Browse Topic: Superconductors
When it comes to quantum technology, niobium is making a comeback. For the past 15 years, niobium has been sitting on the bench after experiencing a few mediocre at-bats as a core qubit material
The NIST camera is made up of grids of ultrathin electrical wires, cooled to near absolute zero, in which current moves with no resistance until a wire is struck by a photon. In these superconducting-nanowire cameras, the energy imparted by even a single photon can be detected because it shuts down the superconductivity at a particular location (pixel) on the grid. Combining all the locations and intensities of all the photons makes up an image
MIT researchers have developed a quantum computing architecture that aims to enable extensible, high-fidelity communication between superconducting quantum processors
A new fabrication methodology addresses the need for a thin, double-sided circuitry board capable of low crosstalk between sensors and low loss in transmission lines
Superconductors — materials that conduct electricity without resistance — provide a macroscopic glimpse into quantum phenomena, which are usually observable only at the atomic level. Superconductors are found in medical imaging, quantum computers, and cameras used with telescopes. But often, they are expensive to manufacture and prone to error from environmental noise
Niobium metal is used in the implantation of a variety of superconducting quantum devices
Characterizing microstrip superconducting film at millimeter-wave frequencies is difficult without undergoing a complex thin film fabrication process. This characterization includes measuring the ohmic loss at a resolution of 10100 parts per million (ppm
NASA Goddard Space Flight Center has developed a magnetic shielding design that features simplicity, ease of use, reproducibility, longevity, and scalability. It does not require activation, monitoring, or wiring. The invention uses the superconducting “proximity effect” and/or the “inverse proximity effect” to form a spatially varying order parameter. When designed to expel magnetic flux from a region of space, the proximity effect(s) are used in concert to make the superconducting order parameter strongly superconducting in the center and more weakly superconducting toward the perimeter. The shield is then passively cooled through the superconducting transition temperature
Superconductivity, where electrical currents travel unhindered through a material, has many practical uses. It is used in applications extending from MRIs in hospitals to the cavities of particle accelerators. However, practical exploitation of superconductivity also presents many challenges
This superconducting magnet developed at NASA Goddard Space Flight Center comprises a superconducting wire wound in adjacent turns about a mandrel to form the superconducting magnet; a thermally conductive potting material configured to fill interstices between the adjacent turns; and a voltage limiting device disposed across each end of the superconducting wire, and is configured to prevent a voltage excursion across the superconducting wire during quench of the superconducting magnet. The thermally conductive potting material and the superconducting wire provide a path for dissipation of heat
Multi-element compounds have been used ubiquitously in various applications, including electronics, optics, opto-electronics, thermoelectrics, superconductivity, and the recently developed application of spintronics. Besides being the main components of some of these devices, the bulk form of these compounds is needed as a standard for fundamental property characterizations as well as the starting materials for thin-film deposition. Hence, the chemical purity and crystalline quality of these bulk compounds are critical for the applications
There has been a great deal of interest in building bolometers from hightemperature superconductors due to their high transition temperatures and the associated ease of cooling. High-temperature superconducting (high Tc) bolometers are difficult to fabricate because the standard method of thermal isolation is not compatible with these materials. A method is described that allows a standard thermal isolation technique (using amorphous silicon nitride membranes) to be used with high-temperature superconductors
A thin-film magnetic thermometer with integrated, superconducting quantum interference device (SQUID) readout has been designed for fast, precision temperature measurements in the 10-mK range. The compact magnetic thermometer consists of a miniature DC SQUID susceptometer with a dilute paramagnetic alloy deposited in one of the two series-configured, gradiometric SQUID pickup loops that form the SQUID inductance. Directly sensing the magnetic signal with the SQUID eliminates coupling losses that occur by transformer-coupling the signal to a remotely located SQUID, usually operating at a higher temperature, and consequently, with a higher noise floor
