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 E33: Noise Reduction and Error Mitigation in Quantum Computing IIILive
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Sponsoring Units: DQI Chair: Stanley Steers, Northrop Grumman - Mission Systems |
Tuesday, March 16, 2021 8:00AM - 8:12AM Live |
E33.00001: Generalized Markovian Noise as a Resource for Suppressing Markovian Errors in Superconducting Qubits: Part II (Experiment) Haimeng Zhang, Evangelos Vlachos, Jeffrey Marshall, Tameem Albash, Eli Levenson-Falk In superconducting qubits, non-Markovian noise environments, i.e. environments with non-negligible memory effect and temporal correlation, are often considered harmful to quantum computational tasks. Recent theoretical work has predicted that non-Markovian environments can also be used to reduce error rates. We experimentally test how non-Markovian noise can be used as a resource to suppress Markovian dephasing noise in a transmon qubit. Theory predicts that by injecting classical non-Markovian noise, the qubit dephasing time can be extended. The best dephasing noise suppression can be achieved by choosing an optimal memory kernel function of the non-Markovian noise, as predicted by our quantum trajectory simulations and the master equation description (see Part I of this talk). We discuss the implications of our results on correlations in non-Markovian noise and how they provide an extra degree of freedom in controlling and engineering qubit dissipation process. We further discuss how, comparing with other deterministic control sequences, our noise suppression protocol, being stochastic in nature, is potentially more flexible in design and more robust to control errors. |
Tuesday, March 16, 2021 8:12AM - 8:24AM Live |
E33.00002: Characterization of Time-Correlated Semiclassical Control Noise of IBM Transmon Qubits Robert Barr, Colin Trout, Yasuo Oda, Greg Quiroz, Kevin Schultz, Paraj Titum, Leigh M Norris, Lorenza Viola, David Clader Precise and robust control of quantum systems is a requirement for many proposed quantum technologies spanning fields from quantum metrology to quantum computing. The major roadblock in precise and robust quantum control of quantum systems is the noise introduced by unwanted interactions between the quantum states and its environment. To design optimal control sequences which counter the noise, it is first necessary to have a high-accuracy characterization of the statistical properties of the noise. In this work, we apply provably optimal narrowband quantum control sequences to probe fine spectral features of both native and injected control noise on IBM’s transmon-based qubits using the OpenPulse framework. Our approach is founded on an adaptation of classical multitaper spectral analysis to the quantum realm [1]. |
Tuesday, March 16, 2021 8:24AM - 8:36AM Live |
E33.00003: A Josephson traveling wave parametric amplifier featuring superconducting nonlinear asymmetric inductive elements. Visa Vesterinen, Debopam Datta, Nils Tiencken, Slawomir Simbierowicz, Robab Najafi Jabdaraghi, Leif Grönberg, Janne Lehtinen, Mika Prunnila, Joonas Govenius We present our latest experimental results on Josephson traveling wave parametric amplifiers (TWPAs) fabricated with our Nb/Al-AlOx/Nb junction process [1,2] tailored for the readout of superconducting quantum bits. Our TWPA exhibits gain in excess of 15 dB across 4-9 GHz in three-wave mixing. The device design features superconducting nonlinear asymmetric inductive elements (SNAILs), an integrated on-chip magnetic flux bias line, as well as engineered dispersion for the control of the second harmonic generation of the pump tone. We compare the experimental results to predictions from coupled mode equations. |
Tuesday, March 16, 2021 8:36AM - 8:48AM Live |
