Michael Starkloff

The paper describes a compact 18-channel bias source for driving 10 V programmable Josephson voltage standard arrays suitable for DC, AC and dynamic measurements up to 1 kHz. The PJVS bias source is to be used for Planck balance experiments. The switching time between voltage steps is in the range of microseconds. A main feature is the synchronizat...

Abstract — In this work we present a method to use the AC quantum voltmeter setup for the measurement of ac currents up to 1 kHz frequencies. Besides the typical dc and ac voltage calibrations of programmable Josephson voltage standard arrays the area of application is extended. A commercial Fluke 5720A calibrator was investigated as current source...

The paper describes a dry-cooled AC quantum voltmeter system operated up to kilohertz frequencies and 7 V rms. A 10 V programmable Josephson voltage standard (PJVS) array was installed on a pulse tube cooler (PTC) driven with a 4 kW air-cooled compressor. The operating margins at 70 GHz frequencies were investigated in detail and found to exceed 1...

The AC Quantum Voltmeter, which was a breakthrough as an accredited, industrial-tested, fast and easy-to-use DC and AC voltage quantum-based calibrating system, has now been taken one step further with new extensive capabilities covering resistance and current measurements. Using equipment readily available in calibration laboratories, the new Quan...

This paper describes the properties of a 10 V programmable Josephson voltage standard (PJVS) array operated in a cryocooler. The operating margins at 70 GHz frequencies are discussed and compared to liquid helium cooling. A crucial factor is the limited heat conduction between PJVS chip and cold stage. A method is presented to estimate the heat con...

This paper describes the development of an automated ac quantum voltmeter toward a turnkey system, which can be used for calibration of common dc and ac voltage standards. The setup was tested in an accredited commercial calibration laboratory to characterize Fluke 5700A calibrators and voltage standards. The measured voltage in dependence on vario...

This paper describes the performance of a new turn-key AC quantum voltmeter, an AC Josephson voltage standard system, used for calibration of common DC and AC voltage standards. The capabilities and handling of the system in an industrial environment were investigated and are discussed here. Several Fluke 5700A series calibrators were tested and th...

An ac quantum voltmeter based on a 10 V programmable Josephson array that is simple to use, provides dc and ac calibration up to kHz range for equipment widely used in metrology, and ensures direct traceability to a quantum-based standard, is developed. This ac quantum voltmeter is proven to match conventional Josephson standard systems at dc and e...

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 in order to get an estimate of the intrinsic noise. We compare different approaches to estimate the noise of our lates...

A Voltage Calibrator based on a 10-V programmable Josephson Array that is simple to use, provides DC and AC calibration up to kHz range for industry-common equipment, and ensures direct traceability to a quantum-based standard, is under development. This device has proven to excel conventional DC standard systems and will extend into low frequency...

Geophysical exploration is getting more and more difficult—many of the easily explorable ore-bodies have been discovered and are already being exploited. Finding new mines requires new technologies and tools. Transient electromagnetics (TEM) is widely used in mineral exploration, but conventional sensors (especially induction coils) cannot fulfil t...

Cryogenic bolometers are adequate sensing devices for sub-millimeter observations. They are used for instrumentation in radio telescopes like the Atacama Pathfinder Experiment (APEX), which is a 12-m radio telescope in Chile’s Atacama desert. Through its thin and dry atmosphere, star formation in the red-shifted early universe can be observed.A sui...

The microwave properties of microstrip lines used for Josephson voltage standard circuits at frequencies from 70 to 75 GHz were investigated at a temperature of 4.2 K. Our measurements quantify the different loss sources. The excitation of a parasitic substrate mode is postulated, demonstrated by microwave modelling and confirmed by experiments. Th...

We describe the development and fabrication of the sub-millimeter APEX (Atacama pathfinder experiment) bolometer camera (SABOCA) and its installation at the APEX radio telescope in Chile. SABOCA has 37 bolometers for a wavelength of about 0.35 mm. The bolometers with superconducting transition-edge sensors are read out by superconducting quantum in...

We present the concept and experimental set-up of a passive submillimeter-wave stand-off imaging system for security applications. Our ambition is the design of an application-ready and user-friendly camera providing high sensitivity and high spatial resolution at video frame rates. As an intermediate step towards this goal, the current prototype a...

This paper describes the experiences and operational parameters of the Josephson voltage system cooled by closed cycle refrigerator produced by HYPRES, INC., USA and operated in CZECH METROLOGY INSTITUTE. The change of the cooling system was required and the new cooling system was implemented by SUPRACON AG. The overall increase in operational para...

As reported before,1, 2 Safe VISITOR (Safe VISible, Infrared and Terahertz Object recognition) is a German project to build a passive security camera which visualizes sub-mm wavelengths using cooled bolometer arrays. This camera could be used for a variety of application scenarios, such as airport screenings or to protect military camps. In all cas...

The Submillimetre APEX Bolometer Camera, SABOCA, was successfully commissioned in March 2009 for operation as a facility instrument on the 12-metre APEX telescope, located on Llano de Chajnantor at an altitude of 5100 m. This new camera for the 350-μm atmospheric window uses superconducting bolometers and was built by the Max-Planck Institute for R...

A commercially available and fully automated 10-V Josephson voltage standard system with a liquid helium free cooling has been developed as a result of the cooperation between the Institute of Photonic Technology and Supracon AG, both in Jena, Germany. The system operates with an array of 19 700 superconductor-insulator-superconductor Josephson tun...

Security solutions with the purpose to detect hidden objects underneath the clothing of persons are desired in many environments. With the variety of application scenarios criteria like flexibility and mobility become more important. So, many developments trend to focus on cameras, which can image scenes from a distance. This new generation of tool...

Cryogenic bolometers detect radiation by measuring the temperature increase in an appropriate absorber. To achieve sufficient detector sensitivity, we place the bolometer on a SiN membrane. Thermal coupling is further decreased by patterning the membrane in the shape of a platform suspended by several beams. We will describe the fabrication process...

A commercially available complete microprocessor controlled, fully automated 10 Volt Josephson voltage standard system was developed in cooperation between IPHT and Supracon. The system operates with an array of altogether 19,700 SIS Josephson tunnel junctions. A direct comparison between two such systems showed an uncertainty of 2 times 10<sup>-10...

Terahertz (THz) cameras are expected to be a powerful tool for future security applications. If such a technology shall be useful for typical security scenarios (e.g. airport check-in) it has to meet some minimum standards. A THz camera should record images with video rate from a safe distance (stand-off). Although active cameras are conceivable, a...

The SuperCOnducting Terahertz Imager (SCOTI) is a small Cassegrain-type telescope with a scanning secondary mirror designed for a frequency of 0.34 THz. It can map objects at a distance of 5 meter using a small array of superconducting bolometers. The resolution at the object area is about 1 cm. Using SCOTI purely passive images of interesting obje...

A commercially available complete m icroprocessor controlled, f ully au tomated 10 Volt Jos ephson voltage standard system operated with a cryocooler was developed in cooperation between IPHT and Supracon. The system operates with an array of altogether 19,700 SIS Josephson tunnel junctions. A direct comparison to a helium-based system showed an ag...