5 results on '"Daniel F. Santavicca"'
Search Results
2. A distributed electrical model for superconducting nanowire single photon detectors
- Author
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Daniel F. Santavicca, Qing-Yuan Zhao, Di Zhu, Brian Noble, and Karl K. Berggren
- Subjects
Photon ,Physics and Astronomy (miscellaneous) ,Impedance matching ,Nanowire ,FOS: Physical sciences ,Physics::Optics ,Superconducting nanowire single-photon detector ,Applied Physics (physics.app-ph) ,02 engineering and technology ,01 natural sciences ,Kinetic inductance ,law.invention ,Condensed Matter::Materials Science ,law ,Transmission line ,0103 physical sciences ,010306 general physics ,Physics ,business.industry ,Coplanar waveguide ,Physics - Applied Physics ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,Optoelectronics ,Resistor ,0210 nano-technology ,business - Abstract
© 2018 Author(s). To analyze the switching dynamics and output performance of a superconducting nanowire single photon detector (SNSPD), the nanowire is usually modelled as an inductor in series with a time-varying resistor induced by the absorption of a photon. Our recent experimental results show that, due to the effect of kinetic inductance, for a SNSPD made of a nanowire of sufficient length, its geometrical length can be comparable to or even longer than the effective wavelength of frequencies contained in the output pulse. In other words, a superconducting nanowire can behave as a distributed transmission line so that the readout pulse depends on the photon detection location and the transmission line properties of the nanowire. Here, we develop a distributed model for a superconducting nanowire and apply it to simulate the output performance of a long nanowire designed into a coplanar waveguide. We compare this coplanar waveguide geometry to a conventional meander nanowire geometry. The simulation results agree well with our experimental observations. With this distributed model, we discuss the importance of microwave design of a nanowire and how impedance matching can affect the output pulse shape. We also discuss how the distributed model affects the growth and decay of the photon-triggered resistive hotspot.
- Published
- 2018
3. Microwave dynamics of high aspect ratio superconducting nanowires studied using self-resonance
- Author
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Daniel F. Santavicca, Jesse K. Adams, Adam N. McCaughan, Karl K. Berggren, Lierd E. Grant, Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science, McCaughan, Adam N, and Berggren, Karl K
- Subjects
Materials science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed matter physics ,Condensed Matter - Superconductivity ,Coplanar waveguide ,Nanowire ,FOS: Physical sciences ,Physics::Optics ,General Physics and Astronomy ,Resonance ,02 engineering and technology ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,01 natural sciences ,Kinetic inductance ,Superconductivity (cond-mat.supr-con) ,Inductance ,Condensed Matter::Materials Science ,Transmission line ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,Transmission coefficient ,010306 general physics ,0210 nano-technology ,Electrical impedance - Abstract
We study the microwave impedance of extremely high aspect ratio (length/width ≈ 5000) superconducting niobium nitride nanowires. The nanowires are fabricated in a compact meander geometry that is in series with the center conductor of a 50 Ω coplanar waveguide transmission line. The transmission coefficient of the sample is measured up to 20 GHz. At high frequency, a peak in the transmission coefficient is seen. Numerical simulations show that this is a half-wave resonance along the length of the nanowire, where the nanowire acts as a high impedance, slow wave transmission line. This resonance sets the upper frequency limit for these nanowires as inductive elements. Fitting simulations to the measured resonance enables a precise determination of the nanowire's complex sheet impedance at the resonance frequency. The real part is a measure of dissipation, while the imaginary part is dominated by kinetic inductance. We characterize the dependence of the sheet resistance and sheet inductance on both temperature and current and compare the results to recent theoretical predictions for disordered superconductors. These results can aid in the understanding of high frequency devices based on superconducting nanowires. They may also lead to the development of novel superconducting devices such as ultra-compact resonators and slow-wave structures., National Science Foundation (U.S.) (grant CCS‐1509253 (UNF)), National Science Foundation (U.S.) (grant ECCS‐1509486 (MIT)), Research Corporation for Science Advancement (Cottrell College Science Award)
- Published
- 2016
4. Efficient measurement of broadband terahertz optical activity
- Author
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Daniel F. Santavicca, Daniel J. Aschaffenburg, Michael R. C. Williams, Daniel E. Prober, Charles A. Schmuttenmaer, and Diyar Talbayev
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Spectrum analyzer ,Materials science ,Physics and Astronomy (miscellaneous) ,Terahertz radiation ,business.industry ,Detector ,Physics::Optics ,Spectral component ,Terahertz spectroscopy and technology ,Photomixing ,symbols.namesake ,Optics ,Broadband ,symbols ,Stokes parameters ,business - Abstract
We report a method to determine the four Stokes parameters of each spectral component in a broadband terahertz (THz) pulse by using a continuously rotating analyzer and a standard THz time domain spectroscopy (THz-TDS) instrument. A complete characterization of the polarization state at each frequency is obtained through a single time-domain measurement. Our method requires no specialized THz emitters or detectors; it is, therefore, perfectly general and suitable for any existing THz-TDS apparatus.
- Published
- 2012
5. Energy resolution of terahertz single-photon-sensitive bolometric detectors
- Author
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Daniel F. Santavicca, Sergei V. Pereverzev, Luigi Frunzio, Boris S. Karasik, David Olaya, Michael Gershenson, Bertrand Reulet, and Daniel E. Prober
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Physics ,Superconductivity ,Physics - Instrumentation and Detectors ,Photon ,Physics and Astronomy (miscellaneous) ,business.industry ,Terahertz radiation ,Condensed Matter - Superconductivity ,Bolometer ,FOS: Physical sciences ,Photodetector ,Instrumentation and Detectors (physics.ins-det) ,Photon energy ,Noise (electronics) ,law.invention ,Superconductivity (cond-mat.supr-con) ,Optics ,law ,business ,Microwave - Abstract
We report measurements of the energy resolution of ultra-sensitive superconducting bolometric detectors. The device is a superconducting titanium nanobridge with niobium contacts. A fast microwave pulse is used to simulate a single higher-frequency photon, where the absorbed energy of the pulse is equal to the photon energy. This technique allows precise calibration of the input coupling and avoids problems with unwanted background photons. Present devices have an intrinsic full-width at half-maximum energy resolution of approximately 23 terahertz, near the predicted value due to intrinsic thermal fluctuation noise., Comment: 11 pages (double-spaced), 5 figures; minor revisions
- Published
- 2010
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