Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session C29: Superconducting Circuits: New Qubit Technologies and Design II |
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Sponsoring Units: DQI Chair: Chen Wang, University of Massachusetts Amherst Room: BCEC 162A |
Monday, March 4, 2019 2:30PM - 2:42PM |
C29.00001: Emergence of quasi-charge in an ultra-high-impedance superconducting circuit: Design Ray Mencia, Ivan Pechenezhskiy, Long Nguyen, Vladimir Manucharyan We introduce an ultra-high-impedance superconducting circuit where the role of phase difference across a Josephson junction is replaced by quasi-charge. This Hamiltonian is dual to that of the transmon, in which the kinetic energy term associated with the charging energy is replaced by the inductive energy. Our circuit consists of a small-area Josephson junction shunted by a large linear inductance exceeding one micro-Henry. In such a circuit, the sensitivity of the ground to the first excited state transition is virtually flux insensitive while the flux-tunability of the transitions to higher excited states is largely preserved. Proper circuit design and choice of the fabrication techniques enable the mitigation of the parasitic capacitance previously associated with such large shunting inductances. In this talk, we demonstrate how the device spectra can be adequately described by the dual Hamiltonian and show that the flux dispersion of the qubit transition is reduced down to less than 100 MHz across the entire flux quantum. We also put a limit on the loss tangent of the inductor to be 5×10-6. |
Monday, March 4, 2019 2:42PM - 2:54PM |
C29.00002: Emergence of quasi-charge in an ultra-high-impedance superconducting circuit: Experiment Ivan Pechenezhskiy, Ray Mencia, Long Nguyen, Vladimir Manucharyan We introduce an ultra-high-impedance superconducting circuit where the role of phase difference across a Josephson junction is replaced by quasi-charge. This Hamiltonian is dual to that of the transmon, in which the kinetic energy term associated with the charging energy is replaced by the inductive energy. Our circuit consists of a small-area Josephson junction shunted by a large linear inductance exceeding one micro-Henry. In such a circuit, the sensitivity of the ground to the first excited state transition is virtually flux insensitive while the flux-tunability of the transitions to higher excited states is largely preserved. Proper circuit design and choice of the fabrication techniques enable the mitigation of the parasitic capacitance previously associated with such large shunting inductances. In this talk, we demonstrate how the device spectra can be adequately described by the dual Hamiltonian and show that the flux dispersion of the qubit transition is reduced down to less than 100 MHz across the entire flux quantum. We also put a limit on the loss tangent of the inductor to be 5×10-6. |
Monday, March 4, 2019 2:54PM - 3:06PM |
C29.00003: Building Hamiltonians with Josephson Phase-Slip Qubits David Clarke, David Ferguson, Ryan J Epstein Tunable Josephson phase-slip qubits (JPSQs) present the possibility of constructing effective spin-1/2 Hamiltonians with arbitrary 2-local interactions using superconducting technology. Here, we discuss how this mapping is made, presenting a Pauli-operator breakdown of the current and voltage dipoles of a JPSQ along a qubit annealing path that allows for preparation and readout in addition to the engineered couplings. As an example of the possibilities inherent in these devices, we present a system of JPSQs that adiabatically encodes or decodes a logical qubit in a [[4,1,2]] Bacon-Shor code. |
Monday, March 4, 2019 3:06PM - 3:18PM |
C29.00004: Characterization of Josephson phase-slip qubits, part 1: device fundamentals Cyrus F. Hirjibehedin, Steven J. Weber, Gabriel O. Samach, David K Kim, Alexander Melville, Bethany M. Niedzielski, Danna Rosenberg, Jonilyn L Yoder, William D Oliver, Andrew James Kerman The Josephson phase-slip qubit (JPSQ) [1] is a superconducting circuit that emulates a vector quantum S=1/2 system, with an effective dipole moment nearly independent of applied field, even near zero. This makes JPSQs ideal for emulating vector spin interactions, such as non-Stoquastic +XX of interest for quantum annealing. We describe the design and operation of a JPSQ implementation. Using dispersive readout, we demonstrate the predicted periodic tuning with both flux and charge, and measure lifetimes in the microsecond regime. We also characterize the influence of charge jumps on the circuit’s operation. These results confirm the operating principles of the JPSQ and suggest that it could play an important role in a variety of quantum device architectures. |
