Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session P28: Superconducting Qubit Systems IILive
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Sponsoring Units: DQI Chair: David McKay |
Wednesday, March 17, 2021 3:00PM - 3:12PM Live |
P28.00001: Exploiting real-time classical resources in a quantum algorithm Antonio Corcoles, Maika Takita, Ken Inoue, Scott Lekuch, Zlatko Minev, Jerry Chow, Jay M Gambetta Quantum computing systems have reached a level of maturity over the last few years that allowed many algorithmic demonstrations and have triggered new advances, both theoretical and experimental. For superconducting qubits, there has recently been an increased focus on the development of classical control electronics towards the acquisition and processing of signals on time scales commensurate with the lifetimes of the qubits. This aspect of the technology is critical for the successful execution of some protocols that reside at the core of quantum information processing, like quantum error correction or adaptive versions of the quantum phase estimation algorithm. In this talk we present a demonstration of how this real-time classical computing can improve the results of a quantum algorithm executed on a system of superconducting qubits. |
Wednesday, March 17, 2021 3:12PM - 3:24PM Live |
P28.00002: Characterization of Superconducting Quantum Transmission Line Metamaterials Tamin Tai, Jingnan Cai, Steven M Anlage The design, fabrication and microwave characterization of capacitive coupled aluminum (Al) coplanar waveguide (CPW) resonators are investigated. Microwave characterization is carried out through their power dependence, DC magnetic field dependence and temperature dependence of resonant properties. All of the Al resonators deposited on sapphire or silicon substrates showed the expected resonance modes, power dependent dissipation, DC field dependent and temperature dependent lossy behaviors. Unusual switching between states at high RF field is observed, probably due to two level system state switching at high power. The other loss mechanisms such as quasi-particles, and vortices moving in these half wavelength resonators, have also been studied. By coupling and manipulating three junction flux qubits in these resonators, one expects to explore fundamental aspects of artificial materials (meta-atoms) and study the collective behavior of a quantum metamaterial system. |
Wednesday, March 17, 2021 3:24PM - 3:36PM Live |
P28.00003: Quantum control of cavities using an improved SNAP protocol without coherent errors Jonas Landgraf, Thomas Foesel, Florian Marquardt Superconducting microwave cavities provide high coherence times, enable flexible manipulation of quantum states and are thus a promising platform for quantum information processing. In this setup the selective number-dependent arbitrary phase (SNAP) gates [1] form an important class of gates, which can impart arbitrarily chosen phases to the different Fock states of the cavity. |
Wednesday, March 17, 2021 3:36PM - 3:48PM Live |
P28.00004: Single Flux Quantum-Based Superconducting Qubit Control and Quasiparticle Mitigation: Part I Andrew Ballard, Vito M Iaia, Tianna A. McBroom, Yebin Liu, Kenneth Dodge, Jaseung Ku, Chuan-Hong Liu, Alexander M Opremcak, Chris Wilen, Edward M Leonard, Matthew A Beck, Sohair Abdullah, Jonathan L DuBois, Dan Schmidt, Tammy Lucas, Michael R Vissers, John Biesecker, David Olaya, Manuel Castellanos-Beltran, Peter Hopkins, Joel N Ullom, Samuel P Benz, Robert McDermott, Britton Plourde Superconducting qubits are an attractive candidate for building quantum information processors. However, existing control techniques do not scale well to large multi-qubit arrays. A promising candidate for scalable control is the Single Flux Quantum (SFQ) digital logic family. In an initial single-chip implementation, the fidelity of SFQ-based qubit gates was limited by quasiparticle (QP) poisoning of the qubit. QP excitations created from the operation of the SFQ circuitry can be a source of decoherence and temporal instability in the qubit. In order to suppress QP poisoning, we have developed a multi-chip module with an SFQ driver on a classical control chip that is flip-chip coupled to a superconducting transmon qubit on a separate quantum chip. We characterize the QP poisoning in these structures and compare with earlier measurements on single-chip implementations of SFQ-based qubit control. We also discuss strategies for further mitigation of QP poisoning, including superconducting bandgap engineering. |
Wednesday, March 17, 2021 3:48PM - 4:00PM Live |
