Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session S33: Hybrid Quantum SystemsFocus
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Sponsoring Units: DQI Chair: Vladimir Manucharyan, University of Maryland, College Park Room: LACC 408B |
Thursday, March 8, 2018 11:15AM - 11:51AM |
S33.00001: TBD Invited Speaker: John Teufel This abstract not available. |
Thursday, March 8, 2018 11:51AM - 12:03PM |
S33.00002: Scalable Spin-Qubit Device with a High Impedance Resonator Charlotte Boettcher, Shannon Harvey, Lucas Orona, Amir Yacoby Developing a hybrid spin-qubit-resonator system is appealing because it enables long distance coupling and a potentially faster two-qubit gate compared to a capacitive mediated qubit-interaction. However, it is challenging to implement because it requires fabrication techniques that are compatible with both high quality resonators and gateable heterostructures. We present our results using niobium nitrate nanowire kinetic inductors as resonators coupled to singlet-triplet qubits in GaAs. After optimizing fabrication steps, resonators with quality factors of over 5000 were achieved with impedances of several thousand. Measurements of a singlet-triplet qubit proximal to the resonator reveal tunable single qubits coupled to an adjacent resonator. We detect excitations of the resonator by measuring the qubit’s splitting as a function of the drive and frequency of a microwave signal applied near the resonator’s antinode and observe that qubit splitting is resonator-dependent. |
Thursday, March 8, 2018 12:03PM - 12:15PM |
S33.00003: A Superconducting 0-π Qubit Based on High Transmission Semiconductor-Superconductor Josephson Junctions Thorvald Larsen, Lucas Casparis, Anders Kringhøj, Natalie Pearson, Robert McNeil, Ferdinand Kuemmeth, Michael Gershenson, Peter Krogstrup, Jesper Nygard, Karl Petersson, Charles Marcus The 0-π qubit has been proposed as the fundamental building block of topologically protected qubits [1] that feature topologically protected gates [2]. Recent experiments have measured non-cosinusoidal energy-phase relations in high-transmission, semiconductor-superconductor Josephson junctions (JJ) in gatemon qubits [3,4]. Here we present measurements on a superconducting circuit architecture exploiting this non-cosinusoidal energy-phase relation to form a protected 0-π qubit [5]. Voltage control of the semiconductor JJ’s creates a unique superconducting qubit system allowing in situ tuning between widely different qubit regimes: transmon, flux, and 0-π qubit. Close to the 0-π regime we observe enhanced lifetimes indicating protected qubit states. |
Thursday, March 8, 2018 12:15PM - 12:27PM |
S33.00004: Gate-tunable Transmon Qubit made with Graphene/hBN Heterostructures Joel Wang, Daniel Rodan Legrain, Landry Bretheau, Fei Yan, Morten Kjærgaard, David Kim, Jonilyn Yoder, Gabriel Samach, Daniel Campbell, Philip Krantz, Kenji Watanabe, Takashi Taniguchi, Terry Orlando, Simon Gustavsson, Pablo Jarillo-Herrero, William Oliver Graphene – an atomic layer of carbon atoms arranged in a honeycomb lattice – can acquire superconductivity via the proximity effect. We present the fabrication and characterization of a transmon qubit using graphene as a voltage-tunable weak link. The graphene monolayer is encapsulated in hBN crystals from both sides and couples to aluminum electrodes via etched 1-D edges to ensure highly transparent contacts. The critical supercurrent of the S-G-S junction is tuned by an underlying back-gate fabricated on the qubit chip. Using standard dispersive readout techniques, we observe that the frequency and coherence of our qubit exhibit an evident dependence on the Fermi energy – controlled by the back-gate – as expected for graphene weak links. Our result opens a new avenue toward voltage-controlled superconducting qubits, with relevance to certain scalable quantum computing concepts, as well as a novel platform to study mesoscopic physics using circuit QED techniques. |
Thursday, March 8, 2018 12:27PM - 12:39PM |
S33.00005: Dissipative and dispersive dynamics of a transmon qubit in a superconducting metamaterial Mohammad Mirhosseini, Eunjong Kim, Alp Sipahigil, Mahmoud Kalaee, Vinicius Ferreira, Andrew Keller, Oskar Painter
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Thursday, March 8, 2018 12:39PM - 12:51PM |
