Bulletin of the American Physical Society
2024 APS March Meeting
Monday–Friday, March 4–8, 2024; Minneapolis & Virtual
Session M50: Pulse Engineering and Circuit CompilationFocus
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Sponsoring Units: DQI Chair: Qi Ding, Massachusetts Institute of Technology Room: 200H |
Wednesday, March 6, 2024 8:00AM - 8:12AM |
M50.00001: Minimizing spectator errors with optimal control pulse engineering Emma Berger, Daniel Puzzuoli, Holger Haas, Vivek Maurya, Zoé McIntyre, Ken X Wei, David C McKay Spectator errors are a type of coherent, off-resonant error that occur when two qubits with nearby resonant frequencies interact, often due to classical cross-talk or a quantum-mechanical fixed couplings on a device [1]. These errors violate common assumptions about Markovianity usually made in QCVV and QEC protocols and occur at error rates of < 1e-4 on modern devices. While these error rates are relatively low, they will become more essential to address with increasing device complexitity and decreasing overall error rates. To date, there lacks any sort of method to correct off-resonant spectator errors. Here, we use optimal control theory (OCT) to numerically engineer $X_{pi/2}$ pulses that are robust against ZX, XZ, and IX spectator interactions and calibrate the pulse on an IBM test device using the dimensional reduction method developed by our group. We demonstrate a successful implementation of this pulse using the phase-sweep spectroscopy amplification experiment developed in [1] and perform randomized benchmarking to demonstrate that the numerically optimized gate has a comparable or better error rate compared to prototypical DRAG pulses. This result thus showcases the promise for OCT to address non-Markovian spectator errors for which there is no known analytical solution, and highlights the application of OCT designed gates on a real device. |
Wednesday, March 6, 2024 8:12AM - 8:24AM |
M50.00002: Control stacks for quantum advantage Francesco Battistel, Bijan Binaei Haghighi, Daniel Boddou, Mert Büyükmıhcı, Renato da Silva Severo, Damaz de Jong, Fokko de Vries, Edmundo Ferreira, Joel Foreman, Jordy Gloudemans, Antione Gouby, Bilal Kalyoncu, Zuodong Liang, Aviral Mishra, Tahereh Niknejad, Calin Sindile, Marijn J Tiggelman, Willemijntje Uilhoorn, Yigitcan Uzun, Tijmen van Eijk, Wouter Vlothuizen, Daniel J Weigand, Jules van Oven, Cornelis Christiaan Bultink Realizing intermediate-scale quantum computers and fault-tolerant quantum computers requires controlling 1000s of qubits. For this purpose, Qblox has developed a highly distributed control architecture where each module only executes control or readout operations on a small number of qubits. Each module is equipped with a plurality of Q1 processors that in real time sequence pulses, their parameters, and measurement operations. As a result, the stack processes 1000s of outgoing and incoming pulses in full synchronicity while operating with minimal precompilation and communication overhead. We here present a new level of scalability that paves the way for quantum computers with practical applications. |
Wednesday, March 6, 2024 8:24AM - 8:36AM |
M50.00003: Building intermediate-scale quantum control systems in a star network architecture Zhixin Wang, Andrea Corna, Mark Kasperczyk, Chunyan Shi, Bruno Küng, Taekwan Yoon, Edward Kluender, Sebastian Dütsch, Tobias Kammacher, Stefan Altorfer, Nikolaos Anastasiadis, Artem Khvostov, Benjamin Schmid, Liberto Beltrán, Andreas Messner, Flavio Heer, Tobias Thiele The advance of quantum information technology is raising new system engineering challenges in both the quantum and the classical regimes: In the coming years, quantum processors containing 50–500 physical qubits will be more regularly implemented by academic and industrial laboratories for state-of-the-art quantum computation and quantum simulation algorithms. In the meantime, electronics and computer control systems should be capable of supporting experimental progress in a scalable architecture. In this talk, we will present a Quantum Computing Control System (QCCS) solution that can synchronize and feedback-control up to 448 high-fidelity physical channels at microwave frequencies. In this system, modular qubit control units are arranged in a star network to achieve uniform intercommunication latencies and synchronization stabilities. We will emphasize on key features of this system, such as calibration-free microwave frontends, experiment pipelining, and custom FPGA programming of the Quantum System Hub (QHub), and explain its unique advantages in accelerating quantum optimal control and quantum error correction with intermediate-scale quantum information processors. |
