Bulletin of the American Physical Society
APS March Meeting 2010
Volume 55, Number 2
Monday–Friday, March 15–19, 2010; Portland, Oregon
Session T29: Superconducting Devices and Applications |
Hide Abstracts |
Sponsoring Units: FIAP DCMP Chair: Fred Wellstood, University of Maryland Room: C123 |
Wednesday, March 17, 2010 2:30PM - 2:42PM |
T29.00001: Ultra-Small Superconducting RF Metamaterials Cihan Kurter, Steven M. Anlage We propose an ultra-compact design for RF metamaterials implemented with Nb thin films. Those miniaturized devices are fashioned in the form of planar spirals operating at frequencies below 100 MHz, where existing normal-metal metamaterials are quite lossy. The transmission data have shown robust resonance peaks below the superconducting transition temperature (Tc) of Nb which are sensitively tunable with temperature and RF power, and no resonant features above Tc. We discuss the advantages and intrinsic aspects of using superconductors in constructing RF metamaterials such as adding kinetic/Josephson inductance and nonlinearity into their resonance modes. [Preview Abstract] |
Wednesday, March 17, 2010 2:42PM - 2:54PM |
T29.00002: Thermal relaxation and kinetic inductance in superconducting nanowires used as single photon detectors Anthony Annunziata, Daniel Santavicca, Joel Chudow, Orlando Quranta, Luigi Frunzio, Aviad Frydman, Michael Rooks, Daniel Prober As many groups have shown, superconducting nanowires can be used as high count rate single-photon detectors for visible and infrared photons. We study thermal relaxation in Nb nanowires following the absorption of a single-photon using a combination of experiments and numerical modeling. Experiments for Nb agree well with numerical predictions. We compare these results to measurements of NbN nanowires by us as well as other groups. Our studies highlight the roles of the different material and readout-circuit parameters. Our model suggests that in Nb, slow thermal relaxation of the electron system significantly limits the detector reset time. We also study the temperature and bias current dependence of the kinetic inductance of NbN nanowires over a large range of current and temperature. We find that the current dependence deviates significantly from what is expected from the Ginzburg-Landau theory even when measured close to the critical temperature. This work is supported by NSF - EPDT, NSF -- Graduate Research Fellowship, and IBM research. [Preview Abstract] |
Wednesday, March 17, 2010 2:54PM - 3:06PM |
T29.00003: Dissipative effects and GHz amplification with superconducting Fabry-Perot resonators coupled to nanowires Matthew Brenner, Sarang Gopalakrishnan, Jaseung Ku, Nayana Shah, Paul Goldbart, Alexey Bezryadin Superconducting nanowires embedded in microwave Fabry-Perot resonators exhibit nonlinear and dissipative phenomena when the cavity is driven at sufficiently high power. These phenomena arise when the a.c.~current in the resonator exceeds the nanowire's depairing current. The behavior includes the appearance of (1)~a local minimum in the transmitted intensity at the resonance frequency (i.e., a ``crater''), (2)~dissipative bi-stability and hysteresis as the input frequency is swept across the resonance, and (3)~a periodic array of transmission maxima at frequencies offset from the input frequency. When a superposition of two signals is applied, with the stronger pump signal residing in the crater, a narrowband amplification (+24.0 dB) of the weaker signal is observed. The frequency of the amplification band can be controlled by adjusting the pump power. We demonstrate the existence of these effects in MoGe and Nb nanowires and develop a phenomenological model to describe them [Preview Abstract] |
Wednesday, March 17, 2010 3:06PM - 3:18PM |
T29.00004: Transport Characteristics of Superconductor-based Light-Emitting-Diode Structure Ryotaro Inoue, Hideaki Takayanagi, Tatsushi Akazaki, Kazunori Tanaka, Hirotaka Sasakura, Ikuro Suemune We investigated the transport characteristics between two niobium (Nb) superconducting electrodes at the n-type semiconductor (n- InGaAs) side of a superconductor-based Light-Emitting-Diode where a Josephson junction is formed. The current-voltage characteristics of the Josephson junction are found to be controlled by applying voltage to the normal electrode at the p-type semiconductor (p-InP) side. The mechanism of the control is switched from gate regime to injection regime when the applied voltage is increased and current injection takes place. At the crossover region between two regimes, the current-voltage characteristics of the Josephson junction show an extraordinary sensitivity to the applied voltage to the normal electrode at the p-type semiconductor. This sensitivity is considered to be due to the radiative recombination process at the superconductor-based Light-Emitting Diode. [Preview Abstract] |
Wednesday, March 17, 2010 3:18PM - 3:30PM |
