A5032358150- Advanced Electrical Measurement Techniques
- Physics of Superconductivity and Magnetism
- Quantum and electron transport phenomena
- Quantum Information and Cryptography
- Atomic and Subatomic Physics Research
- Quantum Computing Algorithms and Architecture
- Magnetic Properties and Applications
- Photonic and Optical Devices
- Surface and Thin Film Phenomena
- Power Quality and Harmonics
- Magneto-Optical Properties and Applications
- Superconducting and THz Device Technology
- Calibration and Measurement Techniques
- Advanced Frequency and Time Standards
- Advanced Sensor Technologies Research
- Advancements in Semiconductor Devices and Circuit Design
- Mechanical and Optical Resonators
- Scientific Measurement and Uncertainty Evaluation
- Iron-based superconductors research
- Semiconductor materials and devices
- Advanced Antenna and Metasurface Technologies
- Magnetic and transport properties of perovskites and related materials
- Seismic Waves and Analysis
- Particle physics theoretical and experimental studies
- Copper Interconnects and Reliability
Seoul National University
1994-2023
University of Twente
2023
Korea Advanced Nano Fab Center
2022-2023
X-Fab (Germany)
2023
Istituto Nazionale di Fisica Nucleare
2023
Nagoya University
2023
Institute of Electrical and Electronics Engineers
2023
Tufts University
2023
Sungkyunkwan University
2017-2023
University of Houston
2023
The Center for Axion and Precision Physics Research at the Institute Basic Science is searching axion dark matter using ultralow temperature microwave resonators. We report exclusion of mass range $10.7126--10.7186\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$ with near Kim-Shifman-Vainshtein-Zakharov (KSVZ) coupling sensitivity $10.16--11.37\text{ about 9 times larger 90% confidence level. This first search result in these ranges. It also a resonator physical less than 40 mK.
The resistance mechanisms of more than 2,000 aminoglycoside-resistant gram-negative aerobic bacteria were estimated by a method that assigned biochemical mechanism based on susceptibility to selected aminoglycosides. Strains from hospitals in Japan, Formosa, and Korea (the Far East) compared with strains Chile the United States. Of Chile, 90% had an aminoglycoside pattern indicative 3-N-acetyltransferase [AAC(3)-V] enzyme. East, 78% patterns suggesting presence AAC(6') enzymes. In contrast,...
We report an extensive high-sensitivity search for axion dark matter above 1 GHz at the Center Axion and Precision Physics Research (CAPP). The cavity resonant search, exploiting coupling between axions photons, explored frequency (mass) range of 1.025 (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mn>4.24</a:mn><a:mtext> </a:mtext><a:mtext> </a:mtext><a:mi mathvariant="normal">μ</a:mi><a:mi>eV</a:mi></a:mrow></a:math>) to 1.185 (<d:math...
Abstract Quantum computing devices are inevitably subject to errors. To leverage quantum technologies for computational benefits in practical applications, algorithms and protocols must be implemented reliably under noise imperfections. Since imperfections limit the size of circuits that can realized on a device, developing error mitigation techniques do not require extra qubits gates is critical importance. In this work, we present deep learning-based protocol reducing readout errors...
When a magnetic moment is embedded in metal, it captures itinerant electrons to form the Kondo cloud1,2, which can spread out over few micrometres3,4. For metal with dense impurities such that clouds overlap each other, correlated ground states are formed. regular lattice, result heavy fermion or anti-ferromagnetic order depending on dominant interaction5,6. Even case of random impurities, overlapping expected coherent state. Here, we examine this issue by performing electrical transport and...
We have developed vertically stacked superconductor normal-metal-superconductor Josephson junction technology for the next-generation quantum voltage standards. Stacked junctions provide a practical way of increasing output and operating margins. In this paper, we present fully functioning programmable standard chips with double- triple- MoSi/sub 2/ barrier over 100 000 simultaneously on 1 cm /spl times/ chip. The maximum voltages triple-stacked were 2.6 V 3.9 V, respective current margins 2...
We are implementing a new standard for 60 Hz power measurements based on precision sinusoidal reference voltages from two independent programmable Josephson voltage standards (PJVS): one and current. The National Institute of Standards Technology PJVS systems use series arrays junctions to produce accurate quantum-based DC voltages. Using stepwise-approximation synthesis, the sinewaves with precisely calculable RMS spectral content. present calculations that elucidate sources error in...
A waveform synthesizer adopting a superconductor–normal metal–superconductor junction array has been developed, which can generate arbitrary stepwise waveforms with number of quantum-voltage steps up to 1 V level amplitude. As an application the synthesizer, we have built sampling voltmeter that measures differential voltages between sinusoidal produced by semiconductor-based ac source and Josephson waveforms. We carried out extensive measurements for 50 Hz sine wave amplitude, applying...
We demonstrate that the superconducting critical temperature (Tc) of thin niobium films can be electrically modulated in a liquid-gated geometry device. Tc suppressed and enhanced by applying positive negative gate voltage, respectively, reversible manner within range about 0.1 K. At fixed below Tc, we observed current voltage. This result suggests possibility an controlled switching device operating at or above liquid helium temperature, where superconductivity turned on off solely applied
Recent advances in circuit design and fabrication of superconducting integrated circuits have enabled us to demonstrate an ac Josephson voltage standard (ACJVS) that generates both dc waveforms up 242-mV peak voltage. Using a Fast Fourier Transform spectrum analyzer ac-dc transfer standard, we characterize ACJVS operating margins by performing "flat-spot" measurements at the level part 10/sup 6/ for all eight bias parameters. By verifying every parameter has (i.e., range values over which...
