Bulletin of the American Physical Society
APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014; Denver, Colorado
Session Q38: Superconducting Qubits: Amplifiers & Readout |
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Sponsoring Units: GQI Chair: Stefano Poletto, University of Delft Room: 709/711 |
Wednesday, March 5, 2014 2:30PM - 2:42PM |
Q38.00001: Photon tomography of a Josephson Parametric Amplifier William Kindel, Michael Schroer, Gene Hilton, Leila Vale, Martin Sandberg, Michael Vissers, Jiansong Gao, David Pappas, Lehnert Konrad Josephson Parametric Amplifiers (JPAs) are an important resource for quantum limited measurement, feedback and nonclassical state generation. To study the JPA transformation, we use a superconducting qubit-cavity system to launch single photons or, n=1 Fock states, into a JPA, which measures the state. From repeated measurements, we can infer the state's loss of purity as a results of the JPA transformation. We will present our estimates of the JPA's efficiency as a photon detector along with progress toward measuring arbitrary superpositions of n=0 and n=1 Fock states. [Preview Abstract] |
Wednesday, March 5, 2014 2:42PM - 2:54PM |
Q38.00002: Design and operation of novel Josephson parametric amplifiers for QND supeconducting qubit readout A. Narla, K.M. Sliwa, M. Hatridge, S. Shankar, L. Frunzio, R.J. Schoelkopf, M.H. Devoret Parametric amplifiers based on Josephson junctions are essential tools in superconducting quantum information experiments. However, their integration with current 3D Circuit QED experiments is made challenging by the need to transition between waveguide, coax and printed circuit boards. Moreover, these amplifiers need auxiliary microwave components, like hybrids and directional couplers, that are sources of spurious losses and/or difficult-to-predict impedance mismatch that can limit measurement efficiency. We develop a new architecture for these parametric amplifiers that eliminates superfluous microwave components and interconnects. This simplifies their assembly and integration into experiments. We present an experimental realization of such a device that demonstrates 20 dB of gain with 17 MHz BW at 11.4 GHz, on par with conventional devices. [Preview Abstract] |
Wednesday, March 5, 2014 2:54PM - 3:06PM |
Q38.00003: Qubit readout with a directional parametric amplifier K.M. Sliwa, B. Abdo, A. Narla, S. Shankar, M. Hatridge, L. Frunzio, R.J. Schoelkopf, M.H. Devoret Josephson junction based quantum limited parametric amplifiers play an essential role in superconducting qubit measurements. These measurements necessitate circulators and isolators between the amplifier and qubit to add directionality and/or isolation. Unfortunately, this extra hardware limits both quantum measurement efficiency and experimental scalability. Here we present a quantum-limited Josephson-junction-based directional amplifier (JDA) based on a novel coupling between two nominally identical Josephson parametric converters (JPCs). The device achieves a forward gain of 11 dB with a 15 MHz dynamical bandwidth, but higher gains are possible at the expense of bandwidth. We also present measurements of a transmon qubit made with the JDA, and show minimal measurement back-action despite the absence of any isolator or circulator before the amplifier. These results provide a first step toward realizing on-chip integration of qubits and parametric amplifiers. [Preview Abstract] |
Wednesday, March 5, 2014 3:06PM - 3:18PM |
Q38.00004: Josephson traveling-wave parametric amplifier for superconducting qubit readout Chris Macklin, D.H. Slichter, O. Yaakobi, L. Friedland, V. Bolkhovsky, D.A. Braje, G. Fitch, W.D. Oliver, I. Siddiqi Superconducting parametric amplifiers (paramps) have successfully demonstrated near quantum limited sensitivity, enabling single-shot qubit readout, feedback, and state tracking. However, these amplifiers are commonly limited to narrow bandwidth and modest dynamic range, and most require microwave circulators to separate input and output modes. These limitations stem from the use of a resonant non-linearity to achieve mixing between a signal and pump mode. Our traveling-wave parametric amplifier (TWPA) is based on a superconducting nonlinear Josephson junction transmission line, thereby inherently sidestepping the limitations associated with a cavity structure. We present theoretical predictions and experimental results, including improved gain and noise performance. We discuss transmon qubit readout in the circuit QED architecture using a TWPA. We also comment on promising architectures for chip-level integration and multiplexing. [Preview Abstract] |
