Review of Scientific Instruments最新文献

A scalable control architecture for superconducting quantum processors is essential as the number of qubits increases and coherent multi-qubit operations span beyond the capacity of a single control module. The Quantum Instrumentation Control Kit (QICK), built on AMD RFSoC platforms, offers a flexible open-source framework for pulse-level qubit control but lacks native support for multi-board synchronization, limiting its applicability to mid- and large-scale quantum devices. To overcome this limitation, we introduce Manarat, a scalable multi-board control platform based on QICK that incorporates hardware, firmware, and software enhancements to enable sub-100 ps timing alignment across multiple AMD ZCU216 RFSoC boards. Our system integrates a low-jitter clock distribution network, modifications to the tProcessor, and a synchronization scheme to ensure deterministic alignment of program execution across boards. It also includes a custom analog front-end for flux control that combines high-speed RF signals with software-programmable DC biasing voltages generated by a low-noise, high-precision DAC. These capabilities are complemented by a software stack capable of orchestrating synchronized multi-board experiments and fully integrated with the open-source Qibo framework for quantum device calibration and algorithm execution. We validate Manarat on a 10-qubit superconducting processor controlled by two RFSoC boards, demonstrating reliable execution of synchronized control sequences for cross-board CZ gate calibration. These results confirm that sub-nanosecond synchronization and coherent control are achievable across multiple RFSoC boards, enabling scalable operation of superconducting quantum computers.

A new L-shaped molecular beam Fourier transform microwave spectrometer (L-FTMW) has been developed at Tennessee Tech University to perform both cavity and chirped-pulse rotational spectroscopy within a single platform. The instrument features an L-shaped high-vacuum chamber comprised of stainless-steel and polycarbonate sections, allowing orthogonal operation of Fabry-Perot cavity and chirped-pulse configurations without mechanical reconfiguration. This paper focuses on the design, operation, and performance of the 8-18 GHz Fabry-Perot cavity subsystem within the L-FTMW spectrometer. The cavity is formed by two 7.5-inch-diameter aluminum mirrors with 30 cm radii of curvature, arranged near-confocally and coupled to a near-coaxial pulsed molecular beam. A custom Python-based interface enables automated high-resolution mapping of cavity resonances and broadband data acquisition with minimal user intervention. The system routinely achieves 2 kHz frequency resolution, enabling precise measurement of hyperfine spectral features. Performance was validated through measurements of benchmark systems, including OCS isotopologues and their weakly bound van der Waals complexes. The 17O13CS isotopologue (natural abundance = 0.000 397 2%, corresponding to ∼40 ppb in a 1% OCS/argon mixture) was detected within 5 min of signal averaging at natural abundance with argon as the carrier gas. The simple mechanical design and open-source control software make the L-FTMW spectrometer a versatile and accessible platform for high-resolution rotational spectroscopy and future investigations of reaction dynamics and kinetics.

Reducing sample volumes for electron paramagnetic resonance (EPR) spectroscopy applications places increasing demands on hardware design to preserve or enhance EPR signal intensity. This work presents the design, fabrication, and testing of dielectric resonators and multi-channel aqueous sample cells for applications in X-band (nominally 9.5 GHz) EPR. Our aim was to maximize the EPR signal intensity for sample sizes of 3-4 μl and 200 nl. These advances are summarized as follows: single-crystal sapphire and rutile dielectric resonators with very low loss tangent and high resonator efficiency; minimum dielectric resonator coupling to radiation shield to reduce ohmic losses; 3D-printed aqueous sample cells with thin multi-channel construction to minimize radio frequency dissipation in the sample; and a Gordon coupler for maximum coupling range and minimum stored energy to eliminate frequency shifts during tuning. Sample tube cross sections were designed by leveraging insights gained from analytic theory to inform finite-element modeling of electromagnetic fields. Experimental comparisons of multi-channel sample cells using a sapphire resonator exhibited a 2.2-fold increase in EPR signal intensity compared with a standard capillary at 3-4 μl, while simulations predict an additional 23% improvement with further 3D printing advances. For samples at 200 nl, a rutile dielectric resonator with a multi-channel sample cell was simulated to improve EPR sensitivity by a 2.7-fold increase compared with a capillary at the same volume.

This paper presents a systematical transmission coil design method for a dual-load wireless power transfer (WPT) system based on a rectangular coil structure. The main design steps are as follows: (1) The system circuit model and the mathematical dimension model of the coupling coils are established to determine the inductance range of the receiving coil and the transmitting coil. (2) Three coil inductance calculation methods such as the finite element method (FEM), greenhouse formula method and backpropagation neural network (BPNN) are analyzed and compared. The FEM and BPNN hybrid method are finally selected for determining the relationship between rectangular coil size, coil turns, and inductance, which is a more efficient modeling scheme and can achieve enough modeling accuracy. (3) Based on calculated inductance characteristics, the length and width of the rectangular coil can be obtained with a geometric mapping scheme, and moreover, the coil size with optimal costs can be estimated. Detailed theoretical analyses are provided. Finally, simulations and experiments are performed for verification.

The number of deaths due to cardiovascular diseases has been steadily increasing, with the majority occurring in underdeveloped regions. Doctors in less developed regions often have limited clinical experience to diagnose these diseases by listening heart sounds, whereas artificial intelligence can serve as a valuable tool to assist them in conducting auxiliary diagnoses. However, small samples and strong noise reduce the diagnosis accuracy. Therefore, in this paper, a novel method is put forward for heart sound classification, which integrates sample augmentation and injected noise dual attention networks (INDANet). First of all, the heart sounds are preprocessed through a Butterworth filter to eliminate noise outside the cardiac frequency range. Then, a sample augmentation is utilized to increase the size of sample set. In addition, a suitable dose of Gaussian noise is injected to improve the robustness and generalization of INDANet with channel and spatial attention mechanism. Experiments on two datasets demonstrate that the proposed method achieves superior performance in heart sound classification compared to the other six advanced models. The accuracy in the two datasets achieves as high as 99.85% and 98.07%, respectively.