T29.00005: The dynamical Casimir effect in a superconducting coplanar waveguide J. Robert Johansson, G\"{o}ran Johansson, Chris Wilson, Franco Nori We investigate the dynamical Casimir effect in a coplanar waveguide (CPW) terminated by a superconducting quantum interference device (SQUID). Changing the magnetic flux through the SQUID parametrically modulates the boundary condition of the CPW, and thereby, its effective length. Effective boundary velocities comparable to the speed of light in the CPW result in broadband photon generation which is identical to the one calculated in the dynamical Casimir effect for a single oscillating mirror. We estimate the power of the radiation for realistic parameters and show that it is experimentally feasible to directly detect this nonclassical broadband radiation. \\[4pt] Phys. Rev. Lett. 103, 147003 (2009) [Preview Abstract] |
Wednesday, March 17, 2010 3:30PM - 3:42PM |
T29.00006: THz antenna-coupled nanoscale electron-phonon bolometers Christopher McKenney, Andrew Cleland We are fabricating nanoscale bolometers for use in THz radiation detection. A sufficiently small volume of normal metal volume is so decoupled from phonons at mK temperatures that thermal time constants can reach milliseconds. We sense the temperature change in the electron gas due to THz radiation absorption using a pair of superconductor-insulator-normal metal (SIN) tunnel junctions, probed using a radiofrequency tank circuit to achieve large measurement bandwidth. THz radiation is coupled to the normal metal with an impedance-matched double slotline antenna; we use a blackbody source to generate photons at $\sim $ 1 THz. We report our progress on the development of these devices. [Preview Abstract] |
Wednesday, March 17, 2010 3:42PM - 3:54PM |
T29.00007: Numerical Simulations of Two-Dimensional Arrays of Superconducting Quantum Interference Devices Steven Anton, Shane Cybart, Stephen Wu, John Clarke, R. C. Dynes We present a numerical model that simulates the voltage versus applied magnetic field ($V$-$B$) characteristics of a serial- parallel superconducting quantum interference device (SQUID) array. Our model incorporates resistively shunted Josephson junctions with inhomogeneous parameters as well as non- negligible loop inductances to solve self-consistently the Josephson relations for each junction in the array. Currents through the array are not artificially constrained, thus allowing the possibility of complex percolation paths. The model also allows one to monitor quantities that are difficult to observe experimentally, such as the time dependent current distributions, magnetic fluxes, and junction phase information within the array. In addition, time dependent bias currents and magnetic fields are easily incorporated into the simulation. We compare simulation $V$-$B$ characteristics to recently- reported experimental data of large scale SQUID arrays with several complex area distributions. We find good agreement between simulation and experiment in arrays where the number of SQUIDs in parallel is not too large. [Preview Abstract] |
Wednesday, March 17, 2010 3:54PM - 4:06PM |
T29.00008: Noise of the lumped-element DC-SQUID microwave amplifier Lafe Spietz, Minhyea Lee, Jos\'{e} Aumentado We present measurements of the noise characteristics a microwave amplifier based on a DC-SQUID in a lumped element configuration. We describe measurements using both a heated load and a normal metal tunnel junction shot noise source. We use this information to describe the behavior of the noise both from the perspective of understanding the SQUID and from the perspective of developing a method for most effectively using these amplifiers in practical experiments. We show that the SQUID amplifier can improve system noise temperature by an order of magnitude over HEMT-based systems in the 4-8 GHz frequency range. [Preview Abstract] |
Wednesday, March 17, 2010 4:06PM - 4:18PM |
T29.00009: Shot noise tunnel junctions for calibrating amplifier Minhyea Lee, Lafe Spietz, Jos\'{e} Aumentado We present the application of shot noise tunnel junction (SNTJ) made of Al/AlO$_{x}$/Al for calibrating microwave amplifiers. Junctions are fabricated via double angle deposition. Oxidization condition for the junction is carefully determined in such way that the characteristic impedance is about 50 ohm with less than -15 dB of return loss up to 8 GHz. In comparison with conventional Y-factor measurement, we can improve the speed and accuracy tremendously in obtaining gain and noise temperature at various temperatures, by taking advantage of the self-calibrating nature of SNTJ. We demonstrate the calibrations of different kind of microwave amplifiers with this broad band noise source and will discuss its merits in practice. [Preview Abstract] |
Wednesday, March 17, 2010 4:18PM - 4:30PM |
T29.00010: High field on-chip SQUID measurement of spin quantum tunneling Lei Chen, Wolfgang Wernsdorfer, Irinel Chiorescu Experiments involving quantum spins [1] show that localized spins are candidates for implementation of quantum algorithms, but sensitive on-chip spin detection needs to be developed. In our setup at NHMFL, we placed a small magnetic sample in the vicinity of an on-chip Nb SQUID, and applied a magnetic field precisely parallel to SQUID plane. With SQUIDs only few nm thick, we can perform measurements in fields as high as 7 T, which is desirable to study a larger family of molecular magnets or diluted spin system. Landau-Zener quantum tunneling [2] in swept magnetic field reveals spin Hamiltonian information, like the anisotropy-induced tunneling gaps and entanglement of spin states. Successful SQUID measurements of the quantum tunneling of spins, in the presence of fields up to 5.5T, will be presented. 1. S. Bertaina \textit{et al}, Nature \textbf{453}, 203 (2008); S. Nellutla \textit{et al}, PRL. \textbf{99}, 137601 (2007); S. Bertaina \textit{et al}, PRL \textbf{102}, 050501 (2009) 2. W. Wernsdorfer \textit{et al}, EPL \textbf{5}, 552 (2000); L. Chen \textit{et al}, EPL \textbf{87,} 57010 (2009) [Preview Abstract] |
