Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session E51: Readout in Superconducting Qubits: Parametric and Novel MeasurementsFocus
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Sponsoring Units: GQI Chair: Leonardo Ranzani, Raytheon BBN Technologies Room: 398 |
Tuesday, March 14, 2017 8:00AM - 8:36AM |
E51.00001: Simultaneous single-shot readout of multi-qubit circuits using a traveling-wave parametric amplifier Invited Speaker: Kevin O'Brien Observing and controlling the state of ever larger quantum systems is critical for advancing quantum computation. Utilizing a Josephson traveling wave parametric amplifier (JTWPA), we demonstrate simultaneous multiplexed single shot readout of 10 transmon qubits in a planar architecture. We employ digital image sideband rejection to eliminate noise at the image frequencies. We quantify crosstalk and infidelity due to simultaneous readout and control of multiple qubits. Based on current amplifier technology, this approach can scale to simultaneous readout of at least 20 qubits. [Preview Abstract] |
Tuesday, March 14, 2017 8:36AM - 8:48AM |
E51.00002: Squeezed Light Generation Using a Josephson Traveling Wave Parametric Amplifier in Three-Wave Mixing Yanjie Qiu, Andrew Eddins, Kevin O'Brien, Irfan Siddiqi The generation of highly-squeezed states using superconducting amplifiers is a valuable tool for quantum optics and quantum metrology in the microwave domain. However, conventional Josephson parametric amplifiers can be limited with respect to squeezing strength, often due to the relatively strong nonlinearity of cavity-based devices. Recently, Josephson traveling-wave parametric amplifiers (JTWPA) have been developed exhibiting large dynamic range with a 1dB compression point around -100dBm at the input of the JTWPA and over 3 GHz bandwidth [1]. The high saturation power of these devices makes them promising candidates for generating highly squeezed states. In this talk, we present a novel scheme for operating a JTWPA in three-wave mixing mode, and discuss our investigations of the JTWPA squeezing performance. \textit{[1] C. Macklin, K. O'Brien, D. Hover, M. E. Schwartz, V. Bolkhovsky, X. Zhang, W. D. Oliver, and I. Siddiqi, Science 350, 307 (2015)} [Preview Abstract] |
Tuesday, March 14, 2017 8:48AM - 9:00AM |
E51.00003: Optimal Design of a Traveling-Wave Kinetic Inductance Amplifier Operated in Three-Wave Mixing Mode Robert Erickson, Mustafa Bal, Ksiang-Sheng Ku, Xian Wu, David Pappas In the presence of a DC bias, an injected pump, of frequency $f_P$, and a signal, of frequency $f_S$, undergo parametric three-way mixing (3WM) within a traveling-wave kinetic inductance (KIT) amplifier, producing an idler product of frequency $f_I=f_P-f_S$. [M. R. Vissers, R. P. Erickson, H.-S. Ku, Leila Vale, Xian Wu, G. C. Hilton, and D. P. Pappas, Appl. Phys. Lett. 108, 012601 (2016).] Periodic frequency stops are engineered into the coplanar waveguide of the device to enhance signal amplification. With $f_P$ placed just above the first frequency stop gap, 3WM broadband signal gain is achieved with maximum gain at $f_S=f_P/2$. Within a theory of the dispersion of traveling waves in the presence of these engineered loadings [R. P. Erickson and D. P. Pappas, to be submitted to Phys. Rev. B.], which accounts for this broadband signal gain, we show how an optimal frequency-stop design may be constructed to achieve maximum signal amplification. The optimization approach we describe can be applied to the design of other nonlinear traveling-wave parametric amplifiers. [Preview Abstract] |
Tuesday, March 14, 2017 9:00AM - 9:12AM |
E51.00004: Suppression of Gain Ripples in Superconducting Traveling-Wave Kinetic Inductance Amplifiers Mustafa Bal, Robert P. Erickson, Hsiang Sheng Ku, Xian Wu, David P. Pappas Superconducting traveling-wave kinetic inductance (KIT) amplifiers demonstrated gain over a wide bandwidth with high dynamic range and low noise. However, the gain curve exhibits ripples. Impedance mismatch at the input and output ports of the KIT amplifier as wells as split ground planes of the coplanar waveguide (CPW) geometry are potential contributors to the ripple in the gain curve. Here we study the origin of these ripples in KIT amplifiers configured in CPW geometry using approximately 20 nm thick NbTiN films grown by reactive co-sputtering of NbN and TiN. Our NbTiN films have non-linear kinetic inductance as a function of current, described by $L=L_{0}(1+(I/I_{*})^{2})$, where $I_{*}=15.96 \pm 0.11$ mA measured by time domain reflectometry. We report the results of implementing an impedance taper that takes into account a significantly reduced phase velocity as it narrows, adding Au onto the CPW split grounds, as well as employing different designs of dispersion engineering. Qubit Measurements using KIT amplifiers will also be reported. [Preview Abstract] |
Tuesday, March 14, 2017 9:12AM - 9:24AM |