P28.00005: Single Flux Quantum-Based Superconducting Qubit Control and Quasiparticle Mitigation: Part 2 Chuanhong Liu, Alexander M Opremcak, Chris Wilen, Edward M Leonard, Matthew A Beck, Sohair Abdullah, Andrew Ballard, Vito M Iaia, Tianna A. McBroom, Yebin Liu, Kenneth Dodge, Jaseung Ku, David Olaya, Dan Schmidt, Tammy Lucas, John Biesecker, Manuel A Castellanos-Beltran, michael R. vissers, Peter Hopkins, Joel N Ullom, Samuel P Benz, Jonathan L DuBois, Britton Plourde, Robert F McDermott The Single Flux Quantum (SFQ) digital logic family has been proposed as a scalable approach for the control of next-generation multiqubit arrays. In an initial implementation, the fidelity of SFQ-based qubit gates was limited by quasiparticle (QP) poisoning induced by the dissipative SFQ driver. Here we introduce superconducting bandgap engineering as a mitigation strategy to suppress QP poisoning in this system. We explore low-gap moats and high-gap fences surrounding the qubit structure, along with a geometry involving extensive coverage of the high-gap groundplane with low-gap traps. We use charge-sensitive transmon qubits to evaluate the effectiveness of the various mitigation strategies in experiments involving direct QP injection. |
Wednesday, March 17, 2021 4:00PM - 4:12PM Live |
P28.00006: Integrated cavity parametric amplifier for qubit readout in 3D circuit QED architecture Zhixin Wang, Jayameenakshi Venkatraman, Xu Xiao, Shantanu O Mundhada, Volodymyr Sivak, Shyam Shankar, Michel Devoret High-performance qubit readout is essential for quantum information machines as well as for fundamental physics experiments on quantum measurements. In circuit quantum electrodynamics (cQED) systems, superconducting qubits are read out by monitoring the qubit-state-dependent phase shift of a microwave tone, which then passes through a quantum-limited parametric amplifier before being processed by classical electronics. In this configuration, readout efficiency is mainly limited by loss between the readout microwave resonator and the parametric amplifier. Here we introduce a new design in which the latter is placed into the former—a symmetric superconducting artificial "molecule" housed in a 3D readout cavity that contains both the qubit and the quantum-limited parametric amplifier to read it out. This layout should improve the signal-to-noise ratio while minimizing spurious measurement back-action caused by intra-cavity photons. Preliminary results will be presented. |
Wednesday, March 17, 2021 4:12PM - 4:24PM Live |
P28.00007: Protocols for robust generation of microwave photonic graph states from superconducting qubits Chenxu Liu, Edwin Barnes, Sophia Economou We present protocols that use superconducting qubits for robust generation of microwave photon cluster and graph states. The generated highly entangled states can be tailored to various quantum information processing tasks, such as robust quantum communication and entanglement generation between different modules of a distributed superconducting qubit processor. |
Wednesday, March 17, 2021 4:24PM - 4:36PM Live |
P28.00008: Probing nonlinear photon scattering with artificial atoms coupled to a slow-light waveguide Marco Scigliuzzo, Giuseppe Calajò, Francesco Ciccarello, Daniel Perez Lozano, Andreas Bengtsson, Pasquale Scarlino, Andreas Wallraff, Per Delsing, Simone Gasparinetti Engineering the electromagnetic environment of a quantum emitter makes it possible to observe a plethora of exotic physical phenomena involving atom-light interactions. In particular, coupling quantum emitters to a finite-band waveguide, leads to the formation of long-lived atom-photon bound states with energy outside the photonic band, recently observed in experiments. Here, going beyond linear optics response, we experimentally probe these bound states through a nonlinear scattering process. |
Wednesday, March 17, 2021 4:36PM - 4:48PM Live |
P28.00009: Dynamical decoupling in two-qubit interactions Jiawei Qiu, Yuxuan Zhou, Jiahao Yuan, Libo Zhang, Weiyang Liu, Song Liu, Fei Yan Tunable coupler enables new degrees of freedom in controlling qubits, meanwhile it introduces an additional decohering channel. In this talk, we demonstrate extending dynamical decoupling techniques to a multiqubit system including a tunable coupler, successfully suppressing low-frequency noise and elongating decoherence time. Various dynamical-decoupling sequences including spin echo, CPMG and PDD are implemented. In particular, PDD sequences are effective in correcting pulse errors as well. Noise analysis shows flux noise in our system has a 1/f spectrum plus additional low frequency components. |
Wednesday, March 17, 2021 4:48PM - 5:00PM Live |
P28.00010: Adiabatic controlled-phase gate with fixed-frequency qubits enabled by tunable coupler Ji Chu, Fei Yan
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Wednesday, March 17, 2021 5:00PM - 5:12PM Live |
P28.00011: MIRROR, MIRROR: Landau-Zener-Stückelberg-Majorana interferometry of a superconducting qubit in front of a mirror Ping Yi Wen, Oleh Ivakhnenko, Mikhail Nakonechnyi, Baladitya Suri, J. -J Lin, W. -J Lin, Jeng-Chung Chen, Sergey Shevchenko, Franco Nori, Io Chun Hoi We investigate the Landau-Zener-Stückelberg-Majorana (LZSM) interferometry of a superconducting qubit in a semi-infinite transmission line terminated by a mirror. We tune the resonant frequency of the transmon-type qubit into a node of the electromagnetic (EM) field, “hiding” from the EM field. We modulate the resonant frequency of the qubit by applying a sinusoidal flux pump through on-chip flux line and performing spectroscopy by measuring the reflection coefficient of a weak probe in the system. Remarkable interference patterns emerge in the spectrum, which can be interpreted as multiphoton resonances in the dressed qubit. The multiphoton resonances are up to the fourth order. Our calculations agree well with the experiments. |