Monday, March 4, 2019 3:18PM - 3:30PM |
C29.00005: Characterization of Josephson phase-slip qubits, Part 2: Annealing Robert Hinkey, Moe Khalil, Sergey Novikov, David Clarke, James I. Basham, Steven Disseler, Alexander Marakov, Jeffrey Grover, David K Kim, Zachary A Stegen, Alexander Melville, Bethany M. Niedzielski, Jonilyn Yoder, Daniel A Lidar, Kenneth M. Zick, David Ferguson Josephson phase slip qubits (JPSQs) have been identified as a promising qubit with which to build next-generation quantum annealers. These qubits have charge tunability through the Aharanov-Casher effect. This charge tuning is a signature of their ability to achieve “strong” non-stoquastic XX couplings with “strong” indicating couplings that are large relative to residual single qubit fields. This coupling regime is not known to be possible to achieve with conventional flux qubits. In this talk we present initial characterization measurements of JPSQs that are annealing-compatible and have a large charge dispersion. |
Monday, March 4, 2019 3:30PM - 3:42PM |
C29.00006: Classically reversible logic gate coupled to a superconducting qubit: Problem definition (pt. 1) Kevin Daniel Osborn, Waltraut Wustmann
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Monday, March 4, 2019 3:42PM - 3:54PM |
C29.00007: Classically reversible logic gate coupled to a superconducting qubit: Qubit simulation (pt. 2) Waltraut Wustmann, Kevin Daniel Osborn We theoretically study a classically reversible logic gate coupled to a superconducting qubit for potential applications in quantum computing. The classical gate consists of a Josephson junction circuit interface between long Josephson junctions, and the input of the gate is a ballistically traveling fluxon (a topological sine-Gordon soliton). Depending on the gate definition, a fluxon can undergo different types of resonant elastic scattering, e.g., forward scattering as fluxon or antifluxon. Here we report on how the scattering outcome can depend on the state of a qubit that is embedded in the interface, thus potentially allowing the readout of the qubit from the fluxon dynamics. We specifically will show the effect for a fluxonium qubit galvanically coupled through a junction in the gate interface. This presents a large 4pi-phase difference seen by the qubit. Different fluxon scatterings are found in the classical dynamics of the coupled system for the fluxonium qubit states with macroscopically different phases. We will further use a quantized version of a quasiparticle model, originally developed for classical gates, and take into account few fluxonium levels. The newer analysis should allow us to predict state evolution of a qubit strongly coupled to a topological soliton. |
Monday, March 4, 2019 3:54PM - 4:06PM |
C29.00008: Quantum information processing using 3D multimode circuit QED Srivatsan Chakram, Ravi Naik, Akash Dixit, Yao Lu, Alexander Anferov, Nelson Leung, Andrew Oriani, David Schuster Multimode superconducting microwave cavities provide a hardware efficient means of engineering a large, high-coherence Hilbert space suitable for quantum information processing. When coupled to a superconducting transmon circuit, they can be used to construct random access quantum processors in which logic gates can be performed between arbitrary pairs of cavity modes via sideband transitions with the transmon [1]. We present our progress toward realizing such a processor using a seamless rectangular 3D multimode cavity - the quantum flute, with a tailored mode dispersion and decay times around a millisecond for tens of cavity modes. To eliminate coherent errors arising from multimode state dependent Stark shifts of the transmon, we introduce an intermediate single-mode 'manipulate' cavity with a tunable coupling to the multimode cavity. |
Monday, March 4, 2019 4:06PM - 4:18PM |
C29.00009: Towards Developing a Graphene Josepheson junction based qubit device Kyle McElroy, Jesse E Thompson, Brandon T Blue, Lafe Spietz, Jacob Epstein, Masa Ishigami, Joan A Hoffmann Construction of Josepheson weak links is an integral part of superconducting quantum devices. New junction structures have various potential applications as new qubits or sensors. We will discuss the preliminary development of a transmon with a graphene based Josepheson junction. The devices are fabricated using epitaxially grown graphene, transferred to a sapphire base with standard lithographic techniques used for junction and antenna layout. The junctions are designed to have 0.3-0.85 nA critical currents and antenna geometry for device resonances between 2-6 GHz and are imbedded in a high Q 3D cavity at 7.7 GHz. |