The superconducting nanowire single-photon detector (SNSPD) arrays created in this innovation were fabricated using a WSi nanowire process. A gold mirror layer is deposited on an oxidized silicon wafer, and amorphous-state WSi is sputtered from a compound target at a thickness of 5 nm. The WSi nanowire is embedded at the center of a three-layer vertical optical cavity consisting of two silica layers and a titanium oxide anti-reflective coating. The layer thicknesses were chosen, on the basis of simulations and measured material parameters, to optimize efficiency at the target communication wavelength of 1,550 nm, and to minimize the polarization dependence of the detector response
High-tech specks called quantum dots could bring brighter, more vibrant color to mass market TVs, tablets, phones and other displays. A new technology called 3M quantum dot enhancement film (QDEF), unveiled at the 248th National Meeting & Exposition of the American Chemical Society (ACS), has the potential to efficiently make liquid crystal display (LCD) screens more richly colored. That’s because quantum dot, or “QD,” displays need less energy compared to other high-color options. QDs are superconducting crystals so small that 10,000 could fit across the width of a human hair
The European Organization for Nuclear Research (CERN) requires new magnets that are smaller than their predecessors to accommodate new instrumentation. Because of their size, these magnets need to generate a 24 percent stronger magnetic field and the structure must provide for near-zero deformation of the conductor. Even a small deformation could increase the electrical resistance and raise the temperature enough to cause the conductor to lose its superconducting state. Engineers addressed this challenge using ANSYS electromagnetic, thermal, and structural simulation tools. Coupling the multiphysics domains in the ANSYS® Workbench® environment allowed the team to optimize the design by simultaneously considering all of the physics
Low-temperature, contactless radio-frequency (RF) probing systems are necessary for characterizing sensors operating at liquid nitrogen or helium temperatures, and based on superconducting materials. The design and operation of the contactless RF probing systems relies on strong electromagnetic coupling that takes place between two different microwave transmission lines oriented in close proximity, but not in contact with each other, to ensure high thermal isolation. The goal of this work is to develop a reliable, easily constructed, less expensive, contactless RF probe for characterizing microwave integrated circuits (MICs) and devices embedded in sensors fabricated on conformal or non-planar substrates, at elevated or cryogenic temperatures
The future looks bright, light, and green—especially where aircraft are concerned. The division of NASA’s Fundamental Aeronautics Program called the Subsonic Fixed Wing Project is aiming to reach new heights by 2025–2035, improving the efficiency and environmental impact of air travel by developing new vcapabilities for cleaner, quieter, and more fuel efficient aircraft
Flexible circuits with superconducting wiring atop polyimide thin films are being studied to connect large numbers of wires between stages in cryogenic apparatus with low heat load. The feasibility of a full microstrip process, consisting of two layers of superconducting material separated by a thin dielectric layer on 5 mil (≈0.13 mm) Kapton sheets, where manageable residual stress remains in the polyimide film after processing, has been demonstrated. The goal is a 2-mil (≈0.051-mm) process using spin-on polyimide to take advantage of the smoother polyimide surface for achieving high-quality metal films. Integration of microstrip wiring with this polyimide film may require high-temperature bakes to relax the stress in the polyimide film between metallization steps
Adiabatic demagnetization refrigerators (ADR) are operated in space to cool detectors of cosmic radiation to a few 10s of mK. A key element of the ADR is a superconducting magnet operating at about 0.3 K that is continually energized and de-energized in synchronism with a thermal switch, such that a piece of paramagnetic salt is alternately warm in a high magnetic field and cold in zero magnetic field. This causes the salt pill or refrigerant to cool, and it is able to suck heat from an object, e.g., the sensor, to be cooled. Current has to be fed into and out of the magnets from a dissipative power supply at the ambient temperature of the spacecraft. The current leads that link the magnets to the power supply inevitably conduct a significant amount of heat into the colder regions of the supporting cryostat, resulting in the need for larger, heavier, and more powerful supporting refrigerators. The aim of this project was to design and construct high-temperature superconductor (HTS
Small size, wide spectral bandwidth, and highly multiplexed detector readout are required to develop powerful multi-beam spectrometers for high-redshift observations. Currently available spectrometers at these frequencies are large and bulky. The grating sizes for these spectrometers are prohibitive. This fundamental size issue is a key limitation for space-based spectrometers for astrophysics applications