Wednesday, March 17, 2021 5:12PM - 5:24PM Live |
P28.00012: Waveguide Quantum Electrodynamics with Superconducting Artificial Giant Atoms Bharath Kannan, Max J Ruckriegel, Daniel L Campbell, Anton Frisk Kockum, Jochen Braumueller, David K Kim, Morten Kjaergaard, Philip Krantz, Alexander Melville, Bethany Niedzielski, Antti Vepsäläinen, Roni Winik, Jonilyn Yoder, Franco Nori, Terry Philip Orlando, Simon Gustavsson, William Oliver Models of light-matter interactions typically invoke the dipole approximation, within which atoms are treated as point-like objects when compared to the wavelength of the electromagnetic modes that they interact with. However, when the ratio between the size of the atom and the mode wavelength is increased, the dipole approximation no longer holds and the atom is referred to as a "giant atom". Here, we realize giant atoms by coupling small atoms to a waveguide at multiple, but well separated, discrete locations. Our realization of giant atoms enables tunable atom-waveguide couplings with large on-off ratios and a coupling spectrum that can be engineered by device design. We also demonstrate decoherence-free interactions between multiple giant atoms that are mediated by the modes in the waveguide-- an effect that is not possible to achieve with small atoms. |
Wednesday, March 17, 2021 5:24PM - 5:36PM Live |
P28.00013: Cancellation of unwanted ZZ interactions for cross-resonance gates by superconducting qubit engineering Roni Winik, Catherine Leroux, Agustin Di Paolo, Thomas Hazard, Ross Shillito, Antti Vepsalainen, Youngkyu Sung, Ziqiao Ao, Morten Kjaergaard, Jochen Braumueller, Mollie Schwartz, Kyle Serniak, David K Kim, Jonilyn Yoder, Alexander Melville, Bethany Niedzielski, Alexandre Blais, Simon Gustavsson, William Oliver Superconducting qubit architectures are susceptible to unwanted ZZ interactions that limit 2QB gate fidelities and introduce correlated errors. This unwanted ZZ interaction is especially harmful to the cross-resonance gate. In this talk, we augment the transmon-qubit architecture by introducing a new superconducting qubit similar to the transmon but with positive anharmonicity. We experimentally demonstrate how this new architecture allows the unwanted ZZ between two distinct qubits to be greatly reduced with respect to typical values for transmon-only devices, and how this can be further leveraged to achieve high fidelity gates. We discuss design considerations and show how this approach can be integrated for designing a large-scale device with reduced ZZ between all pairs of nearest neighbors qubits and negligible spectator-qubit effects. |
Wednesday, March 17, 2021 5:36PM - 5:48PM On Demand |
P28.00014: Electron shelving of a superconducting artificial atom Yen-Hsiang Lin, Nathanael Cottet, Haonan Xiong, Long B Nguyen, Vladimir Manucharyan Simultaneously maintaining high coherent stationary qubit and interacting with propagating photons is a fundamental problem in quantum technology. Conventional circuit quantum electrodynamics (cQED) introduce an extra far-detuned cavity mode to mediate high coherent qubit transition and enables a dispersive readout. Here we report experiment of a fluxonium artificial directly placed inside a matched one-dimensional waveguide. Without introducing extra degree of freedom, we apply the electron shelving idea and demonstrate a conditional fluorescence readout. Cycling the non-computational transition between ground and third excited states produces a microwave photon every 91 ns conditioned on the qubit ground state, while the qubit (transition between ground and first excited states) coherence time exceeds 50 us. The readout has a built-in quantum non-demolition property, allowing over 100 fluorescence cycles in agreement with a four-level optical pumping model. Our result introduces a resource-efficient alternative to cQED. It also adds a state-of-the-art quantum memory to the growing toolbox of waveguide QED. |
Wednesday, March 17, 2021 5:48PM - 6:00PM Live |
P28.00015: Broadband Microwave Isolation via Adiabatic Mode Conversion in Superconducting Coupled Transmission Lines Mahdi Naghiloo, Kaidong Peng, Yufeng Ye, Gregory Cunningham, Kevin O'Brien We propose a new scheme that combines parametric mode conversion and adiabatic techniques in a pair of coupled nonlinear Josephson junction transmission lines to realize broadband isolation without magnetic elements. The idea is to induce an effective unidirectional parametric coupling between two otherwise orthogonal modes of propagation and engineer the dispersion to have an adiabatic conversion between two modes. Our realistic analysis suggests more than 20 dB isolation over an octave of bandwidth (4-8 GHz) with less than 0.1 dB of insertion loss. Our scheme is compatible with the current superconducting qubit technology. We report on progress toward implementing this device. |
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