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The structural versatility of light underpins an outstanding collection of optical phenomena where both geometrical and topological states of light can dictate how matter will respond or display. Light possesses multiple degrees of freedom such as amplitude, and linear, spin angular, and orbital angular momenta, but the ability to adaptively engineer the spatio-temporal distribution of all these characteristics is primarily curtailed by technologies used to impose any desired structure to light. We demonstrate a laser architecture based on coherent beam combination offering integrated spatio-temporal field control and programmability, thereby presenting unique opportunities for generating light by design to exploit its topology.

We present a multimode X -band rf pulse compression system suitable for a TeV-scale electron-positron linear collider such as the Next Linear Collider (NLC). The NLC main linac operating frequency is 11.424 GHz. A single NLC rf unit is required to produce 400 ns pulses with 475 MW of peak power. Each rf unit should power approximately 5 m of accelerator structures. The rf unit design consists of two 75 MW klystrons and a dual-moded resonant-delay-line pulse compression system that produces a flat output pulse. The pulse compression system components are all overmoded, and most components are designed to operate with two modes. This approach allows high-power-handling capability while maintaining a compact, inexpensive system. We detail the design of this system and present experimental cold test results. We describe the design and performance of various components. The high-power testing of the system is verified using four 50 MW solenoid-focused klystrons run off a common 400 kV solid-state modulator. The system has produced 400 ns rf pulses of greater than 500 MW. We present the layout of our system, which includes a dual-moded transmission waveguide system and a dual-moded resonant line (SLED-II) pulse compression system. We also present data on the processing and operation of this system, which has set high-power records in coherent and phase controlled pulsed rf.

Experiments at the FLASH facility at DESY have demonstrated that the higher order modes induced in superconducting cavities can be used to provide a variety of beam and cavity diagnostics. The axes of the modes can be determined from the beam orbit that produces minimum power in the dipole HOM modes. The phase and amplitude of the dipole modes can be used to obtain high resolution beam position information, and the phase of the monopole modes to measure the beam phase relative to the accelerator rf. For most superconducting accelerators, the existing higher order mode couplers provide the necessary signals, and the downmix and digitizing electronics are straightforward, similar to those for a conventional beam position monitor.

Bunch length and energy-z correlation measurements were performed on the high energy (28.5 GeV) electron test beam of the A-line and End Station A (ESA) facilities at the SLAC National Accelerator Laboratory. The longitudinal profile of each bunch was measured by imaging the synchrotron light emitted as the electrons traversed a highly dispersive bend after being streaked by a transverse rf deflecting cavity. In addition, high frequency diodes and pyroelectric detectors placed at a ceramic gap in the beam line were used to measure the length of the bunch in ESA.

For many decades High Energy Physics (HEP) instrumentation has been concentrated on detectors of ionizing radiation -- where the energy of incident particles or photons is sufficient to create mobile charge in gas, liquid, or solid material, which can be processed by front end electronics (FEE) to provide information about the position, energy, and timing of the incident radiation. However, recently-proposed HEP experiments need to sense or control EM radiation in the radiofrequency (RF) range, where ionization detectors are unavailable. These experiments can take advantage of emerging microelectronics developments fostered by the explosive growth of wireless data communications in the commercial sector. Moore's Law advances in semiconductor technology have brought about the recent development of advanced microelectronic components with groundbreaking levels of analog-digital integration and processing speed. In particular, RF \"System-on-Chip\" (RFSoC) platforms offer multiple data converter interfaces to the analog world (ADCs and DACs) having bandwidths approaching 10GHz and abundant digital signal processing resources on the same silicon die. Such devices eliminate the complex PC board interfaces that have long been used to couple discrete ADCs and DACs to FPGA processors, thus radically reducing power consumption, impedance mismatch, and footprint area, while allowing analog preconditioning circuits to be eliminated in favor of digital processing. Costed for wide deployment, these devices are helping to accelerate the trend towards \"software defined radio\" in several high-volume commercial markets. In this whitepaper we highlight some HEP applications where leading-edge RF microelectronics can be a key enabler.