S33.00006: Superconducting resonator pair coupled to common two-level systems through an electrical bridge Neda Forouzani, Bahman Sarabi, Omid Noroozian, Edward J. Wollack, Samuel H. Moseley, Frederick Wellstood, Kevin Osborn Atomic two level system defects (TLSs) are ubiquitous in superconducting quantum information processing devices and astronomy photon detectors, and therefore an understanding of them in new devices is of technological importance. We have developed a pair of resonators using the four nodes of an electrical bridge capacitance. This capacitor configuration allows the two resonators to share common TLSs in separately addressable resonator modes. The TLSs are within a deposited film of dielectric within the capacitors. One resonator from the pair is designed with a tunable inductor made from titanium nitride. It allows a relatively large frequency tuning range, up to 120 MHz, through application of a DC current. This design allows us to study virtually TLSs with nearly degenerate resonators. We will report on the degree to which resonator quality factor is limited by the TLSs. |
Thursday, March 8, 2018 12:51PM - 1:03PM |
S33.00007: Permanent spin currents in cavity-qubit systems Camille Aron, Sven Hein, Eliot Kapit, Manas Kulkarni In a recent remarkable experiment [P. Roushan et al, Nature Physics 13, 146 (2017)], a spin current in an architecture of three superconducting qubits was produced during a few microseconds by creating synthetic magnetic fields. The life-time of the current was set by the typical dissipative mechanisms that occur in those systems. We propose a scheme for the generation of permanent currents, even in the presence of such imperfections, and scalable to larger system sizes. It relies on striking a subtle balance between multiple nonequilibrium drives and the dissipation mechanisms, in order to engineer and stimulate chiral excited states which can carry current. |
Thursday, March 8, 2018 1:03PM - 1:15PM |
S33.00008: Electronic zero-point fluctuation forces inside circuit components Ephraim Shahmoon, Ulf Leonhardt One of the most intriguing manifestations of quantum zero-point fluctuations are the van der Waals and Casimir forces, often associated with vacuum fluctuations of the electromagnetic field. Here we study generalized fluctuation potentials acting on internal degrees of freedom of components in electrical circuits. These electronic Casimir-like potentials are induced by the zero-point current fluctuations of any general conductive circuit. For realistic examples of an electromechanical capacitor and a superconducting qubit, our results reveal the possibility of tunable forces between the capacitor plates, or the level shifts of the qubit, respectively. Our analysis suggests an alternative route towards the exploration of Casimir-like fluctuation potentials, namely, by characterizing and measuring them as a function of parameters of the environment. |
Thursday, March 8, 2018 1:15PM - 1:27PM |
S33.00009: Superconducting Qubits Coupled to Propagating Magnons Arjan Van Loo, Sandoko Kosen, Richard Morris, Alexy Karenowska Over the last few years, there has been significant experimental effort in coupling superconducting qubits to magnons. In most of those experiments, the coupling was between magnetostatic modes in an Yttrium Iron Garnet (YIG) sphere and a superconducting qubit, mediated via a 3D cavity [1]. Using propagating magnons instead of microwave photons to relay information and mediate interactions between qubits opens up a range of new experiments due to the different properties propagating magnons have compared to microwave photons [2]. Here, we focus on coupling superconducting qubits to propagating magnons in a YIG film. |
Thursday, March 8, 2018 1:27PM - 1:39PM |
S33.00010: Device Criteria for Accurate Single Electron Pumping Roy Murray, Justin Perron, M. Stewart Jr., Neil Zimmerman Pumping electrons for both quantum information and metrological purposes is of great interest. Minimizing errors in moving electrons is very important for both fields. A variety of designs and operating modes for transferring electrons in these tunable barrier pumps has been pursued, utilizing one or more AC signals. Different operating modes have different demands on device performance, but there are some general rules to device design. Criteria such as gate-gate capacitance, gate-dot capacitance, barrier steepness, charging energy and temperature are the most important. Here we present results, using basic principles and experimental data, on designing and operating a tunable barrier CMOS charge pump. We will cover device requirements for low error charge pumping using a variety of modes, and present pumping results of a device operating in each of the presented modes. |
