Bulletin of the American Physical Society
APS March Meeting 2015
Volume 60, Number 1
Monday–Friday, March 2–6, 2015; San Antonio, Texas
Session G39: Superconducting Circuits: Amplifiers II |
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Sponsoring Units: GQI Chair: Josh Mutus, Google Inc, Santa Barbara Room: 213AB |
Tuesday, March 3, 2015 11:15AM - 11:27AM |
G39.00001: Improving the dynamic range of the Josephson Bifurcation Amplifier Laszlo Szocs, Michael Hatridge, Shyam Shankar, Anirudh Narla, Katrina Sliwa, Michel Devoret The dynamic range of the Josephson Bifurcation Amplifier (JBA), acting as a phase-sensitive amplifier, can be improved by combination of several junctions in series and parallel in place of the single junction present in the original device. By analyzing the circuit Hamiltonian for a system with many amplifiers tiled in parallel, each containing junctions wired in series, a potential increase in the amplifier's dynamic range can be obtained while maintaining GHz-range tunability. Theoretical results and preliminary experimental data will be presented. [Preview Abstract] |
Tuesday, March 3, 2015 11:27AM - 11:39AM |
G39.00002: Multi-mode directional parametric devices Leonardo Ranzani, Adam Sirois, Manuel Castellanos-Beltran, Raymond Simmonds, John Teufel, Jose Aumentado Josephson parametric amplifiers (JPAs) are very common in quantum information measurement systems, because they can operate close to the standard quantum limit, but require an external circulator to achieve unidirectionality. A possible way to achieve directional amplification without a circulator is to increase the number of coupled modes. By parametrically coupling three or more modes, and selecting the right amplitude and phase for the mode coupling rates, we can realize a non-trivial interference between different internal parametric processes and obtain unidirectional frequency conversion or amplification. In this talk we are going to discuss some recent progress on the experimental implementation of directional lumped-element Josephson parametric devices based on multiple coupled modes. [Preview Abstract] |
Tuesday, March 3, 2015 11:39AM - 11:51AM |
G39.00003: Directional Amplification using Josephson Ring Modulators M. Hatridge, K.M. Sliwa, A. Narla, S. Shankar, M.H. Devoret Quantum limited parametric amplifiers usually amplify in reflection, so that the input and output signals travel on the same physical port. Circulators and isolators are thus required both to separate input and output signals with minimal loss of signal-to-noise ratio and to avoid backward irradiation of the signal source. These devices are bulky, dissipative, and operate in large magnetic fields which make them incompatible with integration on chip. By interfering the non-reciprocal mixing processes present in Josephson Ring Modulators, directional amplification can be realized. The theory and performance of a novel directional amplifier will be presented. [Preview Abstract] |
Tuesday, March 3, 2015 11:51AM - 12:03PM |
G39.00004: A new implementation of a Josephson microwave circulator K.M. Sliwa, M. Hatridge, A. Narla, S. Shankar, M.H. Devoret Circulators are essential microwave components in superconducting qubit experiments, particularly those which also use parametric amplifiers. These amplifiers typically operate in reflection, and circulators both separate input from output, and protect the qubit from dephasing due to tones reflected off the amplifier. Unfortunately, their large size and the large magnetic fields they need to operate make them impossible to integrate on chip. Here we present the theory and experimental performance of a microwave circulator based not on ferrite materials, but on the interference of non-reciprocal mixing processes present in Josephson Ring Modulators. [Preview Abstract] |
Tuesday, March 3, 2015 12:03PM - 12:15PM |
G39.00005: Qubit readout with Josephson Photomultipliers Guilhem Ribeill, Ivan Pechenezhski, Ted Thorbeck, Caleb Howington, Matthew Hutchings, Luke Govia, Frank Wilhelm, B.L.T. Plourde, Robert McDermott Continued progress in superconducting qubits will require the development of scalable quantum-limited measurement tools. We have recently introduced a scalable superconducting qubit measurement protocol involving the state-selective ringup of a readout cavity followed by photodetection with the Josephson photomultiplier (JPM), a current-biased Josephson junction. Here we describe the experimental realization of this protocol. We discuss JPM optimization for high quantum efficiency, and describe integration of the JPM with a transmon qubit for high-fidelity dispersive readout. In addition, we discuss prospects for JPM readout of larger multi-qubit circuits. [Preview Abstract] |