Wednesday, March 6, 2024 8:36AM - 8:48AM |
M50.00004: Learning-based Calibration of Flux Crosstalk in Transmon Qubit Arrays Cora N Barrett, Amir H Karamlou, Sarah Muschinske, Ilan T Rosen, Jochen Braumuller, Rabindra Das, David K Kim, Bethany M Niedzielski, Megan Schuldt, Kyle Serniak, Mollie E Schwartz, Jonilyn L Yoder, Terry P Orlando, Simon Gustavsson, Jeffrey A Grover, William D Oliver Superconducting quantum processors comprising flux-tunable data and coupler qubits are a promising platform for analog quantum simulation and digital quantum computation. One challenge to scaling this platform is the magnetic flux crosstalk between flux-control lines and qubits, which impedes precision control of qubit frequencies. To implement high-fidelity quantum operations as processor sizes increase, we need an extensible approach to measure flux crosstalk and compensate for it. We demonstrate the experimental performance of a learning-based approach to DC-flux and fast-flux crosstalk calibration on an array of 16 flux-tunable transmon qubits. The overall calibration time for this approach empirically scales linearly with system size, while achieving a median qubit frequency error below 300 kHz. |
Wednesday, March 6, 2024 8:48AM - 9:00AM |
M50.00005: Enhancing execution efficiency of quantum-classical algorithms through hardware-efficient implementation on FPGAs Abhi D Rajagopala, Neelay Fruitwala, Yilun Xu, Akhil Francis, Gang Huang, Christopher D Spitzer, David I Santiago, Katherine Klymko, Kasra Nowrouzi
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Wednesday, March 6, 2024 9:00AM - 9:12AM |
M50.00006: Fast Full-Device Characterization and Gate Calibration with a Graph-Based Scheduler Ayush M Pancholy, Aaron Barbosa, Varun Menon, Shobhan Kulshreshtha, Yuval Baum, Pranav S Mundada, Marti Vives Reliable calibration of all quantum operations is crucial in obtaining the best device performance limited only by the qubit coherences. Traditionally, calibration is done using slow, resource-intensive model-based experiments executed in a manual or semi-automated operation requiring expert supervision. Due to the inadequacy of the device models for fast gates, the above procedure is often unable to achieve the best device performance. |
Wednesday, March 6, 2024 9:12AM - 9:48AM |
M50.00007: Noise-Aware Circuit Compilations for a Continuously Parameterized Two-Qubit Gateset Invited Speaker: Christopher G Yale Sandia National Laboratories is home to the Quantum Scientific Computing Open User Testbed (QSCOUT), a low-level quantum computing testbed based on a linear chain of trapped 171Yb+ ions. As part of the DOE ASCR Quantum Testbed Program, QSCOUT aims to offer transparency and versatility in exploring quantum algorithms on a noisy-intermediate-scale quantum (NISQ) system and is bolstered by access at a variety of levels within the software stack as deep as pulse-level control. Our all-to-all connected qubit register is hosted by a microfabricated surface-electrode trap, and gates are realized via individually addressed optical Raman transitions. QSCOUT offers continuous parameterization of the two-qubit Mølmer-Sørensen (MS) gate, which has been crucial to a number of recent user collaborations. Here, I will discuss the empirical realization, error sources, and the frequency robustness of our continuously parameterized MS gate, as well as a recent effort to mitigate crosstalk from individual addressing beams. Combining these efforts, we then use Superstaq to develop and study noise-aware compilations focused on the continuously parameterized MS gates. These include swap mirroring to reduce total entangling angle contained in the circuit as well as focusing the heaviest MS angle participation on the best performing gate pairs and/or qubits. From these efforts, we realize distinct improvements in system performance. To conclude, I will present a roadmap of future planned developments to broaden QSCOUT’s offerings, including mid-circuit measurements and multi-qubit entangling gates. |
Wednesday, March 6, 2024 9:48AM - 10:00AM |