E51.00005: A Multi-Channel Josephson Parametric Amplifier Michael Selvanayagam, Alexander Papageorge, Damon Russell, Nick Rubin, Mehrnoosh Vahdipour, Spike Curtis, Anthony Polloreno, Matthew Reagor, Chad Rigetti One of the challenges of constructing a multi-qubit system is putting in place a readout and amplification system capable of single-shot high-fidelity qubit state measurements. This readout system has been envisioned in a variety of ways including such ideas as multiplexing and broadband JPA's. We investigate a specific quantum circuit, where each qubit in an multi-qubit system has a dedicated lumped Josephson Parametric Amplifier. We discuss a scalable implementation of this system, including JPA design, circuit layout, ~packaging, calibration, ~and single-shot operation ~across multiple qubits. [Preview Abstract] |
Tuesday, March 14, 2017 9:24AM - 9:36AM |
E51.00006: Development of an Embedded Transmon Amplifier John Mark Kreikebaum, Andrew Eddins, David Toyli, Eli Levenson-Falk, Benjamin Levitan, Aashish Clerk, Irfan Siddiqi Superconducting parametric amplifiers offer high quantum efficiencies and near quantum limited noise performance, but typically require the addition of circulators which are lossy, bulky, and magnetic, limiting efficiency and precluding scalable on-chip integration. In this talk, we present experimental results on a superconducting Josephson parametric amplifier (JPA) dispersively coupled to an on-chip transmon qubit. By embedding the qubit inside the amplifier directly, loss before the first stage of amplification is essentially eliminated. Study of the measurement induced dephasing and measurement rates as a function of device gain and amplification quadrature can be achieved by sweeping the power of the JPA pump tone and the relative phase between pump and readout tones. Of primary interest is whether the on-chip gain can be used to enhance measurement rates without producing excess backaction on the qubit. We investigate device performance in both the strong projective and weak continuous readout regimes and quantitatively compare results to theoretical predictions. [Preview Abstract] |
Tuesday, March 14, 2017 9:36AM - 9:48AM |
E51.00007: Kerr-free, 3-wave mixing Josephson dipole element N.E. Frattini, U. Vool, S. Shankar, A. Narla, K.M. Sliwa, M.H. Devoret A necessary requirement for any quantum computation architecture is the ability to perform efficient quantum operations. For superconducting qubits, quantum-limited amplification and conversion operations can be realized with a quadrupole Josephson junction element behaving as a loss-less three-wave mixer, the Josephson Ring Modulator (JRM). A recent approach for through-only amplification requires the application of multiple strong microwave pump tones to the JRM. In practice, unwanted fourth order Kerr nonlinearities jeopardize delicate frequency matching conditions. We present a novel dipole circuit element with third order nonlinearity, which implements three-wave mixing without the addition of harmful Kerr terms. In addition to reducing power dependent frequency shifts, such a pure three-wave mixer can be tessellated for increased dynamic range or bandwidth. Experimental results for a non-degenerate amplifier based on the proposed pure third order non-linearity will be reported. [Preview Abstract] |
Tuesday, March 14, 2017 9:48AM - 10:00AM |
E51.00008: Improving the Efficiency of Josephson Photomultipliers Konstantin Nesterov, Marius Sch\"{o}ndorf, Alexander Opremcak, Ivan Pechenezhskiy, Robert McDermott, Frank Wilhelm, Maxim Vavilov We discuss possible strategies to increase the sensitivity of Josephson photomultipliers (JPMs) based on current-biased Josephson junctions connected to microwave transmission lines. These devices were previously proposed for high-fidelity readout [1]. We consider a JPM at the end of a semi-infinite transmission line (TL) and apply the input-output formalism to calculate contrast, which is defined as the difference between the detection probabilities with and without microwave radiation. We compare this contrast calculated for a JPM that is coupled to a TL directly with that achieved for setups with additional matching elements between the JPM and TL. We discuss the dependence of detection efficiency on the parameters of the microwave matching network. [1] Luke C. G. Govia, Emily J. Pritchett, Canran Xu, B. L. T. Plourde, Maxim G. Vavilov, Frank K. Wilhelm, and R. McDermott, Phys. Rev. A {\bf 90}, 062307 (2014). [Preview Abstract] |
Tuesday, March 14, 2017 10:00AM - 10:12AM |
E51.00009: Near quantum limited amplification from inelastic Cooper-pair tunneling Max Hofheinz, Salha Jebari, Florian Blanchet, Alexander Grimm, Dibyendu Hazra, Romain Albert, Fabien Portier Josephson parametric amplifiers approach quantum-limited noise performance but require strong external microwave pump tones which make them more difficult to use than DC powered amplifiers: The pump tone can affect the device under test and requires expensive room-temperature equipment. Inelastic Cooper pair tunneling processes through a small DC voltage-biased Josephson junction, where a tunneling Cooper pair dissipates its energy $2eV$ in the form of two photons are reminiscent of parametric down conversion. We show that these processes can be used to provide amplification near the quantum limit without external microwave pump tone. We explain the measured gain and noise based on the $P(E)$ theory of inelastic Cooper pair tunneling and general fluctuation--dissipation relations. [Preview Abstract] |
