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 E30: Fabrication and Device Design of Superconducting QubitsLive
|
Hide Abstracts |
Sponsoring Units: DQI Chair: Mollie Schwartz, MIT Lincoln Lab |
Tuesday, March 16, 2021 8:00AM - 8:12AM Live |
E30.00001: Superconducting qubits containing through-silicon vias Thomas Hazard, Mollie Schwartz, Wayne Woods, Danna Rosenberg, Kyle Serniak, Rabindra Das, David K Kim, Jeffrey M Knecht, Justin L Mallek, Alexander Melville, Bethany Niedzielski, Donna-Ruth Yost, Jonilyn Yoder, William Oliver Superconducting qubits are a promising candidate for quantum computing applications. As the number of qubits in small quantum processors increases, the relatively large size of each qubit creates new engineering challenges. Small form factor superconducting through-silicon vias (TSVs) -- originally developed for high density input/output capabilities – can be incorporated into a qubit circuit in order to reduce the qubit's size. We discuss the design, fabrication, and performance of qubits that leverage the large capacitance density of our compact TSVs. |
Tuesday, March 16, 2021 8:12AM - 8:24AM Live |
E30.00002: The Most Coherent Superconducting Qubit? Aaron Somoroff, Quentin Ficheux, Ray Mencia, Haonan Xiong, Konstantin Nesterov, Maxim G Vavilov, Vladimir Manucharyan Highly anharmonic artificial atoms present a promising approach to gate-based quantum computing. We report our progress in improving coherence and control of fluxonium superconducting circuits with enhancements in fabrication [1]. We demonstrate a device with coherence time T2 exceeding 1 millisecond and an average single qubit gate fidelity greater than 99.99%. Importantly, our circuits are fabricated with robust and scalable methods compatible with existing CMOS manufacturing. This coherence time is still limited by dielectric loss and can be improved further by mitigating material losses. Finally, we discuss the implications of this result on scaling up these devices to quantum processors [2]. |
Tuesday, March 16, 2021 8:24AM - 8:36AM Live |
E30.00003: Fabrication methods for high-coherence and scalable fluxonium qubits Jin Qin, Ran Gao, Feng Bao, Hao Deng, Hsiang-Sheng Ku, Xun Jiang, Zhisheng Li, Xiaotong Ni, Zhijun Song, Hantao Sun, Chengchun Tang, Tenghui Wang, Feng Wu, Wenlong Yu, Tian Xia, Gengyan Zhang, Xiaohang Zhang, Jingwei Zhou, Xing Zhu, Hui-Hai Zhao, Chunqing Deng A practical superconducting quantum computer requires a large number of physical qubits with high operation fidelity. The fluxonium qubit, where a Josephson junction is shunted by a super-inductor made of a junction array, can achieve both long coherence time and high gate speed, which ultimately leads to high-fidelity operations. However, wafer-scale fabrication is challenging as the current Josephson junction fabrication techniques rely heavily on the precise control of resist thicknesses and evaporation angles. Here, we report a junction fabrication method to achieve wafer-scale junction array fabrication with a Manhattan-style design. Such a junction design has a limited dependence on process variations and precise parameter control at wafer-scale. At the same time, through integrating high-quality materials like TiN and Tantalum, increased coherence times are observed, which paves the way for high-fidelity multiple-qubit processors based on fluxonium. |
Tuesday, March 16, 2021 8:36AM - 8:48AM Live |
E30.00004: Development of the quantum processing units (QPUs) at IQM Finland Oy Wei Liu, Tianyi Li, Manjunath Venkatesh, Chun Fai Chan, Fabian Marxer, Mate Jenei, Lily Yang, Vasilii Sevriuk, Hasnain Ahmad, Roope Kokkoniemi, Kristinn Juliusson, Jari Penttilä, Janne Kotilahti, Johannes Heinsoo, Caspar Ockeloen-Korppi, Jean-Luc Orgiazzi, Jayanta Sarkar, Pasi Lähteenmäki, Kok Wai Chan, Juha Hassel, Jorge Tiago Santos, Jan Goetz, Juha Vartiainen, Mikko Möttönen, Kuan Yen Tan Realizing large-scale quantum computers is one of the most important goals of science and technology today. It will revolutionize computing technology and push the boundaries of all fields of science. As a spinout from Aalto University and VTT, IQM focuses on the realization of a quantum computer based on superconducting circuits. Here, we present the fabricated devices and results achieved to date, which includes resonators with high-quality factors > 2e6, long qubit lifetime > 0.07 ms, and 3D integration techniques such as airbridges. |
Tuesday, March 16, 2021 8:48AM - 9:00AM Live |