E33.00004: Modeling and mitigation of realistic readout noise with applications to Quantum Approximate Optimization Algorithm Filip Maciejewski, Flavio Baccari, Zoltán Zimborás, Michal Oszmaniec We introduce a correlated measurement noise model that can be efficiently described and characterized, and which admits noise-mitigation on the level of marginal probability distributions. Noise mitigation can be performed up to some error for which we give upper bounds. Characterization of the model is done efficiently using a generalization of Quantum Overlapping Tomography. We perform experiments on up to 15 qubits on IBM’s and Rigetti's quantum devices to test error-mitigation and conclude significant improvements. Furthermore, we study the effects of readout noise on the performance of the Quantum Approximate OptimizationAlgorithm (QAOA). We observe numerically that for numerous objective Hamiltonians, our noise-mitigation improves the quality of optimization in QAOA. Finally, we provide arguments why in the estimation of energy of local Hamiltonians that typically appear in QAOA, estimated variables (energies of local terms) can be expected to effectively behave as uncorrelated for a broad class of states. Those include states appearing in QAOA, Haar-random quantum states, and states generated by random shallow circuits. |
Tuesday, March 16, 2021 8:48AM - 9:00AM Live |
E33.00005: Quantum error mitigation in the presence of time-correlated noise Kevin Schultz, Gregory Quiroz, Yasuo Oda, Andrea Mari, Nathan Shammah, William Zeng, David Clader Zero-noise extrapolation (ZNE) is a quantum error mitigation technique that can be applied in the presence of different noise models, although the usual assumption is that the noise is time-independent. However, time-correlated noise can have a strong influence on quantum circuits and has been widely observed in real physical devices. Schrödinger Wave Auto-Regressive Moving Average (SchWARMA) [1] models allow one to study such time-correlated noise models in quantum circuits, by leveraging the established theory of classical signal processing. We integrate SchWARMA with Mitiq [2] to investigate the performance of zero-noise extrapolation in the presence of temporally correlated noise. We show that the standard ZNE approach breaks down in the presence of time-correlated noise, and we propose how one could overcome these limitations with alternative extrapolation methods. |
Tuesday, March 16, 2021 9:00AM - 9:12AM Live |
E33.00006: Optimized dispersion engineering of coplanar-waveguide-based Josephson traveling-wave parametric amplifiers Corrado P. Mancini, Reinhard Lolowang, Shayne Cairns, Kathy Schonenberg, April Carniol, Gerald W. Gibson, David M. Lokken-Toyli Readout multiplexing of superconducting qubits is a key approach to limit hardware overhead when scaling to larger quantum processors. A requirement of readout multiplexing is that downstream parametric amplifiers have sufficient bandwidth and dynamic range to handle frequency-multiplexed readout signals, thus motivating the adoption of wideband designs such as those achieved with Josephson traveling-wave parametric amplifiers (JTWPAs). Here we describe JTWPAs co-optimized to support the Hummingbird processor made available by IBM Quantum. In particular, we focus on optimizing the JTWPA dispersion engineering using coplanar waveguide resonators. While such resonators offer relaxed fabrication requirements in comparison to lumped element resonators, we discuss how higher frequency modes of coplanar waveguide resonators can lead to unintended couplings between modes that must be managed in the overall frequency allocation of the multiplexed readout. We furthermore explore device designs aimed at mitigating these spurious couplings using additional high-frequency dispersion resonators. |
Tuesday, March 16, 2021 9:12AM - 9:24AM Live |
E33.00007: Cheap readout error mitigation on expensive NISQ devices Ákos Budai, Zoltán Zimborás, András Pályi Readout error mitigation (REM) is an efficient tool to improve the functionality of Noisy Intermediate-Scale Quantum (NISQ) devices. In most superconducting prototype quantum computers, the readout error dominates the errors of individual gates. The level of improvement gained by REM depends on the error probabilities and number of shots available. In this work, we quantify the efficiency of REM for specific quantum protocols, e.g., quantum state tomography. Considering the scenario where the number of available shots is fixed, we find the optimal distribution of these shots between the REM task and the quantum protocol itself. In a second scenario, we find the minimal number of total shots required to perform the quantum protocol with a fixed target precision. These tasks are of direct financial relevance, since certain quantum computer providers bill after the number of shots executed. |