Tuesday, March 14, 2017 10:12AM - 10:24AM |
E51.00010: Multimode phase-locking in a Josephson parametric oscillator Andreas Bengtsson, Waltraut Wustmann, Vitaly Shumeiko, Per Delsing, Jonas Bylander Frequency-tunable resonators are versatile tools for microwave amplification at the quantum limit of sensitivity, interaction between qubits and radiation in the circuit-QED architecture, and strong-coupling microwave quantum optics. We investigated non-degenerate parametric resonance in multimode microwave superconducting resonators. Pumping is realized by modulating magnetic flux through the SQUID attached to the cavity. Pumping at the sum-frequency of two modes provides parametric amplification. For low pumping strength, we observe the generation of two-mode squeezed states, i.e., entangled modes when the input is the vacuum. For high pumping strength, exceeding a parametric instability threshold, self-sustained parametric oscillations are observed in each mode. The sum of the phases of the mode fields is fixed, while the difference is uncertain in the classical limit, and undergoes diffusion under the effect of quantum noise. This phenomenon significantly changes the statistics of entangled modes in the oscillator state. [Preview Abstract] |
Tuesday, March 14, 2017 10:24AM - 10:36AM |
E51.00011: Operating a Josephson parametric amplifier for optimal squeezing in a dark matter axion search Maxime Malnou, Daniel Palken, William Kindel, Leila Vale, Gene Hilton, Konrad Lehnert Microwave squeezing, as produced by a Josephson parametric amplifier (JPA), can accelerate a search for axionic dark matter [1]. In order to generate a squeezed state, the nonlinear SQUID inductance in a JPA resonant circuit may be pumped in three distinct ways: with a single tone near resonance [2], with a pair of tones symmetrically detuned from resonance [3], or with a flux tone near twice resonance [4]. In this talk, we present experimental comparisons among these different methods of generating a strong squeezed state, with particular attention given to the repercussions of each choice as regards the subsequent transport and measurement of the state. We additionally discuss the fundamental limitations upon squeezed state generation. [1] Zheng, H. et al. Preprint at https://arxiv.org/abs/1607.02529 (2016). [2] Mallet, F. et al. Quantum state tomography of an itinerant squeezed microwave field. Phys. Rev. Lett. 106, 220502 (2011). [3] Kamal, A. et al. Signal-to-pump back action and self-oscillation in double-pump Josephson parametric amplifier. Phys. Rev. B 79, 184301 (2009). [4] Yamamoto, T. et al. Flux-driven Josephson parametric amplifier. App. Phys. Lett. 93, 042510 (2008). [Preview Abstract] |
Tuesday, March 14, 2017 10:36AM - 10:48AM |
E51.00012: Towards 90{\%} efficient generation, transport, and readout of a microwave squeezed state Daniel Palken, Maxime Malnou, William Kindel, Leila Vale, Gene Hilton, Konrad Lehnert A Josephson parametric amplifier (JPA) can be used as a phase sensitive amplifier to create a squeezed state of the microwave vacuum, which can in turn be detected with a second JPA [1]. Such an arrangement, known as a squeezed state receiver, can be used to circumvent the vacuum fluctuations that ultimately limit the search for dark matter axions [2]. But the benefit of the squeezed state is diminished to the degree that the state is lost in transit from one JPA to the other. In this talk we detail the sources of loss in the microwave path, along with strategies for their minimization. In conjunction, we describe how the choice of JPA pump modality impacts this loss budget. [Preview Abstract] |
Tuesday, March 14, 2017 10:48AM - 11:00AM |
E51.00013: A photon capture approach to Josephson photomultiplier-based qubit measurement Alexander Opremcak, Ivan Pechenezhskiy, Caleb Howington, Chris Wilen, Matthew Beck, Edward Leonard Jr., Konstantin Nesterov, Maxim Vavilov, Britton Plourde, Robert McDermott Scalable high-fidelity qubit measurement is essential to the realization of a fault tolerant quantum processor. Here we outline a new approach whereby microwave pointers states are transferred between a dispersively coupled qubit readout resonator and an auxiliary resonator that is probed by a Josephson photomultplier (JPM). We describe the design, fabrication, and characterization of the JPM chips and discuss experiments to benchmark qubit measurement fidelity. These efforts are an intermediate step towards interfacing superconducting qubit circuits with Single Flux Quantum (SFQ) digital logic in order to reduce room temperature hardware overhead and latency of classical post-processing. [Preview Abstract] |
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