More than 50 years ago superconducting quantum interference devices (SQUIDs) were invented. Since then many applications opened up. Already in a 1980 workshop (Weinstock and Overton 1981 SQUID Applications to Geophysics (Society of Exploration Geophysicists)) the application SQUIDs geosciences was reviewed. The fabrication cooling technologies, electronics other system components underwent significant improvement within past years. Thus, are today better suited, more sensitive effective as...

We report on the development of a new family magnetic field sensors with exceptionally low noise, as 0.3 fT Hz − 1/2. Beside this, they exhibit high usable voltage swings more than 150 µVpp and tolerable background fields during cool-down up to 6.5 mT. In operation mode recover completely from magnetization pulses 76 mT, which makes them well suited for applications such low-field resonance imaging. With respect their easy reliable use resolution in sub-fT Hz 1/2 range, presented SQUID are...

Abstract We report on the design and implementation of AQFP buffer gates utilizing cross-type Nb/AlOx/Nb Josephson junctions with IC 20 µA, designed to operate at mK temperatures. We, therefore, discuss considerations, circuit simulation optimization their technological implementation. The preliminary results test 4.2 K are demonstrated focusing performance. Particularly, we emphasize current sensitivity based output switching probability. measurement results, show a narrow grayzone width...

We report on a technology for the fabrication of sub-micrometer sized cross-type Josephson tunnel junctions in niobium technology. present scheme and properties with linear dimensions from 10 down to 0.6 µm. Sidewall passivation is achieved by anodization as well planarizing SiO self-aligned deposition step. The measured ratio sub-gap resistance normal about 35. Because their low current parasitic capacitance such are suited applications like high resolution SQUIDs.

Quantum information processing based on light has invigorated research the production and detection of single photons. The authors present an innovative scheme for weak microwave signals, a superconducting current-biased Josephson junction. In contrast to detectors that absorb photons, this system is optimized such amplitude classical photon field triggers detection.

We studied and optimised the properties of ultrathin superconducting niobium nitride films fabricated with a plasma-enhanced atomic layer deposition (PEALD) process. By adjusting process parameters, chemical embedding undesired oxygen into was minimised film structure consisting mainly polycrystalline small fraction amorphous oxide oxo-nitrides were formed. For this composition critical temperature 13.8 K current densities 7 × 106 A cm–2 at 4.2 measured on 40 nm thick films. fundamental...

We report on the development of an ultralow noise thin-film based SQUID magnetometer. A niobium pickup coil is connected to input a current sensor. The low capacitance used sub-micrometer cross-type Josephson junctions enable superior performance device. Application scenarios e.g. in geophysics and ultra-low field magnetic resonance imaging are discussed.

To measure the noise performance of highly sensitive SQUID magnetometer systems directly is nearly impossible due to superimposed external noise. In magnetically unshielded environments in particular one needs sophisticated methods order get an estimate intrinsic We compare different approaches our latest Earth's magnetic field and results with measurements (and superconductive) shielding.

Geophysical exploration is getting more and difficult—many of the easily explorable ore-bodies have been discovered are already being exploited. Finding new mines requires technologies tools. Transient electromagnetics (TEM) widely used in mineral exploration, but conventional sensors (especially induction coils) cannot fulfil needs anymore: deep targets, very conductive targets or under overburden (or sometimes only) detected using SQUIDs. In this paper we will focus on low temperature...

We report on the development of highly sensitive SQUIDs featuring sub-micrometer loop dimensions. The integration high quality and low capacitance SIS Nb/AlOx/Nb cross-type Josephson tunnel junctions results in white flux noise levels as 66 nΦ0 Hz−1/2, well below state-of-the-art values their Nb-based counterparts based constriction type junctions. Estimation spin sensitivity best yield Sμ1/2 < 7μB Hz−1/2 region, suitable for investigation small systems. discuss fabrication challenges, show...

Forty years after the first application of Superconducting Quantum Interference Devices (SQUIDs) [1], [2] for geophysical purposes, they have recently become a valued tool mineral exploration. One most common applications is time domain (or transient) electromagnetics (TEM), an active method, where inductive response from ground to changing current (mostly rectangular) in loop on surface measured. After transmitter coil switched, eddy currents are excited ground, which decay manner dependent...

We present a configuration of LTS dc SQUID magnetometers that is suited for an absolute measurement the vector components Earth's magnetic field with white noise level about 6 fT Hz−1/2. Due to its periodic voltage–flux characteristic, SQUID's output voltage generally corresponds set equidistant fluxes or strengths. To resolve this ambiguity, we introduce coplanar SQUIDs integrated on single chip, which exhibit effective areas differing by several orders magnitude. The possible strengths...

