Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session Y38: Superconductivity: Josephson Effect/THz/ Microwave |
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Sponsoring Units: DCMP Chair: Timir Datta, University of South Carolina Room: 385 |
Friday, March 17, 2017 11:15AM - 11:27AM |
Y38.00001: Microwave resonant activation in hybrid single-gap/two-gap Josephson tunnel junctions Roberto Ramos, Steven Carabello, Joseph Lambert, Jerome Mlack, Wenqing Dai, Qi Li, Ke Chen, Daniel Cunnane, Xiaoxing Xi Microwave resonant activation is a powerful technique to study classical and quantum systems, experimentally realized in Josephson junctions. We have recently reported the first demonstration of resonant activation experiments on hybrid, thin film Josephson heterojunctions consisting of a multi-gap superconductor (MgB2) separated from a single-gap superconductor (Pb or Sn) by an insulating barrier [1]. In this presentation, we expound on several quantum signatures exhibited in superconducting-to-normal state switching in these devices, including a leveling off of the Tesc vs. T curve and Lorentzian peaks in the escape rate enhancement. We also discuss features which are commonly ascribed to multi-photon transitions between quantum levels inside a junction, and the implications of these. References: 1. S.Carabello, et. al., J. Appl. Phys. 120, 123904 (2016) [Preview Abstract] |
Friday, March 17, 2017 11:27AM - 11:39AM |
Y38.00002: Terahertz emission from pie-shaped wedge microstrip antennas of the high-$T_c$ superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ Qing Wang, Constance Doty, Richard Klemm, Kaveh Delfanazari, Daniel Cerkoney, Takashi Yamamoto, Manabu Tsujimoto, Kazuo Kadowaki, Chiharu Watanabe, Hidetoshi Minami, Takanari Kashiwagi, Manuel Morales We calculate the standing wave functions for pie-shaped wedge microstrip antennas of various wedge angles $\phi_0$. We then calculate the emission distributions from the uniform Josephson current and from the excitation of a cavity mode generated from the stand wave functions. For a narrow dieter's pie slice, quantitative fits to the experimental data on a Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ narrow isosceles triangular mesa are shown. [Preview Abstract] |
Friday, March 17, 2017 11:39AM - 11:51AM |
Y38.00003: Two Dimensional Wireless Josephson Junction Arrays: A Microwave Transmission Investigation Laura Adams We investigate the flow of Cooper pairs and unpaired electrons though an unbiased ordered 2D lattice of superconductor-insulator-superconductor tunnel junctions in the presence of an AC microwave field. The transmission reveals a robust resonance at temperatures below the transition temperature,T$_c$, and at low microwave power. As power is increased at fixed temperature, below T$_c$, resonant peaks split into two. In aggregate, these split peaks show well defined frequency steps for a range of temperatures. We review this data from various viewpoints, including the Berezinskii-Kosterlitz-Thouless phase transition, Shapiro steps, and as an 'artificial' supersolid. We gratefully acknowledge Professors Steven Anlage and Allen Goldman’s support. [Preview Abstract] |
Friday, March 17, 2017 11:51AM - 12:03PM |
Y38.00004: Microwave spectra of Andreev levels in nanowire Josephson junctions Attila Geresdi, David J. van Woerkom, Alex Proutski, Bernard van Heck, Daniel Bouman, Jukka I. Vayrynen, Leonid I. Glazman, Peter Krogstrup, Jesper Nygard, Leo P. Kouwenhoven Narrow gap semiconductors, such as InAs and InSb have recently become the most studied platform of Majorana zero modes and novel superconducting qubit architectures. The microscopic description of the superconducting proximity effect however requires the understanding of the Andreev bound state spectrum in these systems. Here we present our experimental work addressing the Andreev levels in Josephson junctions of InAs nanowires with aluminum epitaxial shells. In order to directly access the excited Andreev levels up to 90 GHz bounded by the gap of aluminum, we utilize inelastic Cooper-pair tunneling in an on-chip coupled superconducting tunnel junction. With this technique, we show the presence of gate-tunable Andreev levels in a ballistic semiconductor channel for the first time, and demonstrate how an external applied magnetic field influences the spectrum in the presence of strong spin-orbit coupling, relevant for parity-controlled investigations of Majorana bound states. The accompanying theory work is presented by B. van Heck. Reference: D.J van Woerkom et al, arXiv:1609.00333 [Preview Abstract] |
