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Search Results: 1 - 10 of 308574 matches for " D. F. Santavicca "
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Impedance-matched low-pass stripline filters
D. F. Santavicca,D. E. Prober
Physics , 2008, DOI: 10.1088/0957-0233/19/8/087001
Abstract: We have constructed several impedance-matched low-pass filters using a stripline geometry with a dissipative dielectric. The filters are compact, simple to construct, and operate in cryogenic environments. The dissipative dielectric consists of magnetically-loaded silicone or epoxy, which are commercially available under the trade name Eccosorb. For a stripline length of 32 mm, the filters have a passband that extends from dc to a 3 dB bandwidth between 0.3 and 0.8 GHz. The 3 dB bandwidth can be adjusted beyond this range by changing the filter length. An extremely broad stopband at higher frequencies, with attenuation exceeding 100 dB, is achieved along with a return loss greater than 10 dB measured up to 40 GHz. This combination of high attenuation and low reflected power across a broad stopband ensures that spurious or unwanted signals outside the passband do not reach or return to the device under test. This type of filter has applications in microwave frequency measurements of sensitive non-linear devices such as superconducting heterodyne mixers, quantum tunneling devices, and quantum computing elements.
Terahertz detection mechanism and contact capacitance of individual metallic single-walled carbon nanotubes
Joel D. Chudow,Daniel F. Santavicca,Chris B. McKitterick,Daniel E. Prober,Philip Kim
Physics , 2012, DOI: 10.1063/1.4704152
Abstract: We characterize the terahertz detection mechanism in antenna-coupled metallic single-walled carbon nanotubes. At low temperature, 4.2 K, a peak in the low-frequency differential resistance is observed at zero bias current due to non-Ohmic contacts. This electrical contact nonlinearity gives rise to the measured terahertz response. By modeling each nanotube contact as a nonlinear resistor in parallel with a capacitor, we determine an upper bound for the value of the contact capacitance that is smaller than previous experimental estimates. The small magnitude of this contact capacitance has favorable implications for the use of carbon nanotubes in high-frequency device applications.
Bolometric and non-bolometric radio frequency detection in a metallic single-walled carbon nanotube
Daniel F. Santavicca,Joel D. Chudow,Daniel E. Prober,Meninder S. Purewal,Philip Kim
Physics , 2011, DOI: 10.1063/1.3593500
Abstract: We characterize radio frequency detection in a high-quality metallic single-walled carbon nanotube. At a bath temperature of 77 K, only bolometric (thermal) detection is seen. At a bath temperature of 4.2 K and low bias current, the response is due instead to the electrical nonlinearity of the non-ohmic contacts. At higher bias currents, the contacts recover ohmic behavior and the observed response agrees well with the calculated bolometric responsivity. The bolometric response is expected to operate at terahertz frequencies, and we discuss some of the practical issues associated with developing high frequency detectors based on carbon nanotubes.
Energy loss of the electron system in individual single-walled carbon nanotubes
Daniel F. Santavicca,Joel D. Chudow,Daniel E. Prober,Meninder S. Purewal,Philip Kim
Physics , 2010, DOI: 10.1021/nl1025002
Abstract: We characterize the energy loss of the non-equilibrium electron system in individual metallic single-walled carbon nanotubes at low temperature. Using Johnson noise thermometry, we demonstrate that, for a nanotube with ohmic contacts, the dc resistance at finite bias current directly reflects the average electron temperature. This enables a straightforward determination of the thermal conductance associated with cooling of the nanotube electron system. In analyzing the temperature- and length-dependence of the thermal conductance, we consider contributions from acoustic phonon emission, optical phonon emission, and hot electron outdiffusion.