We report on the development of nearly quantum limited SQUIDs with miniature pickup loop dimensions. The implemented high quality and low capacitance cross-type Nb/AlOx/Nb Josephson junctions offer large ICRN-products therefore enable an exceptional noise level SQUIDs. Devices dimensions 1 μm exhibit white flux levels as 45 nΦ0 Hz−1/2 corresponding to energy resolution ε about h at 4.2 K, being Planck's constant. Moreover, usable voltage swings devices 300 μV allow highly sensitive easy...

We report on the properties of submicrometer-sized Josephson tunnel junctions fabricated in a cross-type technology. The quality is indicated by current density profiles obtained from Fraunhofer diffraction patterns. capacitance determined evaluation Fiske steps. strong improvement SQUID parameters, like usable voltage swing and intrinsic flux noise due to use these low-capacitance junctions, shown magnetometers. In addition, very high stability against magnetic fields up several mT during...

A SQUID current sensor with integrated input coil has been designed and fabricated using our new technology Nb–AlOx–Nb cross-type Josephson junctions. The white noise level of the was measured to be 1 μΦ0 Hz−1/2, corresponding a resolution about 110 fA Hz−1/2. superconducting transformer turns ratio 19:1 standard Nb technology. chip size is 12.5 mm × mm. Three chips were assembled in flip-chip configuration yielding an effective 48:1. this at sensitivity 4.1 nA/Φ0. second stage amplifier...

For the first time a mobile underwater full tensor magnetic gradiometer (FTMG) system based on low-T c superconducting quantum interference devices (SQUIDs) has been deployed in order to scan sea floor for magnetized targets. The application is mainly focused waste deposits and unexploded ordnance (UXO), but could also include shallow geological features as well archaeological remains. main methods detection localisation of UXO are side sonar scanning mapping. While modern scanners can...

Carrier mobilities and concentrations were measured for different p- n-type silicon materials in the temperature range 0.3–300 K. Simulations show that experimentally determined carrier are best described this by Klaassen's model. Freeze-out reduces concentration with decreasing temperature. Freeze-out, however, depends on dopant type initial concentration. Semi-classical calculations useful only temperatures above 100 Otherwise quantum mechanical required.

A planar superconducting quantum interference device (SQUID) magnetometer consisting of a parallel gradiometer SQUID with integrated input coils connected to an on-chip pickup loop was designed and fabricated in conventional niobium technology. bootstrap circuitry (SBC) incorporating suitable current voltage feedbacks also into the design. For inductance Ls = 350 pH chip size 5 × mm2, field resolution voltage-biased reached <5 fT Hz−1/2 circuit ordinary preamplifier. We observed that...

We present and discuss results for the experimental evaluation of bi-SQUIDs with shunted submicron cross-type Josephson tunnel junctions characterized by low capacitance. Such a technology, meant SQUID sensors, was developed to enable unshielded operation sensors avoid unwanted flux trapping. The obtained voltage response swing is as high 60 µV. observed differences between measured theoretically predicted responses are analyzed possible ways approach triangular shape discussed. An improved...

We report the performance of a reliable three-dimensional nanometer-sized Superconducting QUantum Interference Device (SQUID). The use superconductor-isolator-superconductor Nb/Al-AlOx/Nb Josephson tunnel junctions together with small SQUID loop dimensions permits high modulation depth SQUID's critical current and thus leads to very low intrinsic flux noise device. In particular, we present electrical characterization including detailed investigations. At 4.2 K, two-stage measurements as...

We report on the development of a three-axis absolute vector magnetometer suited for mobile operation in Earth's magnetic field. It is based low critical temperature dc superconducting quantum interference devices (LTS SQUIDs) with sub-micrometer sized cross-type Josephson junctions and exhibits white noise level about 10 fT/Hz(1/2). The width strip lines restricted to less than 6 μm order avoid flux trapping during cool-down magnetically unshielded environment. long-term stability...

In this paper, we present new integrated on-chip planar-type superconducting quantum interference device (SQUID) first order gradiometers, which are manufactured by a mix and match fabrication technology combining sub-μm sized Josephson junctions (JJs) with cm-scale pickup loops. The is described the design schematically shown. These sensors have high voltage swing low flux noise provide thus best so far reported gradient resolution of about gradiometers were developed implemented in...