that there are many processes important in controlling the tropospheric ozone budget. In this critical review, we assess our evolving understanding of these processes, both physical and chemical. We review model simulations from the International Global Atmospheric Chemistry Atmospheric Chemistry and Climate Model Intercomparison Project and Chemistry Climate Modelling Initiative to assess the changes in the tropospheric ozone burden and its budget from 1850 to 2010. Analysis of these data indicates that there has been significant growth in the ozone burden from 1850 to 2000 (approximately 43 ± 9%) but smaller growth between 1960 and 2000 (approximately 16 ± 10%) and that the models simulate burdens of ozone well within recent satellite estimates. The Chemistry Climate Modelling Initiative model ozone budgets indicate that the net chemical production of ozone in the troposphere plateaued in the 1990s and has not changed since then inspite of increases in the burden. There has been a shift in net ozone production in the troposphere being greatest in the northern mid and high latitudes to the northern tropics, driven by the regional evolution of precursor emissions. An analysis of the evolution of tropospheric ozone through the 21st century, as simulated by Climate Model Intercomparison Project Phase 5 models, reveals a large source of uncertainty associated with models themselves (i.e., in the way that they simulate the chemical and physical processes that control tropospheric ozone). This structural uncertainty is greatest in the near term (two to three decades), but emissions scenarios dominate uncertainty in the longer term (2050–2100) evolution of tropospheric ozone. This intrinsic model uncertainty prevents robust predictions of near-term changes in the tropospheric ozone burden, and we review how progress can be made to reduce this limitation.