Tuesday, March 16, 2021 9:24AM - 9:36AM Live |
E33.00008: Error mitigation with ideal Clifford gates and noisy ancillas Alessandro Ciani, Matteo Lostaglio Quantum error mitigation techniques are usually conceived in the context of NISQ devices. Here we explore the potential of quasiprobability-based error mitigation in the context of fault-tolerant quantum computing with perfect Clifford gates and noisy magic states. We derive optimal decompositions of the ideal T gate in terms of Cliffords and noisy T gates obtained via state injection of the available magic states. We study how the technique can be used, depending on the noise level, in place or in conjunction with magic state distillation protocols, such as the Bravyi-Haah protocol, to simulate the output of an ideal quantum computation with the desired accuracy. We conclude by highlighting how these techniques provide us with methods to quantify how close a noisy quantum computer is to an ideal one, and how much advantage it provides with respect to a classical computation based on the same method. |
Tuesday, March 16, 2021 9:36AM - 9:48AM Live |
E33.00009: Modeling and suppression of noise in transmons: theory and experiment Vinay Tripathi, Huo Chen, Mostafa Khezri, Ka Wa Yip, Bibek Pokharel, Matthew Kowalsky, Daniel Lidar Currently available superconducting quantum processors with interconnected transmon qubits are noisy. The noise can be attributed to various sources such as open quantum system effects and spurious couplings (crosstalk). The ZZ-coupling between qubits in fixed frequency architectures is always present and contributes to both coherent and incoherent errors. We develop a procedure using dynamical decoupling to separate the errors resulting from crosstalk and demonstrate it through experiments performed on IBM quantum cloud processors. We then model the residual open quantum system effects numerically through circuit Hamiltonians. We use the Redfield master equation with a hybrid bath consisting of both high and low frequency components to fit the experimental free evolution decay for Haar-random initial states. We further reproduce the effects of actual time-dependent dynamical pulses on the IBM processors using the fitting parameters obtained for the free evolution case. |
Tuesday, March 16, 2021 9:48AM - 10:00AM Live |
E33.00010: Generalized Markovian Noise as a Resource for Suppressing Markovian Errors in Superconducting Qubits: Part I (Simulations) Evangelos Vlachos, Haimeng Zhang, Jeffrey Marshall, Tameem Albash, Eli Levenson-Falk Non-Markovian noise environments, i.e. environments with temporal correlation, are well known to have detrimental effects on quantum |
Tuesday, March 16, 2021 10:00AM - 10:12AM Live |
E33.00011: Correlated Charge Noise and Bit Flip Errors in Superconducting Qubits Chris Wilen, Sohair Abdullah, Noah Alexander Kurinsky, Laura Cardani, Giulia D'Imperio, Lara Faoro, Lev B Ioffe, Chuanhong Liu, Alexander M Opremcak, Bradley Christensen, Jonathan L DuBois, Chris Stanford, Claudia Tomei, Robert F McDermott We have characterized fluctuations in offset charge and temporal variations in energy relaxation time in a circuit comprising four weakly charge-sensitive transmon qubits. We find that discrete jumps in offset charge are highly correlated on a length scale over 600 µm; moreover, these jumps are accompanied by a strong transient suppression of qubit energy relaxation time across the millimeter-scale chip. These results are compatible with the direct charging event and associated quasiparticle poisoning due to absorption of gamma rays or cosmic ray muons in the qubit substrate. These results have major implications for proposed schemes to correct quantum errors by monitoring multiqubit parity operators, which assume that errors in the qubit array are uncorrelated. |
Tuesday, March 16, 2021 10:12AM - 10:24AM Live |
