http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Niemeyer J. (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
-
Fundamental Metrology by Counting Single Flux and Single Charge Quanta with Superconducting Circuits
Niemeyer, J. The Korean Superconductivity Society 2002 Progress in superconductivity Vol.4 No.1
Transferring single flux quanta across a Josephson junction at an exactly determined rate has made highly precise voltage measurements possible. Making use of self-shunted Nb-based SINIS junctions, programmable fast-switching DC voltage standards with output voltages of up to 10 V were produced. This development is now extended from fundamental DC measurements to the precise determination of AC voltages with arbitrary waveforms. Integrated RSFQ circuits will help to replace expensive semiconductor devices for frequency control and signal coding. Easy-to-handle AC and inexpensive quantum voltmeters of fundamental accuracy would be of interest to industry. In analogy to the development in the flux regime, metallic nanocircuits comprising small-area tunnel junctions and providing the coherent transport of single electrons might play an important role in quantum current metrology. By precise counting of single charges these circuits allow prototypes of quantum standards for electric current and capacitance to be realised. Replacing single electron devices by single Cooper pair circuits, the charge transfer rates and thus the quantum currents could be significantly increased. Recently, the principles of the gate-controlled transfer of individual Cooper pairs in superconducting A1 devices in different electromagnetic environments were demonstrated. The characteristics of these quantum coherent circuits can be improved by replacing the small aluminum tunnel Junctions by niobium junctions. Due to the higher value of the superconducting energy gap ($\Delta_{Nb}$ = $7\Delta_{Al}$), the characteristic energy and the frequency scales for Nb devices are substantially extended as compared to A1 devices. Although the fabrication of small Nb junctions presents a real challenge, the Nb-based metrological devices will be faster and more accurate in operation. Moreover, the Nb-based Cooper pair electrometer could be coupled to an Nb single Cooper pair qubit which can be beneficial for both, the stability of the qubit and its readout with a large signal-to-noise ratio..
-
Stabilization of Magnet Current Using Voltage Standards
Kim, K.-T.,Kim, M.-S.,Park, P.G.,Niemeyer, J. IEEE 2005 IEEE transactions on magnetics Vol.41 No.10
A stable high current source is frequently used for various magnetic metrology applications such as magnetic field generation for <TEX>$gamma'_ p$</TEX> , measurement and for testing various magnetic sensors. As a current stabilization method, a feedback scheme based on a voltage reference was previously suggested. We tested the feedback method for 1 A solenoid current using Zener voltage standard, and attained stability of <TEX>$2times10^-8$</TEX> . Comparing the result with previous one using programmable Josephson voltage standard, we found the limitation of the attained stability is mainly from the feedback scheme, not from the stability of voltage reference. The 1 A is magnitude of the SI ampere (A), and current at which the <TEX>$gamma_ p'$</TEX> measurement is carried out.
-
Kim, Kyu-Tae,Kim, Mun-Seog,Kim, Myungsoo,Niemeyer, J. IEEE 2005 IEEE transactions on instrumentation and measureme Vol.54 No.2
A stable reference source with a high current capability is useful for many metrological applications. Unlike the conventional Josephson voltage standard, one can couple the programmable Josephson voltage standard (PJVS) to a current source below milliamp range to stabilize the current. For higher current ranges, we tested a feedback method which allowed us to stabilize the 0.1-A output current of a commercial current source to within a standard deviation of 2 × 10<SUP>-8</SUP> A/A.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