Niobium superconducting nanowire single-photon detectors
Anthony J. Annunziata,Daniel F. Santavicca,Joel D. Chudow,Luigi Frunzio,Michael J. Rooks,Aviad Frydman,Daniel E. Prober
Physics , 2009, DOI: 10.1109/TASC.2009.2018740
Abstract: We investigate the performance of superconducting nanowire photon detectors fabricated from ultra-thin Nb. A direct comparison is made between these detectors and similar nanowire detectors fabricated from NbN. We find that Nb detectors are significantly more susceptible than NbN to thermal instability (latching) at high bias. We show that the devices can be stabilized by reducing the input resistance of the readout. Nb detectors optimized in this way are shown to have approximately 2/3 the reset time of similar large-active-area NbN detectors of the same geometry, with approximately 6% detection efficiency for single photons at 470 nm.
Energy resolution of terahertz single-photon-sensitive bolometric detectors
D. F. Santavicca,B. Reulet,B. S. Karasik,S. V. Pereverzev,D. Olaya,M. E. Gershenson,L. Frunzio,D. E. Prober
Physics , 2009, DOI: 10.1063/1.3336008
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.
Proposal for a GHz count rate near-IR single-photon detector based on a nanoscale superconducting transition edge sensor
Daniel F. Santavicca,Faustin W. Carter,Daniel E. Prober
Physics , 2012, DOI: 10.1117/12.883979
Abstract: We describe a superconducting transition edge sensor based on a nanoscale niobium detector element. This device is predicted to be capable of energy-resolved near-IR single-photon detection with a GHz count rate. The increased speed and sensitivity of this device compared to traditional transition edge sensors result from the very small electronic heat capacity of the nanoscale detector element. In the present work, we calculate the predicted thermal response time and energy resolution. We also discuss approaches for achieving efficient optical coupling to the sub-wavelength detector element using a resonant near-IR antenna.
Hot Electron Bolometer Development for a Submillimeter Heterodyne Array Camera
Matthew O. Reese,Daniel F. Santavicca,Luigi Frunzio,Daniel E. Prober
Physics , 2006, DOI: 10.1109/TASC.2007.898195
Abstract: We are developing Nb diffusion-cooled Hot Electron Bolometers (HEBs) for a large-format array submillimeter camera. We have fabricated Nb HEBs using a new angle deposition process. We have characterized these devices using heterodyne mixing at 20 GHz. We also report on optimizations in the fabrication process that improve device performance.
Tunable superconducting nanoinductors
Anthony J Annunziata,Daniel F Santavicca,Luigi Frunzio,Gianluigi Catelani,Michael J Rooks,Aviad Frydman,Daniel E Prober
Physics , 2010, DOI: 10.1088/0957-4484/21/44/445202
Abstract: We characterize inductors fabricated from ultra-thin, approximately 100 nm wide strips of niobium (Nb) and niobium nitride (NbN). These nanowires have a large kinetic inductance in the superconducting state. The kinetic inductance scales linearly with the nanowire length, with a typical value of 1 nH/um for NbN and 44 pH/um for Nb at a temperature of 2.5 K. We measure the temperature and current dependence of the kinetic inductance and compare our results to theoretical predictions. We also simulate the self-resonant frequencies of these nanowires in a compact meander geometry. These nanowire inductive elements have applications in a variety of microwave frequency superconducting circuits.
Energy-resolved detection of single infrared photons with λ = 8 μm using a superconducting microbolometer
Boris S. Karasik,Sergey V. Pereverzev,Alexander Soibel,Daniel F. Santavicca,Daniel E. Prober,David Olaya,Michael E. Gershenson
Physics , 2012, DOI: 10.1063/1.4739839
Abstract: We report on the detection of single photons with {\lambda} = 8 {\mu}m using a superconducting hot-electron microbolometer. The sensing element is a titanium transition-edge sensor with a volume ~ 0.1 {\mu}m^3 fabricated on a silicon substrate. Poisson photon counting statistics including simultaneous detection of 3 photons was observed. The width of the photon-number peaks was 0.11 eV, 70% of the photon energy, at 50-100 mK. This achieved energy resolution is one of the best figures reported so far for superconducting devices. Such devices can be suitable for single photon calorimetric spectroscopy throughout the mid-infrared and even the far-infrared.
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