Wednesday, March 5, 2014 3:18PM - 3:30PM |
Q38.00005: Development of integrated, on-chip microwave amplifiers for superconducting qubit measurement D.M. Toyli, A. Eddins, E.M. Levenson-Falk, S. Khan, A.A. Clerk, R. Vijay, I. Siddiqi In recent years, superconducting parametric amplifiers (paramps) have become essential tools for quantum-limited measurement of superconducting qubits. Despite the utility of such paramps in quantum measurement, feedback, and metrology, current hardware configurations require that paramps be isolated from qubits by lossy and bulky microwave components that limit their quantum efficiency and scalability. Here we describe progress toward achieving fast, high-fidelity qubit measurement using on-chip microwave amplifiers. Our approach is based on engineering weak nonlinearity into linear circuits conventionally used for circuit QED readout and probing these systems in a manner that enables independent control of the phases of the measurement and amplification processes. We report on device design, performance calculations, and preliminary measurements of integrated qubit-amplifier devices. [Preview Abstract] |
Wednesday, March 5, 2014 3:30PM - 3:42PM |
Q38.00006: Enhanced Dynamic Range in $N$-SQUID Lumped Josephson Parametric Amplifiers A. Eddins, E.M. Levenson-Falk, D.M. Toyli, R. Vijay, Z. Minev, I. Siddiqi Simultaneously providing high gain and nearly quantum-limited noise performance, superconducting parametric amplifiers (paramps) have been used successfully for high fidelity qubit readout, quantum feedback, and microwave quantum optics experiments. The Lumped Josephson Parametric Amplifier (LJPA) consists of a capacitively shunted SQUID coupled to a transmission line to form a nonlinear resonator. Like other paramps employing a resonant circuit, the LJPA's dynamic range--a potentially key ingredient for multiplexing--is limited. Simple theory predicts that the dynamic range can be increased without any reduction in bandwidth or gain by distributing the resonator nonlinearity over a series array of SQUIDs. We fabricated such array devices with up to 5 SQUIDs and observed a clear increase in the critical power for bifurcation about which parametric gain occurs. We discuss in detail amplifier performance as a function of the number of SQUIDs in the array. [Preview Abstract] |
Wednesday, March 5, 2014 3:42PM - 3:54PM |
Q38.00007: A Broadband Quantum-Limited Josephson Parametric Amplifier, Part I: Exp. T.C. White, R. Barends, J. Bochmann, B. Campbell, Y. Chen, Z. Chen, B. Chiaro, A. Dunsworth, E. Jeffrey, J. Kelly, A. Megrant, J.Y. Mutus, C. Neill, P. O'Malley, C. Quintana, P. Roushan, D. Sank, A. Vainsencher, J. Wenner, A.N. Cleland, J.M. Martinis While Josephson parametric amplifiers (JPA) have achieved noise performance near the quantum limit, their bandwidth and saturation power is constrained by the resonant design. For a 50 ohm environment the relationship between junction critical current, frequency, and coupled Q means that bandwidth and saturation vary inversely. We present a device in which the coupled Q was lowered by engineering the environment impedance, increasing both bandwidth and saturation power without changing the resonator circuit parameters. The 50 ohm environment was transformed to 15 ohms at the resonator using a hybrid co-planar waveguide/micro-strip transmission line to create a broadband impedance matching network. This device exhibits regions with near quantum-limited bandwidth exceeding 700 MHz and saturation powers as high as -105 dBm. [Preview Abstract] |
Wednesday, March 5, 2014 3:54PM - 4:06PM |