Tuesday, March 3, 2015 12:15PM - 12:27PM |
G39.00006: Readout of superconducting qubits with a Josephson photomultiplier Caleb Howington, Matthew Hutchings, Guilhem Ribeill, Robert McDermott, B.L.T. Plourde A Josephson photomultiplier (JPM) formed from a current-biased Josephson junction is the centerpiece of an alternative method for measuring the state of a superconducting qubit in a microwave cavity compared to conventional linear amplification followed by heterodyne readout. This approach, which involves mapping the qubit state onto the cavity photon occupation followed by photon detection with the JPM, reduces the requirements on bulky microwave hardware and amplifiers in the cryostat. We will discuss the implementation of superconducting microwave cavities and transmon qubits tailored for this readout technique. Furthermore, we will present steps towards the readout of multiple qubits in a common cavity with the JPM-based protocol. [Preview Abstract] |
Tuesday, March 3, 2015 12:27PM - 12:39PM |
G39.00007: Efficient photon detection with a Josephson Parametric Amplifier W.F. Kindel, M.D. Schroer, M.R. Vissers, J. Gao, D.P. Pappas, K.W. Lehnert Josephson Parametric Amplifiers (JPAs) are an important resource in 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 in comparison to Gaussian characterization methods. [Preview Abstract] |
Tuesday, March 3, 2015 12:39PM - 12:51PM |
G39.00008: Towards a lossless and integrable circulator for quantum superconducting microwave systems: Theory of operation Joseph Kerckhoff, Benjamin J. Chapman, Kevin Lalumi\`ere, Alexandre Blais, K.W. Lehnert Lossless and integrable microwave circulators operating in the 4-8 GHz band are a critical, missing component in superconducting microwave quantum technology. Circulators are non-reciprocal devices used to impose a unidirectional flow of microwave signals. We report on progress towards an all-superconducting microwave circuit potentially capable of integrating with other quantum technologies and replacing many instances of the lossy and non-integrable ferrite circulators used in all contemporary quantum microwave experiments. Non-reciprocity is achieved through relatively weak (sub-Gauss) and slow ($\sim$ 100 MHz) dynamically-modulated magnetic fields that tune the linear susceptibility of SQUID arrays in a four-port, resonant circuit. Our design's basic theory of operation will be covered in this presentation. [Preview Abstract] |
Tuesday, March 3, 2015 12:51PM - 1:03PM |
G39.00009: Towards a lossless and integrable circulator for quantum superconducting microwave systems: design and initial testing Benjamin J. Chapman, Joseph Kerckhoff, Kevin Lalumi\`{e}re, Alexandre Blais, K.W. Lehnert Microwave circulators enforce a single propagation direction for the signals in an electrical network. Commercial circulators, however, are lossy and cannot be integrated near superconducting circuits because of the large magnetic fields they emit. We report on progress toward the development of a lossless, on-chip, active circulator for superconducting microwave circuits in the 4-8 GHz band. Non-reciprocity is achieved by the active modulation of circuit elements on a slow time scale (100 MHz). The circulator's active components are dynamically tunable inductors constructed from series arrays of SQUIDs. SQUID inductance is tuned by varying the magnetic flux through the SQUID's loop with fields weaker than 1 G. Device features include a tunable bandwidth between 10-100 MHz, a tunable center frequency between 4-8 GHz, a high (-93 dBm) saturation power, a factor of 50 separation between the center and modulation frequencies, low loss, and 1 mm$^2$ footprint. This presentation will cover the design and initial testing of the device. [Preview Abstract] |
Tuesday, March 3, 2015 1:03PM - 1:15PM |
G39.00010: Towards a lossless and integrable circulator for quantum superconducting microwave systems: modelling and optimization Kevin Lalumiere, Joseph Kerckhoff, Benjamin J. Chapman, K.W. Lehnert, Alexandre Blais Microwave circulators are non-reciprocal devices allowing, for example, isolation of superconducting qubits from amplifier noise. Unfortunately, current commercial circulators are bulky and are moreover based on permanent magnets, prohibiting on-chip integration with superconducting quantum circuits. In this talk we show that an on-chip superconducting circulator can be realized by modulating the coupling between resonant modes and input/output transmission lines. The performance of this circulator depends on how the coupling is modulated. Using input-output theory, we obtain a transfer operator description of the circulator under arbitrary modulation, and show how to optimize the design and modulation scheme. We further show how this design minimizes frequency mixing between incident and scattered signals. [Preview Abstract] |