E30.00005: Mode Hybridization and Radiative Properties of an Artificial Atom coupled to a Josephson Junction Array Kanupriya Sinha, Saeed Khan, Hakan E Tureci We study the radiative properties of an artificial atom coupled to a Josephson junction array (JJA). Using a normal mode analysis of the system, we classify two regimes of weak and strong hybridization between the atomic and JJA modes based on their effective coupling strengths. In the weak hybridization regime we find a distinct spatially localized atomic mode both when the atomic frequency lies within and outside of the photonic band. However, for strong atom-JJA hybridization there is no such localized mode within the band. In this regime concepts such as spontaneous emission and Lamb shift are not well-defined as this situation represents a case of non-perturbative 1+1D quantum electrodynamics. We present a theoretical framework that replaces perturbative descriptions of radiative corrections, bridging the perturbative and the non-perturbative limits. |
Tuesday, March 16, 2021 9:00AM - 9:12AM Live |
E30.00006: Fast qubit resetting with a quantum-circuit refrigerator Timm Mörstedt, Giacomo Catto, Arto Viitanen, Tianyi Li, Wei Liu, Joni Ikonen, Vasilii Sevriuk, Jan Goetz, Máté Jenei, Matti Silveri, Matti Partanen, Leif Grönberg, Visa Vesterinen, Gianluigi Catelani, Tapio Ala-Nissila, Mikko Möttönen Superconducting qubits have emerged as powerful building blocks for a quantum computer. However, precise reset of qubits into their ground states remains a challenge. Although qubits naturally relax, this process is slow for high-coherence qubits and eventually inhibits fast computing. A way forward is provided by a voltage-tunable quantum-circuit refrigerator (QCR), a microcooler based on photon-assisted electron tunneling in a pair of NIS junctions. Here, we present an experimental realization of a QCR coupled to a transmon qubit as well as its optimization for fast on-demand qubit reset. |
Tuesday, March 16, 2021 9:12AM - 9:24AM Live |
E30.00007: Photon-Number-Dependent Effective Lamb Shift Induced by a Radio-Frequency Quantum-Circuit Refrigerator Mikko Mottonen, Arto Viitanen, Matti Silveri, Máté Jenei, Vasilii Sevriuk, Kuan Yen Tan, Matti Partanen, Jan Goetz, Leif Grönberg, Valtteri Lahtinen The Lamb shift, an energy shift arising from the presence of the electromagnetic vacuum, has been observed in various quantum systems and established as the part of the energy shift independent of the environmental photon number. However, typical studies are based on simplistic bosonic models and may be challenged in practical quantum devices. We demonstrate [1] a hybrid bosonic-fermionic environment for a linear-resonator mode and observe that the photon number in the environment can dramatically increase both the dissipation and the effective Lamb shift of the mode. Our observations are quantitatively described by a first-principles model which we develop here also to guide device design for future quantum-technological applications. Importantly, the device demonstrated here can be utilized as a fully rf-operated quantum-circuit refrigerator [2] to quickly reset superconducting qubits or other electric quantum devices of interest. |
Tuesday, March 16, 2021 9:24AM - 9:36AM Live |
E30.00008: Superconducting circuits for probing quantum materials Ruichao Ma, Jeremy Cadiente, Botao Du, Gozde Iloglu Advances in quantum technologies greatly rely on progress in quantitative understanding of material properties. Here we focus on probing coherent properties and decoherence channels of existing and new materials using superconducting quantum circuits – capitalizing on the precise control and detection of microwave photons offered by the circuit QED toolbox. I will describe our progress towards realizing a transmon-like qubit fabricated with superconductor-topological insulator-superconductor junctions. Spectroscopic and time-domain measurements of the TI-transmon could reveal coherent transport properties of the TI material at the single quantum level, and provide a general recipe for studying other quantum materials in the circuit platform. I will also briefly discuss other research efforts in our lab on analog quantum simulation of synthetic quantum materials using superconducting circuits. |
Tuesday, March 16, 2021 9:36AM - 10:12AM Live |
E30.00009: Fabrication Control of Superconducting Qubit Devices Invited Speaker: Bethany Niedzielski Superconducting qubits with Josephson junction elements are gaining traction as a key modality towards the realization of a quantum computer. These devices have transitioned from scientific discovery to device optimization as the materials, fabrication processes, designs, and measurement capabilities are maturing. Precise control of junction parameters is needed for ideal device performance, especially as system sizes and complexity grow. Motivated by device coherence times, I will discuss our work to understand and control the uniformity of Josephson junctions in the size range best suited for device performance. |
Tuesday, March 16, 2021 10:12AM - 10:24AM Live |