Q38.00008: A Broadband Quantum-Limited Josephson Parametric Amplifier. Part II: Theory Josh Mutus, R. Barends, J. Bochmann, B. Campbell, Y. Chen, Z. Chen, B. Chiaro, A. Dunsworth, E. Jeffrey, J. Kelly, A. Megrant, C. Neill, P. O'Malley, C. Quintana, P. Roushan, D. Sank, A. Vainsencher, J. Wenner, T.C. White, A.N. Cleland, J.M. Martinis The quantum-limited nature of the Josephson parametric amplifier (JPA) has enabled exquisite studies of single qubit dynamics. Scaling up to larger quantum systems and higher-power dynamics requires wider bandwidth and higher saturation power. We demonstrate that both bandwidth and saturation power can be increased by an order of magnitude through careful engineering of the frequency dependent impedance environment. We can understand and engineer the interaction between the JPA and this environment using the ``pumpistor'' model, in which the flux-pumped SQUID is treated as a linear circuit element. At extreme low Q this interaction, previously viewed as a parasitic effect, can be used to greatly enhance bandwidth while maintaining the robust noise performance of the JPA. [Preview Abstract] |
Wednesday, March 5, 2014 4:06PM - 4:18PM |
Q38.00009: Squeezing with a flux-driven Josephson parametric amplifier E.P. Menzel, L. Zhong, P. Eder, A. Baust, M. Haeberlein, E. Hoffmann, F. Deppe, A. Marx, R. Gross, R. Di Candia, E. Solano, M. Ihmig, K. Inomata, T. Yamamoto, Y. Nakamura Josephson parametric amplifiers (JPA) are promising devices for the implementation of continuous-variable quantum communication protocols. Operated in the phase-sensitive mode, they allow for amplifying a single quadrature of the electromagnetic field without adding any noise. While in practice internal losses introduce a finite amount of noise, our device still adds less noise than an ideal phase-insensitive amplifier. This property is a prerequisite for the generation of squeezed states. In this work, we reconstruct the Wigner function of squeezed vacuum, squeezed thermal and squeezed coherent states with our dual-path method [L. Zhong et al. arXiv:1307.7285 (2013); E. P. Menzel et al. Phys. Rev. Lett. 105 100401 (2010)]. In addition, we illuminate the physics of squeezed coherent microwave fields. This work is supported by SFB 631, German Excellence Initiative via NIM, EU projects SOLID, CCQED, PROMISCE and SCALEQIT, MEXT Kakenhi ``Quantum Cybernetics,'' JSPS FIRST Program, the NICT Commissioned Research, Basque Government IT472-10, Spanish MINECO FIS2012-36673-C03-02, and UPV/EHU UFI 11/55. [Preview Abstract] |
Wednesday, March 5, 2014 4:18PM - 4:30PM |
Q38.00010: Efficient Qubit Readout Using Josephson Photomultipliers E.J. Pritchett, L.C.G. Govia, C. Xu, M.G. Vavilov, B.L.T. Plourde, R. McDermott, F.K. Wilhelm A Josephson photomultplier (JPM) -- a current-biased Josephson junction operated near its critical bias -- can absorb and detect weak microwave signals with high sensitivity (PRL 107, 217401 (2011)). When strongly coupled to a high-Q transmission line ``cavity,'' the JPM can detect single microwave photons with large bandwidth and with near unit efficiency (PRB 86, 174506 (2012)). The switching of a JPM into its voltage state acts on the adjacent cavity via the backaction of photon subtraction (PRA 86, 032311 (2012)). While a destructive measurement of the microwave cavity, this switching can perform a binary non-demolition measurement of a quantum system coupled to the cavity. We present a protocol by which the presence and subsequent detection of a cavity photon by a JPM conveys information about the state of a superconducting qubit without destroying it, thus performing a quantum non-demolition measurement of the qubit's state. Multi-qubit generalizations of this protocol are discussed. [Preview Abstract] |
Wednesday, March 5, 2014 4:30PM - 4:42PM |
Q38.00011: Josephson parametric phase-locked oscillator: application to dispersive readout of superconducting qubits Zhirong Lin, Kunihiro Inomata, William Oliver, Kazuki Koshino, Yasunobu Nakamura, Jaw-Shen Tsai, Tsuyoshi Yamamoto We present a new qubit readout scheme using a Josephson parametric phase-locked oscillator. The parametric oscillator is the same circuit as the flux-driven parametric amplifier used in Refs. 1 and 2, but is operated at the pump power above the oscillation threshold. The oscillator works as a sensitive binary phase detector and discriminates the dispersive phase shifts in the probe microwave field reflected from a resonator coupled to a qubit. The scheme offers fast and latching-type readout, but requires only a small number of photons in the resonator. Using this scheme, we achieved high-fidelity single-shot readout of a flux qubit with more than 90$\%$ contrast of Rabi oscillations. [1] T. Yamamoto {\it et al.}, APL {\bf 93}, 042510 (2008). [2] Z. R. Lin {\it et al.}, APL {\bf 103}, 132602 (2013). [Preview Abstract] |
