APS March 2024: QM’s Scientific Lineup
It’s that time of the year again! The APS March Meeting 2024 is on the horizon and will take place in Minneapolis, Minnesota. If you’re a physicist, APS March is likely already marked on your calendar, and for a good reason—it is the largest event for the physics community and THE place to be for discovering and showcasing exciting research breakthroughs.
QM’s team of quantum experts has prepared an insightful lineup of scientific talks you shouldn’t miss. So, if you’re heading to Minnesota for APS March, be sure to add the following talks to your itinerary.
Find us at booth #1317, where the Quantum Machines team will be waiting you. Beyond just showcasing our latest quantum control and cryogenic electronics products, we invite you to get hands-on with the technology pushing the boundaries of quantum computing research and development. Witness firsthand how these tools can take your quantum computing research and experiments to the next level.
Keep reading to dive deeper into the abstracts for our scientific program. We look forward to seeing you soon!
Control Requirements and Benchmarks for Quantum Error Correction
Presenter: Yaniv Kurman
Abstract: Reaching fault-tolerant quantum computation depends on the successful implementation of quantum error correction (QEC). In QEC, quantum gates and measurements are performed to stabilize the computational qubits, while classical computations convert the measurements into estimated logical Pauli frame updates or logical measurement results. While QEC research has concentrated on developing and evaluating QEC codes and decoding algorithms, specification and clarification of the requirements for the classical control system running QEC codes are lacking. Here, we elucidate the roles of the QEC control system, the necessity to implement low latency and parallelizable feed-forward quantum operations, and suggest near-term benchmarks that confront the classical bottlenecks for QEC quantum computation. These benchmarks are based on the latency between a measurement and the operation that depends on it, and incorporate the different control aspects such as quantum-classical parallelization capabilities and decoding throughput. The proposed benchmarks aim to allow the evaluation and development of scalable building blocks of QEC control system toward its realization as a main component in fault-tolerant quantum computing.
Session OD01: 6:00 AM, Sunday, March 3, 2024
The feed-forward latency requirements for Quantum Error Correction
Presenter: Yaniv Kurman
Abstract: One of the greatest challenges in performing fault-tolerant quantum computing in quantum error correction (QEC) is reaching low feed-forward latencies, that is, a short time from the physical execution of a logical measurement until the controller plays a conditional pulse which depends on the logical measurement outcome. The necessity for feed-forward arises from the requirement to perform non-Clifford gates to reach quantum advantage (Gottesman-Knill theorem). To keep track of the logical flips and correct them without propagation, the conditional feed-forward of each non-Clifford gate must depend on the decoding. Here, we provide a general analysis of the feed-forward latency requirements with the latency behavior in different classical setups. Using a dynamical system analysis, we show the conditions on the system latency performance that determine the operation regime: latency divergence, where quantum calculations are unfeasible; classical-controller limited runtime; or quantum-operation limited runtime, where the classical operations do not delay the quantum circuit. The proposed analysis can be used for any decoding algorithm and any QEC stabilizer code towards fault-tolerant quantum computation.
Session OD01: 6:00 AM, Sunday, March 3, 2024
Improving the fidelity of flux-based gates in superconducting processors through model learning of qubit and control stack parameters.
Presenter: Shinibali Bhattacharyya (Qruise GmbH)
The flux-based controlled-phase (CZ) gate promises computational speed-up in the implementation of two-qubit entangling gates. This scheme entails flux control of transmon frequency, maximizing intermediate leakage between computational |1,1> and non-computational |0,2> states by operating at the speed limit of the transverse coupling between these states. The flux-based CZ pulse scheme consists of a single unipolar or bipolar square pulse, applied on the control transmon for a target flux amplitude and specific pulse duration. The corresponding population exchange between the |1,1> and |0,2> states should ideally show symmetric chevron-like oscillation patterns around the target flux amplitude for any given pulse duration. However, experimentally obtained chevrons show broken symmetry in their oscillation patterns at all pulse durations. This affects the fidelity of the flux-based gates due to pulse distortions that are not fully corrected, despite using digital filters on the control line.