We present a light field imaging system that captures multiple views of an object with a single shot. The system is designed to maximize the total light collection by accepting a larger solid angle of light than a conventional lens with equivalent depth of field. This is achieved by populating a plane of virtual objects using mirrors and fully utilizing the available field of view and depth of field. Simulation results demonstrate that this design is capable of single-shot tomography of objects of size \\(O\\)(1 mm\\(^3\\)), reconstructing the 3-dimensional (3D) distribution and features not accessible from any single view angle in isolation. In particular, for atom clouds used in atom interferometry experiments, the system can reconstruct 3D fringe patterns with size \\(O\\)(100 \\(\\)m). We also demonstrate this system with a 3D-printed prototype. The prototype is used to take images of \\(O\\)(1 mm\\(^3\\)) sized objects, and 3D reconstruction algorithms running on a single-shot image successfully reconstruct \\(O\\)(100 \\(\\)m) internal features. The prototype also shows that the system can be built with 3D printing technology and hence can be deployed quickly and cost-effectively in experiments with needs for enhanced light collection or 3D reconstruction. Imaging of cold atom clouds in atom interferometry is a key application of this new type of imaging device where enhanced light collection, high depth of field, and 3D tomographic reconstruction can provide new handles to characterize the atom clouds.

The unique monumental heritage of L'Aquila has been seriously damaged by the 2009 earthquake, but it can be successfully restored. Instead of providing temporary shelter for the inhabitants and start as soon as possible a restoration program, the day after the disaster, the National Civil Protection authority and the government, started an ambitious plan to provide the population with an almost permanent accommodation; i.e. the C.a.s.e. project which adopted a sophisticated anti-seismic technology and planned to build 4600 apartments. This article argues that this was an extremely questionable decision first of all for the city-planning, which has devastated the country-side surrounding L'Aquila and its landscape. It was also an extremely expensive measure, seriously damaging the inhabitants' social life and cultural identity, which is extremely difficult to revert and which has been taken ignoring the democratic will of the population and of its representatives.

The microwave SQUID multiplexer (umux) has enabled higher bandwidth or higher channel counts across a wide range of experiments in particle physics, astronomy, and spectroscopy. The large multiplexing factor coupled with recent commercial availability of microwave components and warm electronics readout systems make it an attractive candidate for systems requiring large cryogenic detector counts. Since the multiplexer is considered for both bolometric and calorimetric applications across several orders of magnitude of signal frequencies, understanding the bandwidth of the device and its interaction with readout electronics is key to appropriately designing and engineering systems. Here we discuss several important factors contributing to the bandwidth properties of umux systems, including the intrinsic device bandwidth, interactions with warm electronics readout systems, and aliasing. We present simulations and measurements of umux devices coupled with SLAC Microresonator RF (SMuRF) tone-tracking electronics and discuss several implications for future experimental design.

We present the details of a simulation suite for modeling the effects of readout with SLAC Microresonator RF (SMuRF) electronics. The SMuRF electronics are a warm readout and control system for use with superconducting microwave resonator-based detector systems. The system has been used with the BICEP/Keck program and will be used on the upcoming Simons Observatory and BICEP Array experiments. This simulation suite is a software implementation of the main SMuRF algorithms for offline analysis, modeling, and study. The firmware-implemented algorithms for calibration, resonator frequency estimation, and tone tracking present sources of potential bias or errors if not modeled properly. The simulator takes as input true detector signal, realistic resonator properties, and SMuRF-related user-controlled readout settings. It returns the final flux ramp-demodulated output of a detector timestream as would be passed to the experiment data acquisition system, enabling the analysis of the impact of readout-related parameters on the final science data. It is publicly available in Python with accompanying Jupyter notebooks for user tutorials.

We describe the newest generation of the SLAC Microresonator RF (SMuRF) electronics, a warm digital control and readout system for microwave-frequency resonator-based cryogenic detector and multiplexer systems such as microwave SQUID multiplexers (\\(\\mu\\)mux) or microwave kinetic inductance detectors (MKIDs). Ultra-sensitive measurements in particle physics and astronomy increasingly rely on large arrays of cryogenic sensors, which in turn necessitate highly multiplexed readout and accompanying room-temperature electronics. Microwave-frequency resonators are a popular tool for cryogenic multiplexing, with the potential to multiplex thousands of detector channels on one readout line. The SMuRF system provides the capability for reading out up to 3328 channels across a 4-8 GHz bandwidth. Notably, the SMuRF system is unique in its implementation of a closed-loop tone-tracking algorithm that minimizes RF power transmitted to the cold amplifier, substantially relaxing system linearity requirements and effective noise from intermodulation products. Here we present a description of the hardware, firmware, and software systems of the SMuRF electronics, comparing achieved performance with science-driven design requirements. We focus in particular on the case of large channel count, low bandwidth applications, but the system has been easily reconfigured for high bandwidth applications. The system described here has been successfully deployed in lab settings and field sites around the world and is baselined for use on upcoming large-scale observatories.