Tuesday, March 3, 2015 1:15PM - 1:27PM |
G39.00011: Multiplexed Readout of Transmon Qubits with Josephson Bifurcation Amplifiers Vivien Schmitt, Daniel Esteve, Xin Zhou, Kristinn Juliusson, Alexandre Blais, Patrice Bertet, Denis Vion Achieving individual qubit readout is a major challenge in the development of scalable superconducting quantum processors. We have implemented the multiplexed readout of a four transmon qubit circuit using non-linear resonators operated as Josephson bifurcation amplifiers. We demonstrate the simultaneous measurement of Rabi oscillations of the four transmons. We find that multiplexed Josephson bifurcation is a high-fidelity readout method, the scalability of which is not limited by the need of a large bandwidth nearly quantum-limited amplifier as is the case with linear readout resonators. [Preview Abstract] |
Tuesday, March 3, 2015 1:27PM - 1:39PM |
G39.00012: Noise and Directionality in a SLUG Microwave Amplifier for Superconducting Qubit Readout Ted Thorbeck, Shaojiang Zhu, Edward Leonard, Robert McDermott Josephson parametric amplifiers have been widely used for low-noise dispersive readout of superconducting qubits. However, multiple stages of cryogenic isolation are required to protect the qubit from the strong microwave pump tone and from the high temperature noise of downstream gain stages. We want to remove circulators and isolators from the measurement chain because they are bulky, expensive, and magnetic. The SLUG (superconducting low-inductance undulatory galvanometer) is a microwave amplifier that achieves broad bandwidth, low added noise, and high gain. In this talk we discuss measurements of the SLUG added noise (less than photon system added noise). We describe theoretical and experimental investigations of the SLUG reverse isolation. Finally, we discuss backaction of the SLUG on the measured qubit, and we present strategies for the suppression of SLUG backaction. [Preview Abstract] |
Tuesday, March 3, 2015 1:39PM - 1:51PM |
G39.00013: Characterization of SLUG microwave amplifiers I.-C. Hoi, S. Zhu, T. Thorbeck, R. McDermott, J. Mutus, E. Jeffrey, R. Barends, Y. Chen, P. Roushan, A. Fowler, D. Sank, T. White, B. Campbell, Z. Chen, B. Chiaro, A. Dunsworth, J. Kelly, A. Megrant, C. Neill, P.J.J. O'Malley, C. Quintana, A. Vainsencher, J. Wenner, J.M. Martinis With the rapid growth of superconducting circuits quantum technology, a near quantum-limited amplifier at GHz frequency is needed to enable high fidelity measurements. We describe such an amplifier, the SQUID based, superconducting low inductance undulatory galvanometer (SLUG) amplifier. We measure the full scattering matrix of the SLUG. In particular, we measure both forward and reverse gain, as well as reflection. We see 15dB forward gain with added noise from one quanta to several quanta. The -1 dB compression point is around -95 dBm, about two orders of magnitude higher than that of typical Josephson parametric amplifiers. With these properties, SLUG is well suited for the high fidelity, simultaneous multiplexed readout of superconducting qubits. [Preview Abstract] |
Tuesday, March 3, 2015 1:51PM - 2:03PM |
G39.00014: Noise Characteristics of Superconducting Low-Inductance Undulatory Galvanometer Wenshuo Liu, Maxim Vavilov, Robert McDermott We describe theoretical studies of the Superconducting Low-Inductance Undulatory Galvanometer (SLUG), a non-reciprocal gain element based on Josephson junctions. We use both analytical and numerical methods to calculate various properties of the SLUG, including power gain, added noise and back-action in both the thermal and quantum regimes. We derive the distribution functions of the output signals in the presence of classical noise using the Fokker-Planck equation. We also discuss optimal matching of the SLUG amplifier so that gain, bandwidth and noise performance can meet the criteria of high-fidelity multiplexed qubit readout. [Preview Abstract] |
Tuesday, March 3, 2015 2:03PM - 2:15PM |
G39.00015: Experimental Studies of a Driven PT Dimer Mahboobeh Chitsazi, Nicholas Bender, Luis Fowler-Gerace, Huanan Li, Fred Ellis, Tsampikos Kottos We experimentally investigate a driven PT system consisting of two Ultra-High-Frequency oscillators coupled by a time-dependent capacitance. The experimental circuit uses active feedback controlled by photocells for the implementation of gain and loss, along with varicaps for the time dependent coupling. We show that this system is mapped to a one-dimensional Floquet lattice with local PT-symmetry. This isomorphism allows us to experimentally investigate PT-dynamics in extended lattices. [Preview Abstract] |
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