Monday, March 4, 2019 4:18PM - 4:30PM |
C29.00010: Quantum coherent control of graphene-based transmon qubit Joel Wang, Daniel Rodan Legrain, Charlotte Boettcher, Landry Bretheau, Daniel Campbell, Bharath Kannan, David K Kim, Morten Kjærgaard, Philip Krantz, Gabriel O. Samach, Fei Yan, Jonilyn L Yoder, Kenji Watanabe, Takashi Taniguchi, Terry Philip Orlando, Simon Gustavsson, Pablo Jarillo-Herrero, William D Oliver Van der Waals (vdW) materials–a family of layered crystals with various functionalities, can be assembled in specific arrangements to create new electronic devices called vdW heterostructures. The extraordinary and versatile electronic properties of these heterostructures, in combination with their epitaxial precision, make vdW-based devices a promising alternative for constructing key elements of novel solid-state quantum computing platforms.We demonstrate quantum coherent control of a superconducting circuit incorporating graphene-based vdW heterostructures. We show that this device can be operated as a voltage-tunable transmon qubit, whose spectrum reflects the electronic properties of massless Dirac fermions traveling ballistically. In addition to the potential for advancing extensible quantum computing technology, our results represent a new approach to studying vdW materials using microwave photons in coherent quantum circuits.(arXiv:1809.05215) |
Monday, March 4, 2019 4:30PM - 4:42PM |
C29.00011: Resonator Cavities Compatible with Epitaxial InAs-Al Heterostructures Joseph Yuan, Matthieu Dartiailh, William Andrew Mayer, Eric Song, Kaushini Wickramasinghe, Javad Shabani Epitaxial Al-InAs structures are prime candidates for tunable superconducting qubits, the so-called |
Monday, March 4, 2019 4:42PM - 4:54PM |
C29.00012: Superconducting gatemon qubits based on selective-area-grown semiconductor materials Albert Hertel, Laurits Orheim Andersen, Natalie Pearson, Malcolm R Connolly, Valentina Zannier, Lucia Sorba, Liu Yu, Peter Krogstrup, Geoffrey C. Gardner, Michael Manfra, Karl D Petersson, Charles M Marcus Semiconductor-superconductor hybrid gatemon qubits offer a promising path to large scale quantum processors. In contrast to conventional transmon qubits that are controlled using currents, gatemons allow complete control using only gate voltages [1], potentially alleviating challenges to scaling superconducting qubits [2]. Here, we present a novel approach to building gatemons utilizing selective-area-grown InAs structures on an InP substrate [3,4]. This approach allows deterministic placement and straightforward fabrication of the gatemon qubits. We characterize the material and perform first proof-of-principle measurements to demonstrate coherent qubit oscillations. Further work is needed to understand the dominant loss mechanisms and improve coherence times. |
Monday, March 4, 2019 4:54PM - 5:06PM |
C29.00013: Control of topological properties in the Kitaev chain by quantum microwave radiation Fabio Méndez-Córdoba, Fernando Gómez-Ruiz, Juan Mendoza-Arenas, Ferney Rodriguez, Carlos Tejedor, Luis Quiroga We investigate observable signatures coming from the light-matter coupling of a Kitaev chain embedded in a microwave cavity. |
Monday, March 4, 2019 5:06PM - 5:18PM |
C29.00014: Ultra low-loss single-crystalline material platform for high-Q quantum devices Ilya Rodionov, Aleksandr Baburin, Ilya A. Ryzhikov, Aidar R. Gabidullin, Dmitriy O. Moskalev, Alina Dobronosova, Alexey Matanin Quantum technologies is a rapidly grown research area, which have the potential to lead the revolution in supercomputing, sensing, global communications and security. The leading quantum computing concepts of design like superconductive qubits, optical quantum computing devices, solid-state and hybrid quantum systems are based on traditional semiconductor technology platform. However, new materials and nanoscale structures fabrication techniques are needed to explore the underlying physics and fulfill the subsequent specifications. Losses in thin films, surface, structure and interfaces quality are coming into the fore. |
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