E30.00010: Dynamics of superconducting qubit relaxation Malcolm Carroll, Sami Rosenblatt, Abhinav Kandala Single junction transmon qubits are a leading candidate for quantum computing, in part, because of their robustness to charge and flux noise. However, they display large temporal fluctuations in their energy relaxation times T1. This introduces challenges to the stability of multi-qubit device performance. Furthermore, averaging over days or weeks can also be necessary to obtain representative measures of T1 for process optimization and device screening. These T1 fluctuations are typically attributed to resonant couplings of the qubit to two level systems (TLS). In this work, we probe the spectral and temporal dynamics of T1 in single junction transmons by measurements of relaxation probabilities at AC-Stark shifted frequencies around the bare transition. Across 10 qubits, we observe strong correlations between the relaxation probability averaged around the bare qubit frequency, and mean T1 averaged over several months. This suggests that the qubits sample an ergodic-like spectral diffusion of the nearby TLSs and that the long-time average T1 might be estimated rapidly from a snapshot of its frequency dependence. |
Tuesday, March 16, 2021 10:24AM - 10:36AM Live |
E30.00011: Exciting qubits and excited quasiparticles: the effect of actively pumping a qubit on its environment Niv Drucker, Martin Spiecker, Daria Gusenkova, Francesco Valenti, Ivan Takmakov, Patrick Winkel, Alexey Ustinov, Wolfgang Wernsdorfer, Yonatan Cohen, Ioan-Mihai Pop, Richard Gebauer, Nick Karcher, Denis Rieger, Oliver Sander In recent years, sophisticated control schemes for exploring and, moreover, reducing noise in quantum devices are being heavily investigated. Two important noise mechanisms in superconducting circuits that are being explored extensively and for which such control schemes have been employed, are quasiparticle tunneling and two-level systems. Here we shed more light on the subject by utilizing the Quantum Orchestration Platform, a unique control platform that provides ultra-low-latency feedback and great programming flexibility, to carefully design control sequences and explore their effect on the quasiparticle environment of a superconducting fluxonium qubit. We show striking results that demonstrate a highly non-linear environment with non-exponential and very low decay rates. |
Tuesday, March 16, 2021 10:36AM - 10:48AM Live |
E30.00012: Sub-Kelvin Thermometer for On-Chip Measurements of Microwave Devices Utilizing Two-Level Systems in Superconducting Microresonators Jordan Wheeler, michael R. vissers, Maxime Malnou, Jiansong Gao, Johannes Hubmayr, Joel N Ullom Two-level systems (TLS) are well-known to be a source of decoherence in superconducting qubits. Extensive research has been carried out to understand its physics and to mitigate its negative effects. In this talk, however, we describe how to make use of TLS physics to create a useful device. We present a superconducting microresonator thermometer based on the TLS-induced frequency shift that is drop-in compatible with cryogenic microwave systems such as qubits. The operational temperature range is 50-1000 mK (which may be extended to 5 mK). The miniature footprint can be conveniently attached to the feedline of the microwave devices. The key advantage is that it enables easy and accurate measurement of the true chip temperature without additional wiring or readout electronics. We demonstrate the practical use of these TLS thermometers to investigate static and transient chip heating in a kinetic inductance traveling-wave parametric amplifier (KIT) operated with a strong pump tone. We describe how the insights from these temperature measurements have guided us to the successful mitigation of excess thermal loads in our cryogenic testbed. TLS thermometry may find broad applications for use with superconducting qubit and detector systems. |
Tuesday, March 16, 2021 10:48AM - 11:00AM Live |
E30.00013: Flux Qubits Fabricated using a High-Coherence Transmon Fabrication Process Trevor Chistolini, William Livingston, John Mark Kreikebaum, David Ivan Santiago, Irfan Siddiqi The coherence of superconducting circuit qubits has dramatically improved since initial implementations, leaping from T1 ~1 ns in early Cooper pair boxes to now attaining ~100 μs in transmons. Much of this improvement has involved careful electromagnetic design paired with fabrication and material research. Our in-house fabrication protocol has been previously optimized for transmons, and we now apply these methods to flux qubits. Numerical simulations were performed to investigate the flux qubit energy spectrum, qubit-resonator coupling, and noise susceptibility to inform design parameters. After optimizing the fabrication process, we present work investigating flux qubits in 3D cavities, in addition to an 8-qubit ring of alternating flux qubits and transmons with nearest neighbor coupling. We perform initial investigations into two-qubit gates between flux qubits and transmons of opposing anharmonicity. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700