Wednesday, March 17, 2010 4:30PM - 4:42PM |
T29.00011: Measurement of the nonlinear Meissner effect (NLME) with an on-chip cavity Nickolas Groll, Alex Gurevich, Irinel Chiorescu Meissner effect is one of the fundamental manifestations of the macroscopic phase coherence of a superconducting (SC) state. At high fields, the superfluid density is dependent on the velocity of the condensate resulting in the NLME [1,2]. We report observation of the NLME in Nb films by measuring the resonance frequency of a planar SC cavity as a function of the magnitude and the orientation of a parallel magnetic field [3]. Using low power rf probing in films thinner than the London penetration depth, significantly increases the field for the vortex penetration onset and enables NLME detection under true equilibrium conditions. The data agrees very well with calculations based on the Usadel equations. We propose to use NLME angular spectroscopy to probe unconventional pairing symmetries in superconductors. \\[4pt] [1] S.K. Yip and J.A. Sauls, \textit{PRL} 69, 2264 (1992) \\[0pt] [2] R. Prozorov and R.W. Giannetta, \textit{Supercond. Sci. Technol}. \textbf{19}, R41 (2006). \\[0pt] [3] N. Groll, A. Gurevich, I. Chiorescu, \textit{submitted}, arXiv:908.4097 [Preview Abstract] |
Wednesday, March 17, 2010 4:42PM - 4:54PM |
T29.00012: Quantifying Entanglement with a Joint Readout of Superconducting Qubits Jerry Chow, Leonardo DiCarlo, Jay Gambetta, Andreas Nunnenkamp, Lev Bishop, Luigi Frunzio, Michel Devoret, Steven Girvin, Robert Schoelkopf We employ a single channel as a joint readout of highly-entangled two-qubit states in a circuit quantum electrodynamics architecture. The measurement model for the readout is fully characterized using a set of Rabi experiments demonstrating a large sensitivity to two-qubit correlations. We quantify the high degree of entanglement by measuring the violation of a Clauser-Horne-Shimony-Holt inequality with a value of $2.61\pm0.04$, without any optimization for the target state. In its present form, this joint readout will be capable of resolving improvements to the fidelity of two-qubit operations and will be extendable to systems of three or four qubits. [Preview Abstract] |
Wednesday, March 17, 2010 4:54PM - 5:06PM |
T29.00013: Quantum regime dielectric loss studies of bulk substrates with a high-Q superconducting cavity Hanhee Paik, Luigi Frunzio, Robert Schoelkopf Recent measurements of transmission-line resonators and superconducting qubits have demonstrated that dielectric films can have anomalous losses which increase in the single photon regime [1]. Bulk substrate materials such as single-crystal sapphire have been shown to have much smaller losses in many- photon experiments, but there have not been detailed measurements of these materials in the single-photon limit. We present measurements of dielectric loss in single crystal wafers in this limit using the cavity perturbation technique at 20 mK. We employ a three-dimensional superconducting resonant cavity whose quality factor is higher than 10$^6$. Results on various materials such as sapphire and high-resistivity silicon will be compared. [1] A. D. O'Connell, et al. Appl. Phys. Lett. 92, 112903 (2008) [Preview Abstract] |
Wednesday, March 17, 2010 5:06PM - 5:18PM |
T29.00014: Latching behavior of the driven damped Jaynes-Cummings model in circuit-QED Lev Bishop, Eran Ginossar, David Schuster, Steven Girvin For superconducting circuits, typical latching behavior occurs in a quasi-classical fashion in weakly nonlinear systems, for example: the Josephson Bifurcation Amplifier. In contrast we investigate the situation where latching is provided by the strong intrinsic non-linearity of a qubit in the strong-coupling vacuum Rabi regime of circuit QED. In this context we use quantum simulations to gain access to the intermediate regime between the single photon-blockade and quasi-harmonic limits of a qubit-cavity system. We study the dynamical properties (lifetime, basin of attraction) of excited non-equilibrium states of the Jaynes-Cummings model. We expect that this scheme will be useful for qubit readout with experimental realizations of transmon qubits. [Preview Abstract] |
Wednesday, March 17, 2010 5:18PM - 5:30PM |
T29.00015: Proposal for application of coherent control to qubit readout in circuit QED Eran Ginossar, Lev Bishop, David Schuster, Steven Girvin High fidelity readout of superconducting qubits in circuit-QED requires effective protocols for mapping the 0,1 computational basis states onto macroscopically distinguishable states of the system. We explore the possibility of conditionally steering the system from the computational basis into quasi-coherent latching states of the Jaynes-Cummings Hamiltonian. We discuss the applicability of methods inspired by quantum optics and quantum control theory to this problem, based on realistic physical considerations pertaining to the transmon superconducting qubit. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700