M50.00008: Fast Qubit Frequency Tuning Approaches for High-Fidelity CZ Gates in Superconducting Circuits Fabian Marxer, Tuure Orell, Otto Salmenkivi, Jani Tuorila, Jakub Mrozek, Eric Hyyppä, Jyrgen Luus, Alejandro Gómez Frieiro, Alpo Välimaa, Julia Lamprich, Wei Liu, Alessandro Landra, Caspar Ockeloen-Korppi, Jeffrey Chan, Juha Hassel, Kuan Y Tan, Johannes Heinsoo, Antti Vepsäläinen High-fidelity single-qubit and two-qubit gates are foundational components in the realization of practical quantum computing applications. Achieving high gate fidelities in quantum processors based on superconducting circuits face formidable challenges in achieving the requisite gate fidelities, necessitating precise control and calibration procedures. Among these challenges, maintaining flexibility in the qubit idling frequencies to mitigate the effects of parasitic two-level systems and crosstalk during single-qubit gates, while simultaneously ensuring high-fidelity two-qubit gates, stands out as a critical concern. Fast qubit frequency tuning during two-qubit gates offers a practical and readily implementable solution to the aforementioned challenge [1]. Here, we present a comparative analysis of different approaches for tuning qubit frequencies during a controlled-Z gate operation. We systematically evaluate and compare different implementations, highlighting their respective advantages and disadvantages. By investigating different approaches, we provide insights into the trade-offs involved in achieving high-fidelity gates in superconducting quantum processors. |
Wednesday, March 6, 2024 10:00AM - 10:12AM |
M50.00009: Closed-loop Optimization for high-fidelity Controlled-Z Gates in Superconducting Qubits Niklas J Glaser, Max Werninghaus, Federico Roy, João Romeiro, Ivan Tsitsilin, Leon Koch, Niklas Bruckmoser, Johannes Schirk, Malay Singh, Lasse Södergren, Stefan Filipp Qubit operations must be highly accurate and fast to fully exploit the potential of quantum computing. Here, we use a superconducting qubit architecture with fixed-frequency qubits and tunable coupling elements. In this architecture, adiabatic coupler-activated controlled-phase gates, in combination with single-qubit gates, promise high-fidelity qubit operation. However, using simple calibration routines limits the control complexity of the two-qubit gates and may lead to uncontrolled leakage or decoherence effects during the gate. We use a closed-loop optimization based on two-qubit randomized benchmarking sequences with adaptive sensitivity. We calibrate and compare various pulse shapes ranging from minimal parameter sets to piecewise-constant pulse shapes with high complexity. We find that the choice of pulse parametrization can elevate the gate fidelity, decrease the gate time, and reduce leakage by exploiting the full system dynamics and accommodating the transfer functions of the cryogenic cabling. Using these techniques, we obtain controlled-Z gate fidelities of up to 99.9%. |
Wednesday, March 6, 2024 10:12AM - 10:24AM |
M50.00010: Quantum optimal control of superconducting qubits with Q-PRONTO Jieqiu Shao, Marco M Nicotra, Andras Gyenis, Brian Isakov, Mantas Naris Standard methods of Quantum Optimal Control (QOC) have linear convergence in the cost per iteration. In this talk I will describe Q-PRONTO [1,2], a new method for QOC that can achieve quadratic convergence. After briefly describing the method, I will illustrate its use to design gates on two typical superconducting qubits: the transmon and the fluxonium. I will compare Q-PRONTO to other QOC methods and show its advantages in terms of performance. Finally, I will briefly describe the open-source Julia package we have developed to enable anyone to use Q-PRONTO. |
Wednesday, March 6, 2024 10:24AM - 10:36AM |
M50.00011: Co-design of quantum computing devices with optimal control Nicolas Wittler, Frank K Wilhelm-Mauch, Shai Machnes When exploring operating regimes for quantum devices, often specific properties like noise resistance are selected based on previous experience or intuition, resulting in designs like the Transmon, a widely adopted design for superconducting qubit. In the current NISQ era, there is a demand for functional quantum devices to solve relevant computational problems, which motivates a more utilitarian perspective on device design: The goal is to have a device that is employed to run a given algorithm with state-of-the-art performance. |
Wednesday, March 6, 2024 10:36AM - 10:48AM |
M50.00012: Abstract Withdrawn |
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