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We present the results of experimentation with a superconducting nanowire that can be operated in two detection modes: i) as a kinetic inductance detector (KID) or ii) as a single photon detector (SPD). When operated as a KID mode in linear mode, the detectors are AC-biased with tones at their resonant frequencies of 45.85 and 91.81MHz. When operated as an SPD in Geiger mode, the resonators are DC biased through cryogenic bias tees and each photon produces a sharp voltage step followed by a ringdown signal at the resonant frequency of the detector. We show that a high AC bias in KID mode is inferior for photon counting experiments compared to operation in a DC-biased SPD mode due to the small fraction of time spent near the critical current with an AC bias. We find a photon count rate of $\Gamma_{KID} = 150~$photons/s/mA in a critically biased KID mode and a photon count rate of $\Gamma_{SPD} = 10^6~$photons/s/mA in SPD mode.
This dissertation additionally presents simulations of a DC-biased, frequency-multiplexed readout of SNSPD devices in Advanced Design System (ADS), LTspice, and Sonnet. A multiplexing factor of 100 is achievable with a total count rate of $>5$MHz. This readout could enable a 10000-pixel array for astronomy or quantum communications. Finally, we present a prototype array design based on lumped element components. An early implementation of the array is presented with 16 pixels in the frequency range of 74.9 to 161MHz. We find good agreement between simulation and experimental data in both the time domain and the frequency domain and present modifications for future versions of the array.
A significant increase in leakage currents is almost always observed in near-ideal devices upon annealing. In contrast, non-ideal devices dominated by leakage currents annealed at 150 C to 250 C exhibit a significant decrease in such currents.
Niobium (Nb) based Josephson junction devices were fabricated with barriers containing two ferromagnetic layers separated by a normal metal space layer. In device operation, electrons in the superconductor are injected into the ferromagnets, causing the superconductor wavefunction to shift its phase and decay in amplitude. Such devices have two different states that depend on the relative magnetization of their ferromagnetic barrier layers, parallel or antiparallel. In these different states, the junctions have different phase shifts and critical currents. Superconducting circuits containing these devices can be designed to operate as memory cells using either one of these outputs.
To quantify the shift in phase and amplitude decay of the wavefunction through a common ferromagnet, permalloy, a series of Nb/permalloy/Nb Josephson junctions with varying ferromagnetic layer thicknesses were fabricated. Data have shown that the optimal thickness of a fixed layer composed of permalloy is 2.4 nm, as it shifts the wavefunction phase to π/2, its “pivot point.” If set to precisely this value, the free layer in SFNF'S junctions will switch the junction into either the 0 or π state depending on its magnetic orientation. To minimize the free-layer switching energy dilute Cu-permalloy alloy [Cu0.7(Ni80Fe20)0.3] with a low magnetic saturation (Ms of ~80 emu/cm3) was used as the free layer. These devices exhibit switching energies at small magnetic fields, demonstrating their potential use for low power non-volatile memory for superconductor circuits.
Lastly, to study the proximity effect using other potentially-useful ferromagnetic layers, measurements were performed on Nb/F bilayers and Nb/F/AlOx/Al tunnel junctions with ferromagnets Ni8Fe19, Ni65Fe15Co20, and Pd1-xNix. The dependence of the critical temperature of the bilayers and density of states that propagated through the ferromagnetic layer were studied as a function of thickness. From this study, crucial magnetic and electrical parameters like magnetic coherence lengths (ξF), exchange energy (Eex), and the rate of shift in the wavefunction’s phase and amplitude as a function of thickness were determined.
When you are sitting at the terminal waiting for your flight or taking the bus to get to work, have you ever thought about who used your seat last? More importantly, have you ever thought about the last time that seat was cleaned? Sadly, it is uncertain to see if it was properly sanitized in the last hour, yesterday, in the last week, or even last month. Especially during these tough times, everyone wants to be assured that they are always in a safe and healthy environment. Through the Founders Lab, our team is collaborating with an engineering capstone team to bring automated seat cleaning technology into the market. This product is a custom-designed seat cover that is tear-resistant and provides a sanitary surface for anyone to sit on. When someone leaves the seat, a pressure sensor is triggered, and the cover is replaced with a secondary cover that was stored in a UV radiated container. The waterproof fabric and internal filters prevent spills and food crumbs from remaining when the user changes. The reason for bringing this product into the market is due to the unsanitary conditions in many high traffic areas. This technology can be implemented in public transportation, restaurants, sports stadiums, and much more. It will instantly improve the efficiency of sanitation for many businesses and keep a promise to its users that they will never bring something they sat on back home. #Safeseating
Our project is to create a simplified, portable, modular electrocardiogram known as ECG/EKG. Most medical facilities, including hospitals, clinics, and skilled nursing facilities, still rely on traditional 12-lead EKG equipment consisting of a large cart with long 10 wires. These wires can be a pain to constantly detangle and rearrange to determine a person’s heart conditions. This creates issues in fast paced scenarios such as when a patient is experiencing a heart attack and needs an EKG stat. Additionally, the current technology can be somewhat unreliable at determining heart conditions, causing providers to request multiple EKG’s for patients. With our improved versatile EKG, we can help solve these issues and implement additional outpatient use with its portable features. This can be done by remotely monitoring heart conditions during activities such as exercise, sleep, or stressful events, without worrying about wire disturbance.
Our project is to create a simplified, portable, modular electrocardiogram known as ECG/EKG. Most medical facilities, including hospitals, clinics, and skilled nursing facilities, still rely on traditional 12-lead EKG equipment consisting of a large cart with long 10 wires. These wires can be a pain to constantly detangle and rearrange to determine a person’s heart conditions. This creates issues in fast paced scenarios such as when a patient is experiencing a heart attack and needs an EKG stat. Additionally, the current technology can be somewhat unreliable at determining heart conditions, causing providers to request multiple EKG’s for patients. With our improved versatile EKG, we can help solve these issues and implement additional outpatient use with its portable features. This can be done by remotely monitoring heart conditions during activities such as exercise, sleep, or stressful events, without worrying about wire disturbance.
Our project is to create a simplified, portable, modular electrocardiogram known as ECG/EKG. Most medical facilities, including hospitals, clinics, and skilled nursing facilities, still rely on traditional 12-lead EKG equipment consisting of a large cart with long 10 wires. These wires can be a pain to constantly detangle and rearrange to determine a person’s heart conditions. This creates issues in fast paced scenarios such as when a patient is experiencing a heart attack and needs an EKG stat. Additionally, the current technology can be somewhat unreliable at determining heart conditions, causing providers to request multiple EKG’s for patients. With our improved versatile EKG, we can help solve these issues and implement additional outpatient use with its portable features. This can be done by remotely monitoring heart conditions during activities such as exercise, sleep, or stressful events, without worrying about wire disturbance.
Our project is to create a simplified, portable, modular electrocardiogram known as ECG/EKG. Most medical facilities, including hospitals, clinics, and skilled nursing facilities, still rely on traditional 12-lead EKG equipment consisting of a large cart with long 10 wires. These wires can be a pain to constantly detangle and rearrange to determine a person’s heart conditions. This creates issues in fast paced scenarios such as when a patient is experiencing a heart attack and needs an EKG stat. Additionally, the current technology can be somewhat unreliable at determining heart conditions, causing providers to request multiple EKG’s for patients. With our improved versatile EKG, we can help solve these issues and implement additional outpatient use with its portable features. This can be done by remotely monitoring heart conditions during activities such as exercise, sleep, or stressful events, without worrying about wire disturbance.