Friday, March 17, 2017 12:03PM - 12:15PM |
Y38.00005: Theory of microwave spectra of Andreev levels in nanowire Josephson junctions Bernard Van Heck, Jukka I. Vayrynen, Leonid I. Glazman, David J. van Woerkom, Alex Proutski, Daniel Bouman, Peter Krogstrup, Jesper Nygard, Leo P. Kouwenhoven, Attila Geresdi We find the energy spectrum and the electromagnetic response of Andreev bound states in Josephson junctions made of semiconducting nanowires. We focus on the joint effect of Zeeman and spin-orbit coupling on the Andreev level spectra. Our model incorporates the penetration of the magnetic field in the proximitized wires, which substantially modifies the spectra. We pay special attention to the occurrence of fermion parity switches at increasing values of the field, and to the repulsion of the Andreev levels from the quasiparticle continuum. These theoretical considerations are applied to the analysis of recent experimental results on the microwave spectroscopy of InAs/Al Josephson junctions (D. J. van Woerkom et al., arXiv:1609.00333), complementing the talk of A. Geresdi on the same work. [Preview Abstract] |
Friday, March 17, 2017 12:15PM - 12:27PM |
Y38.00006: Ultrasensitive Electrometry with a Cavity-Embedded Cooper Pair Transistor A. J. Rimberg, JULIANG LI In this experiment a cavity-embedded Cooper-pair transistor (cCPT) is used as a potentially quantum-limited electrometer. The cCPT consists of a Cooper pair transistor placed at the voltage antinode of a 5.7 GHz shorted quarter-wave resonator so that the CPT provides a galvanic connection between the cavity's central conductor and ground plane. The quantum inductance of the CPT, which appears in parallel with the effective inductance of the cavity resonance, can be modulated by application of either a gate voltage to the CPT island or a flux bias to the CPT/cavity loop. Changes in the CPT inductance shift the cavity resonant frequency, and therefore the phase of a microwave signal reflected from the cavity. The reflected wave is amplified by both SLUG[1] and HEMT amplifiers before its phase is measured. The cCPT can also be operated as a Josephson parametric amplifier (JPA). A pump tone at 11.4 GHz sent into the flux bias line has been shown to provide about 10dB gain. The possibility of parametrically amplifying the side bands produced by a charge detection measurement, thereby increasing the overall sensitivity of the cCPT, will also be investigated. 1. Hover, et al. Appl. Phys. Lett. {\bfseries 100}, 063503 (2012). [Preview Abstract] |
Friday, March 17, 2017 12:27PM - 12:39PM |
Y38.00007: Josephson Parametric Amplifer Based on a Cavity-Embedded Cooper Pair Transistor Juliang Li, A. J. Rimberg In this experiment a cavity-embedded Cooper-pair transistor (cCPT) is used as a Josephson parametric amplifier. The cCPT consists of a Cooper pair transistor placed at the voltage antinode of a 5.7 GHz shorted quarter-wave resonator so that the CPT provides a galvanic connection between the cavity's central conductor and ground plane, which forms a SQUID loop. Both the flux threading the loop as well as the gate charge can be modulated, and each can provide the parametric pumping. The reflected signal from the cCPT is further amplified by both SLUG[1] and HEMT amplifiers for characterizing the parametric amplification. A first application of the parametric amplification is to improve the charge sensitivity of a single electron charge detector. This can be done either by pumping on a side band or by shifting the charge state of the cCPT near a bifurcation point. Stimulated emission has been also observed when the cCPT is pumped at twice the resonant frequency in the absence of an input signal. This could allow investigation of the dynamic Casimir effect as well as generation of non-classical photon states. 1. Hover, et al, Appl. Phys. Lett. {\bseries 100}, 063503 (2012) [Preview Abstract] |
Friday, March 17, 2017 12:39PM - 12:51PM |