Wednesday, March 5, 2014 4:42PM - 4:54PM |
Q38.00012: Kinetic Inductance Traveling-wave Parametric Amplifier for Qubit and Detector Readout Jiansong Gao, Mike Vissers, Martin Sandberg, Saptarshi Chaudhuri, Clint Bockstiegel, Christopher Abeles, Kent Irwin, David Pappas A broadband quantum-limited amplifier is desired for multiplexed readout of superconducting qubits and detectors. Kinetic inductance traveling-wave parametric amplifier (KIT) is a new type of amplifier that utilizes the intrinsic nonlinearity of kinetic inductance of superconductor for parametric amplification. By applying dispersion engineering, KIT amplifier can achieve quantum-limited noise over a broad bandwidth. We have designed a KIT amplifier which consists of a 2-m long coplanar waveguide fabricated from 20 nm NbTiN film on Si wafer. We have achieved over 10dB gain in a bandwidth from 5 to 11 GHz. We have found the maximum gain is limited by abrupt breakdown at defects in the transmission line. By cascading two devices, more than 20 dB of gain was achieved from 5 to 12 GHz. We are also designing a travel-wave version of Josephson parametric amplifier with GHz bandwidth by applying dispersion engineering. [Preview Abstract] |
Wednesday, March 5, 2014 4:54PM - 5:06PM |
Q38.00013: In-situ characterization of a SQUID MSA located within the Axion Dark Matter eXperiment Andrew Wagner The Axion Dark Matter eXperiment (ADMX) is designed to detect ultra-weakly interacting relic axion particles by searching for their conversion to microwave photons in a resonant cavity immersed in a high magnetic field. A SQUID micro-strip amplifier (MSA) is used as the first stage amplifier in ADMX to achieve a near quantum limited system noise temperature. The in-situ characterization of a SQUID MSA within this large experiment and high magnetic field environment is presented. The possibility of improving the sensitivity of ADMX with Josephson parametric amplifiers and superconducting qubits is also discussed. [Preview Abstract] |
Wednesday, March 5, 2014 5:06PM - 5:18PM |
Q38.00014: High-Fidelity Qubit Measurement using a Superconducting Low-Inductance Undulatory Galvanometer Microwave Amplifier Ted Thorbeck, David Hover, Shaojiang Zhu, Guilhem Ribeill, Daniel Sank, Rami Barends, John Martinis, Robert McDermott We describe a high-fidelity dispersive measurement of a superconducting Xmon qubit using a microwave amplifier based on the Superconducting Low-inductance Undulatory Galvanometer (SLUG). We will show a qubit measurement fidelity of 99{\%} in 700 ns with the SLUG, compared to 60{\%} without the SLUG. The SLUG amplifier has a gain of 19 dB at 6.6 GHZ. It also improves the signal-to-noise ratio by 9 dB, compared the same circuit without the SLUG. Also, the SLUG amplifier has a large dynamic range, with an input saturation power corresponding to around 600 photons in the readout cavity. All of these properties make the SLUG a promising microwave amplifier for more complex quantum circuits. [Preview Abstract] |
Wednesday, March 5, 2014 5:18PM - 5:30PM |
Q38.00015: Tunable resonant and non-resonant interactions between a phase qubit and LC resonator Michael Shane Allman, Jed D. Whittaker, Manuel Castellanos-Beltran, Katarina Cicak, Fabio da Silva, Michael Defeo, Florent Lecocq, Adam Sirois, John Teufel, Jose Aumentado, Raymond W. Simmonds We use a flux-biased radio frequency superconducting quantum interference device (rf SQUID) with an embedded flux-biased direct current (dc) SQUID to generate strong resonant and non-resonant tunable interactions between a phase qubit and a lumped-element resonator. The rf-SQUID creates a tunable magnetic susceptibility between the qubit and resonator providing resonant coupling rates from zero to near the ultra-strong coupling regime. By modulating the magnetic susceptibility, non-resonant parametric coupling achieves rates $>100\,\rm{MHz}$. Nonlinearity of the magnetic susceptibility also leads to parametric coupling at subharmonics of the qubit-resonator detuning. Controllable coupling is generically important for constructing coupled-mode systems ubiquitous in physics, useful for both, quantum information architectures and quantum simulators. [Preview Abstract] |
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