A fabrication process has been developed for cryogenic in-line filtering for the bias and readout of ultrasensitive cryogenic bolometers for millimeter and submillimeter wavelengths. The design is a microstripline filter that cuts out, or strongly attenuates, frequencies (10–50 GHz) that can be carried by wiring staged at cryogenic temperatures. The filter must have 100-percent transmission at DC and low frequencies where the bias and readout lines will carry signal. The fabrication requires the encapsulation of superconducting wiring in a dielectric-metal envelope with precise electrical characteristics. Sufficiently thick insulation layers with high-conductivity metal layers fully surrounding a patterned superconducting wire in arrayable formats have been demonstrated
A document describes the fabrication of a two-dimensional microcalorimeter array that uses microstrip wiring and integrated heat sinking to enable use of high-performance pixel designs at kilo - pixel scales (32×32). Each pixel is the high-resolution design employed in small-array test devices, which consist of a Mo/Au TES (transition edge sensor) on a silicon nitride membrane and an electroplated Bi/Au absorber. The pixel pitch within the array is 300 microns, where absorbers 290 microns on a side are cantilevered over a silicon support grid with 100-micron-wide beams. The high-density wiring and heat sinking are both carried by the silicon beams to the edge of the array. All pixels are wired out to the array edge
The temperature dependence of fluxoid quantization in a superconducting loop. The sensitivity of the device is expected to surpass that of other super-conducting-based bolometric devices, such as superconducting transition-edge sensors and superconducting nanowire devices. Just as important, the proposed device has advantages in sample fabrication. Two challenges of transition edge sensor fabrication are the reproducibility of the superconducting transition temperature, Tc , and the sharpness of the transition. In the proposed device, unlike in other devices, the sample would remain in the superconducting state at all times during operation. That is to say it would be maintained at an absolute temperature, T, below its superconducting
Electrostrictive ceramic actuators that can function at low temperatures have been developed for controlling the shapes of mirrors in the Next Generation Space Telescope (NGST). On Earth, electrostrictive ceramic actuators may be useful for fine control of the positions of objects in cryogenic laboratory apparatuses and in industrial cryogenic (including superconducting) systems
Superconducting-nanowire single-photon detectors (SNSPDs) in which NbxTi1–xN (where xerve as the superconducting materials have shown promise as superior alternatives to previously developed SNSPDs in which NbN films serve as the superconducting materials. SNSPDs have potential utility in optical communications and quantum cryptography
A computational- simulation study of distributions of electric current and temperature in brushes and slip rings in two model homopolar- motor/generator configurations was performed in support of the development, by the U.S. Navy, of a superconducting homopolar motor/generator (SCHPMG) machine for ship propulsion. Electrical-contact performance (more specifically, brush/slip-ring contact performance) is a limiting factor in the performance of an SCHPMG machine. The present study and similar studies are needed to gain understanding of brush/slip-ring contact performance in order to enable optimal design of brushes for homopolar machines
An improved readout scheme has been proposed for high-resolution thermometers, (HRTs) based on the use of superconducting quantum interference devices (SQUIDs) to measure temperature- dependent magnetic susceptibilities. The proposed scheme would eliminate counting ambiguities that arise in the conventional scheme, while maintaining the superior magnetic-flux sensitivity of the conventional scheme. The proposed scheme is expected to be especially beneficial for HRT-based temperature control of multiplexed SQUID-based bolometer sensor arrays
According to a proposal, a phenomenon associated with excitation of quasi- particles in certain superconducting quantum devices would be exploited as a means of detecting photons with exquisite sensitivity. The phenomenon could also be exploited to perform medium-resolution spectroscopy. The proposal was inspired by the observation that Coulomb blockade devices upon which some quantum logic gates are based are extremely sensitive to quasiparticles excited above the superconducting gaps in their leads. The presence of quasiparticles in the leads can be easily detected via the charge states. If quasiparticles could be generated in the leads by absorption of photons, then the devices could be used as very sensitive detectors of electromagnetic radiation over the spectral range from x-rays to submillimeter waves
A process that employs silicon-on-insulator (SOI) substrates and silicon (Si) micromachining has been devised for fabricating wide intermediate frequency band (wide-IF) superconductor/ insulator/ superconductor (SIS) mixer devices that result in suspended gold beam leads used for radio-frequency grounding. The mixers are formed on 25-µm-thick silicon membranes. They are designed to operate in the 200 to 300 GHz frequency band, wherein wide-IF receivers for tropospheric- chemistry and astrophysical investigations are necessary. The fabrication process can be divided into three sections
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