Y38.00008: Effect of stripline electrodes on coherent terahertz emission from BSCCO intrinsic Josephson junctions Manabu Tsujimoto, Genki Kuwano, Chiharu Watanabe, Hiroyuki Kubo, Kazuki Sakamoto, Takuya Katsuragawa, Taiga Tanaka, Takumi Yuasa, Yuki Komori, Ryusei Ota, Yuuki Tanabe, Kento Nakamura, Takanari Kashiwagi, Hidetoshi Minami, Kazuo Kadowaki, Takuji Doi, Asem Elarabi, Itsuhiro Kakeya Since terahertz radiation in the 0.3--10 THz frequency range is technologically attractive, terahertz generation from stacks of intrinsic Josephson junctions in Bi$_{\mathrm{2}}$Sr$_{\mathrm{2}}$CaCu$_{\mathrm{2}}$O$_{\mathrm{8+\delta }}$ (Bi-2212) has become a major focus of both experimental and theoretical research [U. Welp \textit{et al.}, Nat. Photonics \textbf{7}, 702 (2013)] In the present study, we investigate the effect of a stripline electrode on the coherent terahertz emission from Bi-2212 intrinsic junctions. We observed peculiar emission patterns with temperature-independent stripes in the current-voltage characteristics. We analyzed the experimental data using an electromagnetic simulator to investigate the impedance matching conditions for efficient terahertz emission from Bi-2212 mesas. [Preview Abstract] |
Friday, March 17, 2017 12:51PM - 1:03PM |
Y38.00009: Terahertz emission from thermally-managed square intrinsic Josephson junction microstrip antennas Richard Klemm, Andrew Davis, Qing Wang We show for thin square microstrip antennas that the transverse magnetic electromagnetic cavity modes are greatly restricted in number due to the point group symmetry of a square. For the ten lowest frequency emissions, we present plots of the orthonormal wave functions and of the angular distributions of the emission power obtained from the uniform Josephson current source and from the excitation of an electromagnetic cavity mode excited in the intrinsic Josephson junctions between the layers of a highly anisotropic layered superconductor. [Preview Abstract] |
Friday, March 17, 2017 1:03PM - 1:15PM |
Y38.00010: Cavity mode enhancement of terahertz emission from equilateral triangular microstrip antennas of the high-$T_c$ superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ Constance Doty, Daniel Cerkoney, Ashley Gramajo, Tyler Campbell, Candy Reid, Manuel Morales, Kaveh Delfanazari, Takashi Yamamoto, Manabu Tsujimoto, Takanari Kashiwagi, Chiharu Watanabe, Hidetoshi Minami, Kazuo Kadowaki, Richard Klemm We study the transverse magnetic (TM) electromagnetic cavity mode wave functions for an ideal equilateral triangular microstrip antenna exhibiting C$_{3v}$ point group symmetry, which restricts the number of TM(n,m) modes to $|m-n|=3p$, where the integer $p >0$ for the modes odd and even about the three mirror planes, but $p=0$ can also exist for the even modes. We calculate the wave functions and the power distribution forms from the uniform Josephson current source and from the excitation of one of these cavity modes, and fit data on an early equilateral triangular Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ mesa, for which the C$_{3v}$ symmetry was apparently broken. [Preview Abstract] |
Friday, March 17, 2017 1:15PM - 1:27PM |
Y38.00011: A semiconductor nanowire Josephson junction microwave laser Maja Cassidy, Willemijn Uilhoorn, James Kroll, Damaz de Jong, David van Woerkom, Jesper Nygard, Peter Krogstrup, Leo Kouwenhoven We present measurements of microwave lasing from a single Al/InAs/Al nanowire Josephson junction strongly coupled to a high quality factor superconducting cavity. Application of a DC bias voltage to the Josephson junction results in photon emission into the cavity when the bias voltage is equal to a multiple of the cavity frequency. At large voltage biases, the strong non-linearity of the circuit allows for efficient down conversion of high frequency microwave photons down to multiple photons at the fundamental frequency of the cavity. In this regime, the emission linewidth narrows significantly below the bare cavity linewidth to $<$ 10 kHz and real time analysis of the emission statistics shows above threshold lasing with a power conversion efficiency $>$ 50\%. The junction-cavity coupling and laser emission can be tuned rapidly via an external gate, making it suitable to be integrated into a scalable qubit architecture as a versatile source of coherent microwave radiation. [Preview Abstract] |
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