We have developed a method of bonding superconductive integrated-circuit chips to interchangeable, microwave-compatible, flexible cryo-packages. This flip-chip on flex technology will greatly improve the service life and reliability our Josephson systems because present press-contacts chip are replaced with directly soldered connections. The new eliminates most common failure mode for chips, which has been degradation variation contact resistances pads due mechanical wear upon repeated...
We report on the fabrication and measurements of a superconducting junction single-crystalline Au nanowire, connected to Al electrodes. The current−voltage characteristic curve shows clear supercurrent branch below transition temperature quantized voltage plateaus application microwave radiation, as expected from Josephson relations. Highly transparent (0.95) contacts very close an ideal limit 1 are formed at interface between normal metal (Au) superconductor (Al). high transparency is...
This work presents a qubit controller IC based on the direct synthesis. The consists of six independently-working pulse modulators utilizing same LO frequency. We propose sinusoid-shaping nonlinear DAC followed by linear interpolating to improve both energy and hardware efficiencies. implemented in 40nm CMOS is verified superconducting operations with Rabi Ramsey oscillations while consuming power < 1/60 compared previous state-of-the-art.
NIST is using and developing superconductor-normal metal-superconductor (SNS) Josephson arrays for both programmable DC AC voltage standards. Increasing the output difficult because per junction small; hence series with large numbers of junctions are needed. The best way to generate higher voltages achieve operating margins broadband drive signals by densely packing into shorter arrays. has been working on stacked SNS this goal. By stacking in array, more may be placed length, while...
Dense, vertically stacked Josephson junction arrays are being developed for voltage metrology applications. We present measurements of the uniformity and reproducibility Nb/(MoSi2/Nb)N junctions that clarify superconducting properties middle Nb electrode. Middle electrode thicknesses down to 20 nm have shown minimal suppression order parameter as measured through critical current density. Even with a thickness 5 nm, excellent has been observed demonstrated by measurement large Shapiro steps...
The voltage from a single, microwave-biased Josephson junction is small quantity; thus useful voltages are generated only through series arrays of many thousands junctions. Arrays superconductor-normal metal-superconductor junctions have been fabricated and tested with as 16,500 per array. optimized for the highest operation largest operating margins current bias. Measurements show that these arrays, driven 20 GHz microwaves, generate dc greater than 680 mV array bias margin over 1 mA. To...
We present a detailed study of the electrical properties planar Nb–MoSi2–Nb Josephson junctions. The junction is an excellent system to proximity coupling in junctions with rigid superconductor/normal metal boundaries by precisely and independently controlling barrier thickness temperature. With regard applications, are very reproducible, characteristic voltage can be tuned easily over more than two orders magnitude while still maintaining practical critical current density. controlled...
We report an extensive high-sensitivity search for axion dark matter above 1\,GHz at the Center Axion and Precision Physics Research (CAPP). The cavity resonant search, exploiting coupling between axions photons, explored frequency (mass) range of 1.025\,GHz (4.24\,$\mu$eV) to 1.185\,GHz (4.91\,$\mu$eV). have introduced a number innovations in this field, demonstrating practical approach optimizing all relevant parameters haloscopes, extending presently available technology. CAPP 12\,T...
Nb/MoSi 2 / Nb stacked superconductor–normal metal–superconductor (SNS) Josephson junctions has proven to be a good candidate for high-density series arrays voltage-standard applications. As the junction density increases, self-heating becomes an issue because high power per (1 W/cm2) generates significant dissipation under typical operating conditions. In this letter, we analyze heating effect of these sandwich-type SNS using model quantitatively estimate and predict thermal-transport...
Superconductor-normal metal-superconductor (SNS) Josephson junctions have proven to be a critical technology for voltage standards. NIST has used SNS both dc and ac programmable Previous devices primarily PdAu as normal-metal barrier material. In this paper we present measurements of circuits having MoSi/sub 2/ barriers. Stacking enables the packed more densely, thus increasing design flexibility margins microwave circuits. work, are presented from two- three-junction stacks application...
The authors have made tall, uniform stacked Josephson junction arrays by developing an etch process using inductively coupled plasma etcher. This produces vertical profiles in thin-film multilayers of alternating superconducting and normal metals. Such a is necessary to obtain properties high-density order achieve operating margins for voltage-standard applications. use dry-etchable MoSi/sub 2/ the metal barrier our niobium junctions working series with stacks up 10 tall. present dc...
We present a detailed study of the electrical properties Nb-based planar Josephson junctions with superconducting metal silicide barriers, TiSi2 and WSi2. While these nonhysteretic are useful for voltage standard applications, they also an excellent model system to proximity coupling in having barrier finite transition temperature. These silicide-barrier have uniformity controllability, but as opposed junction barriers no measurable transition, critical current superconducting-barrier is...
Using a new circuit design and double-stacked junction technology we have demonstrated fully functional high-resolution programmable voltage standard chips with 67 410 junctions that operate up to maximum output of 2.6 V. The uses junctions, where two are fabricated in each stack, order increase the voltage. We also improved resolution at fixed frequencies 16-fold by using optimized for three states 128-fold below 2 V oppositely biasing large arrays whose counts differ single stack. These...