Since their discovery over 90 years ago, neutrons have become one of the premier tools in the study of the structure and dynamics of matter and materials. The main nuclear processes to generate a large number of free neutrons are fusion, fission, and spallation, which have been well established for using neutrons in broad areas of physics, material science, engineering, life sciences, and elsewhere. The vast majority of experiments that use neutrons as a probe require a directional, well-collimated beam of neutrons. Over the years, methods have been developed to deliver such neutron beams sufficiently, but it is still much desired to improve the efficiency of neutron sources. With the advent of high-powered lasers, laser-driven neutron sources suggest an attractive possibility. Laser photons can be converted to neutrons by accelerating particles (electrons, protons, and deuterons) and then either utilize hard x rays from, for example, electron acceleration to create photoneutrons or nuclear reactions, such as deuteron break-up. The maturity of such processes in recent years might have reached a state where such neutron sources are becoming useful and beneficial to the neutron community. In the present report, the current state-of-the-art of a laser-driven neutron source and its future development for neutron applications are presented, and existing sources are described. The basic physical principles of laser-driven neutron production and the current state-of-the-art of production techniques are outlined. The potential developments and the role of such sources in the landscape of neutron sources in the future are critically commented on.

Despite the technological advancement in blood-contacting biomedical devices, issues related to thrombosis remain a persistent challenge. These devices not only include implants such as artificial heart valves and stents but also surgical tools and instruments. This makes hemocompatibility an important parameter to be considered before developing any material for a blood-contacting device. The two oldest methods, including the mechanical tilting method and the free-hemoglobin method, lack temporal accuracy and quantitative analysis. Our work gives an accurate and quantitative analysis to measure the blood clotting time of various materials that can be used as implant devices. The system relies on measuring the change of reflectance as blood clots on a surface and measures the clotting time and rate by analyzing the time dependent reflectance curve. The system consists of an automated injection system, a heater and temperature controller, a red laser and polarizer assembly, and a highly sensitive photodetector. As the blood clotting process begins, the sample surface becomes turbid, causing a change in voltage in the detector. The time taken for this "voltage change" corresponds to clotting time. Our system shows a prothrombin time of 12.6 s and an activated partial thromboplastin time of 31.16 s on the PTFE surface, close to the control due to its hydrophobicity. The electronics and device configuration used in our system give a temporal resolution of 5.7 ± 0.6 ms in the clotting time determination. Our design is compact, precise, accurate, and devoid of manual observation and errors.

The focus of this paper is on the development of an apparatus capable of rapid and precise temperature control of liquid samples circulated through a small-bore glass capillary over a range from -20 to 130 °C, with stability better than 10 mK rms. Temperature regulation is achieved by lowering the capillary into a dry gas stream that flows through a narrow slit in a wide aluminum nozzle whose temperature is controlled by two thermoelectric modules (TEMs) that transfer heat between the nozzle and coolant flowing through a heatsink. Rapid thermal equilibration between the capillary and nozzle occurs primarily through conductive heat exchange with the flowing gas. The performance of the temperature controller is well described by a heat-transfer model, with low heat-capacity components enabling fast temperature slew rates. The temperature-control head is compact and can be fitted with customizable apertures suitable for visual access to the capillary and for transmitting focused electromagnetic radiation through it. However, the thermal cycling of the TEMs at high operating temperatures led to the rapid degradation of their cooling capacity. To mitigate this issue, separate low-(∼4 °C), room-, and high-temperature (∼85 °C) coolant reservoirs and pinch valves were used to select the coolant reservoir based on the target temperature, thereby limiting the maximum temperature experienced across the TEMs during thermal cycling and dramatically extending their operational lifetime. This apparatus was designed primarily for temperature-dependent, time-resolved x-ray scattering studies of biomolecules in solution but has also been used in time-resolved spectroscopic investigations.

Local shot noise spectroscopy with scanning tunneling microscopy (STM) has proven to be a powerful technique to investigate the electronic properties of quantum materials. It provides direct and non-invasive insight into the tunneling charge quanta or dynamics at the atomic scale. Due to the typically weak noise signal and the presence of low frequency spurious noise, local noise experiments require a high-resolution measurement amplifier. Here, we present a newly developed high-resolution noise amplifier that we implemented in three different STMs. Compared to our previous generation, we obtain more than a 20-fold improvement in the noise resolution, allowing us to resolve values of the effective charge as small as 0.01e. Our amplifier opens new possibilities for studying electronic properties in novel materials such as d-wave superconductors. In addition to this, it can give direct information about the local electron temperature in STM experiments.

The objective of the APEX (A Positron-Electron eXperiment) project is to magnetically confine and study positron-electron pair plasmas. For this purpose, a levitated dipole trap (APEX-LD) has been constructed. The magnetically levitated, compact (7.5-cm radius), closed-loop, high-temperature superconducting floating (F-)coil consists exclusively of a no-insulation rare-earth barium copper oxide winding pack, solder-potted in a gold-plated-copper case. A resealable in-vacuum cryostat facilitates cooling (via helium gas) and inductive charging of the F-coil. The 70-min preparation cycle reliably generates persistent currents of ∼60 kA-turns and an axial magnetic flux density of B0 ≈ 0.5 T. We demonstrate levitation times in excess of 3 h with a vertical stability of σz < 20 μm. Despite being subjected to routine quenches (and occasional mechanical shocks), the F-coil has proven remarkably robust. We present the results of preliminary experiments with electrons and outline the next steps for injecting positron bunches into the device.