Using a physics-informed machine learning framework to minimize the Euclidean distance between the experimental and simulated chevrons, we are able to learn the pulse distortions occurring down the control line, besides learning relevant system Hamiltonian parameters. Our framework complements the Cryoscope technique of measuring the step response of flux control lines, as we also model distortions induced post-digital-to-analog conversion in the control line. The learned parameters are able to simulate the chevrons for the unipolar flux pulses, with a 99.5% match with experimental data. We validate our model learning framework to reproduce the chevrons for the bipolar flux pulses, yielding > 95% match with the corresponding experimental data. We shed light on the physical implication of the learned qubit and control stack parameters on the flux-based CZ protocol. We then lay out actionable insights about correcting the pulse distortions using optimized digital filters that can improve the fidelity of the flux-based gates. Session B50
Session B50: 1:42 PM–1:54 PM, Monday, March 4, 2024, Room: 200H
Chip Packaging with Improved Microwave Performance for Superconducting Quantum Circuits
Presenter: Søren Andresen
Abstract: Chip packaging has become a limiting factor for achieving long-lived coherent operation of superconducting quantum circuits. The local microwave environment represents a source for loss and decoherence that needs to be considered in the packaging design.[1] Quantum Machines and QDevil have developed a chip packaging solution called QCage, optimized for low loss and decoherence, reflection-free transmission, and free from resonances.[2,3] This solution has been adopted by several scientific laboratories that saw vast improvements compared to packaging solutions developed by themselves. In an extensive study of losses in superconducting resonators by the Houck lab at Princeton University, quality factors as high as 200 million were reached in the QCage.24 sample holder.[4] These results indicate that the residual microwave losses in the packaging only contribute to relaxation on time scales of tens of milliseconds, much longer than the best superconducting qubits that have been demonstrated to date.[5] In another study of quasiparticle dynamics in hybrid semiconductor/superconductor Josephson junctions by Shabani lab at New York University, suppression of quasiparticle poisoning was observed.[6] This was partly attributed to the careful EMC shielding of the QCage design.
[1] S. Huang et al., PRX Quantum 2, 020306 (2021)
[2] QCage Product information: https://qdevil.com/qcage-microwave-cavity-sample-holder/
[3] S. Simbierowicz et. al., Rev. Sci. Instrum. 94, 054713 (2023)
[4] K. D. Crowley et al., Phys. Rev. X 13, 041005 (2023)
[5] A. Somoroff et al., Phys. Rev. Lett. 130, 267001 (2023)
[6] B. H. Elfeky et al., PRX Quantum 4, 030339 (2023)
Session T48: 11:30 AM–2:18 PM, Thursday, March 7, 2024, Room: 200E
Hermetic Packaging for Cryogenic Experiments
Authors: Fabio Ansaloni
Abstract: Realizing a universal quantum computer is an extremely complex task. Among the multiple challenges to be solved, extending the coherence times of qubits implemented in solid-state nanodevices is of the utmost importance. Implementing qubits made of electrons trapped at the surface of superfluid helium with vacuum offers the opportunity to realize qubits in a noiseless environment, extending the qubit lifetime [1]. Furthermore, these qubits are compatible with standard circuit quantum electrodynamic (CQED) techniques for manipulation and readout [2].
In this talk, we introduce our newest commercial packaging, used to perform experiments in completely sealed environments at cryogenic temperatures. The technology is based on our recently developed QCage chip carrier [3], which has been optimized for CQED experiments [4,5]. We demonstrate the superfluid helium tightness of this packaging by investigating how the resonance frequency of superconducting coplanar waveguide resonators is evolving as the chip cavity is filled with superfluid helium at cryogenic temperatures.
[1] Platzman, P. M. et al., Science 284, 1967 (1999).
[2] Koolstra, G. et al., Nat Commun 10, 5323 (2019) [3] https://www.quantum-machines.co/products/qcage/
[4] Simbierowicz, S. et al, Rev. Sci. Instrum. 94, 054713 (2023)
[5] Crowley, K. D. et al., Phys. Rev. X, 4, 041005 (2023)
Session T48: 11:30 AM–2:18 PM, Thursday, March 7, 2024, Room: 200E