E33.00012: A Cryogenic Variable Temperature Microwave Noise Source Slawomir Simbierowicz, Visa Vesterinen, Joshua Milem, Aleksi Lintunen, Mika Oksanen, Leif Roschier, Leif Grönberg, Juha Hassel, David Gunnarsson, Russell Lake We present a cryogenic microwave noise source with a characteristic impedance of 50 Ω designed to be installed in a coaxial line of a cryostat [1]. The bath temperature of the noise source is continuously variable between 0.1 K and 5 K without causing significant heating on the sample space. As a proof-of-concept experiment, we performed Y-factor measurements of an amplifier cascade that includes a traveling wave parametric amplifier and a commercial high electron mobility transistor amplifier. We observed system noise temperatures as low as 680+20-200 mK at 5.7 GHz corresponding to 1.5+0.1 -0.7 excess photons. The device we present has immediate applications in the characterization of solid-state qubit readout lines. |
Tuesday, March 16, 2021 10:24AM - 10:36AM Live |
E33.00013: Fast Dissipation-Induced Entanglement In Circuit-QED Using Parametric Interactions Tristan Brown, Emery Doucet, Florentin Reiter, Raymond W Simmonds, Jose Aumentado, Taewan Noh, Luke Govia, Diego Ristè, Guilhem Ribeill, Leonardo Ranzani, Archana Kamal Dissipative state stabilization seeks to achieve accurate quantum state preparation without the strict timing required by gate-based methods. Recent works have shown how parametric interactions enable the realization of stabilization protocols which do not suffer from the tradeoffs between target state fidelity and preparation time that typically limit the protocols based on resonant driving [1]. In this talk, I will discuss the experimental realization of a parametrically-induced state stabilization scheme in a circuit-QED architecture, where we use novel state-selective parametric driving to prepare a Bell state as an exact dark state of the dissipative dynamics. Our device consists of two transmon qubits coupled to a common resonator with a flux-tunable SQUID coupler. Modulating the loop flux at multiple frequencies allows simultaneous Hamiltonian and dissipation engineering with coupling strengths on the order of tens of MHz. The modular design paves the way towards natural extensions of such schemes to multipartite stabilization. |
Tuesday, March 16, 2021 10:36AM - 10:48AM Live |
E33.00014: Characterizing and Optimizing Qubit Coherence based on SQUID Geometry Leon Ding, Jochen Braumueller, Antti Vepsalainen, Youngkyu Sung, Morten Kjaergaard, Tim Menke, Roni Winik, David K Kim, Bethany Niedzielski, Alexander Melville, Jonilyn Yoder, Cyrus Hirjibehedin, Terry Philip Orlando, Simon Gustavsson, William Oliver Magnetic flux noise is the dominant source of dephasing in tunable superconducting qubits. While the mechanism behind this 1/f flux noise is poorly understood, it has been proposed that it originates from random fluctuations of spin impurities located on the surface of SQUIDs. A previously proposed microscopic model predicts that flux noise increases with the perimeter and decreases with the wire width of the SQUID loop. We discuss a refinement of the previous model for superconducting films of finite thickness which we validate by measuring the flux noise amplitudes of about 50 capacitively shunted flux qubits over a wide range of geometric SQUID parameters. Our results may therefore serve as a guide on how to improve SQUID designs to minimize 1/f flux noise. |
Tuesday, March 16, 2021 10:48AM - 11:00AM On Demand |
E33.00015: Experimental Implementation of Universal Nonadiabatic Geometric Quantum Gates in a Superconducting Circuit ZIYUE HUA, Yuan Xu, Tao Chen, Xiaoxuan Pan, Xuegang Li, Jiaxiu Han, Weizhou Cai, Yuwei Ma, Haiyan Wang, Yipu Song, Zhengyuan Xue, Luyan Sun Using geometric phases to realize noise-resilient quantum computing is an important method to enhance control fidelity. But so far, there is no direct experimental verification of the noise-resilient feature of geometric quantum gates over the dynamical ones. Here, we experimentally realize a universal nonadiabatic geometric quantum gate set in a superconducting qubit chain. We demonstrate a geometric single-qubit rotation gate set with 0.9977(1) average fidelity and a geometric CZ gate with 0.977(9) fidelity. We also experimentally demonstrate the noise-resilient feature of the realized single-qubit geometric gates by comparing their performance with the conventional dynamical gates with different types of errors in the control field. Thus, our experiment proves a way to achieve high-fidelity geometric quantum gates for robust quantum computation. |
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