Thursday, March 8, 2018 1:39PM - 1:51PM |
S33.00011: Coherent Transmon-Charge Qubit Coupling Mediated by Virtual Photon Exchange in a High Impedance Resonator. Pasquale Scarlino, David Van Woerkom, Udson Mendes, Simone Gasparinetti, Jonne Koski, Andreas Landig, Christian Reichl, Werner Wegscheider, Thomas Ihn, Klaus Ensslin, Alexandre Blais, Andreas Wallraff We explore the coupling of the charge degree of freedom of electrons confined in a GaAs/AlGaAs double quantum dot (DQD) to a superconducting transmon qubit in the circuit QED architecture. In this work, we realize a proof of concept experiment in which the coupling between a transmon qubit and a DQD qubit is mediated by virtual microwave photon excitations in a tunable high impedance SQUID array resonator, which acts as a quantum bus enabling long range coupling between dissimilar qubits. Our device hosts a DQD capacitively coupled to a SQUID array resonator, which in turn is coupled to a single island transmon. The device is further equipped with a flux line for fast control of the transmon frequency, and with a 50 Ω CPW resonator capacitively coupled to the transmon for readout. Realizing a well controlled interface between semiconductor and superconductor-based quantum computing architectures will allow to take full advantage of those two solid states quantum systems for hybrid-quantum processors and will enable the use of both charge and flux degrees of freedom in the same device. The methods and techniques developed in this work are expected to be transferable to other material systems. |
Thursday, March 8, 2018 1:51PM - 2:03PM |
S33.00012: 1D InAs channels by selective area growth for topological superconductivity applications Joon Sue Lee, Sukgeun Choi, Mihir Pendharkar, Anthony McFadden, Chris Palmstrom Topological superconductivity has been realized using one-dimensional (1D) semiconductor nanowire-based systems. An important step towards topological quantum computation applications is to demonstrate complex nanostructures consisting of multiple 1D channels hosting the topological superconducting phases. Here, we demonstrate 1D in-plane InAs channels by selective-area growth on SiO2-patterned InP substrates using chemical beam epitaxy and molecular beam epitaxy. This bottom-up approach of selective-area growth is promising for realizing the scalable networks of 1D semiconductor channels. We investigated the optimal growth conditions of epitaxial InAs on InP by varying V/III ratio, substrate temperature, and growth rate. The resulting surface morphology and the facet formation of InAs crystals also depend on the crystallographic orientation and dimensions of 1D channel. In addition to the growth studies, we also discuss the electronic transport properties of the selectively grown InAs channels in various growth conditions, orientations, and dimensions. |
Thursday, March 8, 2018 2:03PM - 2:15PM |
S33.00013: Quantum Annealing Machine based on Floating Gate Array Tetsufumi Tanamoto, Jun Deguchi Quantum annealing machines based on superconducting qubits, which have the potential to solve optimization problems faster than digital computers, are of great interest not only to researchers but also to the general public. Here, we propose a quantum annealing machine based on a semiconductor floating gate (FG) array. We theoretically derive an Ising Hamiltonian from the FG system in its single-electron region. Recent high-density NAND flash memories are subject to intrinsic obstacles that originate from their small FG cells. The number of electrons stored in each FG cell becomes smaller and can be countable. So we utilize the countable electron region to operate single-electron effects of FG cells. Second, in the conventional NAND flash memory, the high density of FG cells induces the problem of cell-to-cell interference through their mutual capacitive couplings. We derive the Ising interaction from this natural capacitive coupling. If a commercial 64 Gbit NAND flash memory is used, ideally we expect it to be possible to construct 2 megabytes (MB) entangled qubits by using the conventional fabrication processes in the same factory as is used for manufacture of NAND flash memory. |
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