A precision measurement of the gravitational constant $G$ has been made using a beam balance. Special attention given to determining calibration, effect possible nonlinearity balance and zero-point variation The equipment, measurements, analysis are described in detail. value obtained for is $6.674\text{ }252(109)(54)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}\text{ }\text{ }{\mathrm{m}}^{3}\text{ }{\mathrm{kg}}^{\ensuremath{-}1}\text{ }{\mathrm{s}}^{\ensuremath{-}2}$. relative...

Since the quantum Hall resistance (QHR) measured with alternating current (ac) has reached state of an excellent standard impedance, we have realized a quadrature bridge two ac QHRs to accurately calibrate capacitance standards in terms SI value von-Klitzing constant, without need for any calculable artefact. The advantages measuring chain, experimental tests coaxial bridges involved and achieved relative uncertainty 6 × 10−9 (k = 1) are discussed.

We present the connection of two programmable Josephson arrays generating synchronous waveforms to measure impedance ratios—the two-terminal-pair bridge. This approach is more flexible than conventional bridges at same level uncertainty. The bridge can over a wider frequency range, range ratios bridges. Furthermore, phase angle between impedances take any value. As first application, we measurements 1 : resistance ratio 10 kΩ in 25 Hz and kHz. uncertainties are better few parts 108 hence...

A new type of graphene-based quantum Hall standards is tested for electrical metrology applications at alternating current (ac) and direct (dc). The devices are functionalized with Cr(CO)

We describe a novel double-shield configuration applied to ac quantum Hall devices which is very significant advance in that it eliminates the effect of all presently known losses. The resistance measured this way therefore an excellent standard impedance having relative uncertainty well below 1 × 10−8.

Arbitrary impedance ratios can be determined with high accuracy by means of a programmable Josephson system. For 1 : resistance ratio at 10-kΩ level, we demonstrate that the novel system allows measurements over wide frequency range from 25 Hz to 6 kHz. Uncertainties are in few parts 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> and thus comparable those conventional bridges. Two methods for four-terminal-pair have been...

Since 1990, the quantum Hall resistance measured with direct current (dc) has been established to represent and maintain dc unit thereby replaced former derivation from calculated inductance capacitance standards. Because of this success, it suggested measure effect alternating (ac) in way derive units resistance, consistently same effect. In paper, we recall relations between these units, their role determination von Klitzing constant fundamental constants involved conventional approach....

We present the results of a gravitational experiment which is based on microwave resonator. The force test mass acting resonator measured as function distance. No deviation from Newton's law level few parts in 10/sup -4/ near range has been found and constant G determined with relative accuracy 1.1/spl times/10/sup to be: G=(6.6719/spl plusmn/0.0008)/spl -11/ Nm/sup 2/ kg/sup -2/.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

We present a new method to measure the gravitational constant $G$. A beam balance compares weight of two 1-kg test masses and measures force field with statistical uncertainty $10\mathrm{ng}$. Two vessels in refined arrangement are used as masses. They have been filled water test. $G$ has determined an $240\mathrm{ppm}$. The next step is fill mercury. Because larger signal further refinement our experiment, we hope reach design $10\mathrm{ppm}$.

In this paper, it is shown that a quantum Hall resistor (QHR) which exhibits proportionality relationship between the deviation of resistance from RK/i and ac dissipation in system, represented by ρxx, can be used as primary standard resistance. As an example, calculable quadrifilar was calibrated against QHR at kilohertz frequencies. The agreement calibration using calculated frequency dependence better than 4 parts 108 1 kHz. This result achieved despite current ac-QHR. most important...

The quantum Hall resistance measured at frequencies in the kilohertz range shows frequency- and current-dependent deviations from quantized dc value. This has been attributed to capacitive effects which are reflected ac longitudinal resistance. Nulling results a current-independent criterion is close analogy case that effect with same as dc. allows application primary standard of impedance.

Alternating current measurements of double-shielded quantum Hall devices have revealed a fascinating property which only effect is capable: it can detect its own frequency dependence and convert to be used eliminate both them. According an experimentally verified model, the residual smaller than measuring uncertainty 1.3 × 10−9 kHz−1. In this way, highly precise standard impedance established, without having correct for any calculated need artefact with dependence. Nothing else like that...

In view of the progress achieved in field ac quantum Hall effect, Working Group Comite Consultatif d'Electricite et Magnetisme (CCEM) on AC Quantum Effect asked authors this paper to write a compendium which integrates their experiences with measurements resistance. addition important early work performed at Bureau International des Poids Mesures and National Physical Laboratory, UK, further experience has been gained during collaboration authors' institutes NRC, METAS, PTB, excellent...

This paper reports on the thermal Johnson-Nyquist noise of quantum Hall and longitudinal resistances, which were measured both without an applied current with externally alternating or direct current. The results verify expected behavior give interesting insights into effect. They also demonstrate that ac measuring techniques commonly used in impedance metrology can take as a signal, reliably tiny effects resolution 10 pV.

Precision measurements of the quantum Hall resistance with alternating current (ac) in kHz range were performed on epitaxial graphene order to assess its suitability as a standard impedance. The plateaus measured found be flat within one part 107. This is much better than for plain GaAs devices and shows that magnetic-flux-dependent capacitive ac losses device are less critical. observed frequency dependence about −8 × 10−8/kHz comparable absolute value positive devices, but negative sign...

A high-precision measurement of the Newtonian gravitational constant G by means a beam balance is being carried out at University Zürich. We have made test measurements in which force 103 kg water was used and determined with relative standard uncertainty 220 × 10-6. Currently, 13.5 mercury are progress. These not completed yet, but preliminary result presented.

Josephson impedance bridges have been reported to provide uncertainties close that from the best conventional when comparing two 10-kΩ resistors. The accuracy of a few parts in 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> has extended comparison 100-pF capacitance standards, significantly improving uncertainty for these measurements at power line frequencies. Preliminary quadrature are also presented with level 1.6 ×...

This paper describes the measurements of ac quantum Hall effect (QHE) in epitaxial graphene a set six different devices. In typical devices, capacitive losses cause negative frequency dependence resistance, contrast to positive observed GaAs one sample, very low dissipation was measured along with resistance decreasing by less than part 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> between 0 and kHz, which demonstrates potential QHE...

We investigate the $1/f$ noise properties of epitaxial graphene devices at low temperatures as a function temperature, current, and magnetic flux density. At currents, an exponential decay power spectral density with increasing temperature is observed that indicates mesoscopic conductance fluctuations origin below 50 K. higher deviations from typical quadratic current dependence occur result nonequilibrium conditions due to heating. By applying Kubakaddi theory [S. S. Kubakaddi, Phys. Rev. B...

A new coaxial measurement system has been developed to investigate the ac longitudinal resistance along high-potential side of quantum Hall (QHR). novel equivalent circuit QHR is used analyse measurements resistances both low- and sides sample. In addition, a bridge for contact sample presented. For first time, it now possible perform all whose dc equivalents are well established reliable measurements. While on high- low-potential very similar, interesting differences have observed at high...

We report new results and insights concerning the effect of side gates, back ac losses on properties quantum Hall resistance (QHR). Three different loss mechanisms have been identified, namely, dissipative in 2-D electron gas (2DEG), relaxation a surface layer above 2DEG, dielectric GaAs substrate. A novel shielding configuration reduces these makes QHR independent frequency current to better than 1 part 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML"...