The main goal any researcher bears in mind when investigating Quantum Processing Units (QPUs) in his or her lab, is to extract the parameters of interest in a fast, reliable, and customizable fashion. The harsh reality, however, requires compromising at least one of the three.
As the landscape of hardware control electronics and even the responsibilities of different layers in a quantum computing stack are still changing, lab operators understandably seek abstraction and hardware-agnosticism for their software tools. As Prof. Gary Steele, Antoni van Leeuwenhoek Professor at the Kavli Institute of Nanoscience in Delft put it:
“My dream would be that we would have an API that would let us use experimental protocols interchangeably on different underlying hardware with the same or minimal modified scripts.”
The good news is, we are working on it! Surely this does not take away the need for a compatible and full-stack hardware control electronics setup, but it can improve cross-platform usability.
As part of our role as an OEM of quantum chip test equipment, we develop dedicated software libraries for characterization experiments and reflecting on this year, the following sections will give a brief overlook on our progress on that front.
Quantum Diagnostics Libraries (QDL)
The idea for QDL is to provide a higher-level programming interface for the user with physics-based APIs in mind. To avoid issues related to proprietary hardware-control frameworks, we built our QDL on top of the open-source framework Quantify. This enables QDL to be used with room-temperature control electronics of different vendors. Quantify also serves as holistic hardware abstraction layer to conduct any quantum-computing and solid-state physics experiment.
The standardization of the API allows reusability of custom defined protocols and accelerates the data-acquisition cycle without compromising customizability. QDL on top of Quantify allows us to go beyond the loose scripts usually provided by the standard firmware of room-temperature electronics. The long-term vision for QDL is to holistically provide the software tools, from experiment protocols to automation frameworks, to enable fast, reliable, and customizable diagnostics on different control hardware and different qubit platforms. It is however not the only prerequisite for fast characterization. If you want to learn more about the hardware side of the control stack, have a look at our Orange Rack. If you need a full-stack test setup working fast and reliably, consider our Orange R&D System.
For more information on Superconducting Qubit Tools (SCQT), Travelling Wave Parametric Amplifier Tools (TWPA Tools) and GRaph-based Automated Calibration Execution (GRACE), go to the Quantum Diagnostics Libraries product page.
Superconducting Qubit Tools (SCQT)
A promising architecture for quantum computing is provided by superconducting qubit types, such as the flux-tunable transmon. Due to the large degree of engineering freedom, fast development cycles are needed to explore the vast solution space of possible configurations. Unfortunately, this process is slowed down by the difficulty of accessing the performance indicators of the quantum device, due to too long tune-ups, and manual processes. SCQT as part of QDL tackles this by providing a suite of ready-to-use protocols for spectroscopy and time-domain experiments. Next to the ability to create custom protocols, the library contains pre-defined analysis and calibration tools for key parameters; from qubit frequencies, over coherence times, two-qubit gate fidelities to crosstalk and many more. Although already extensive we constantly work on new features, such as TLS spectroscopy or two-qubit tune-ups with tunable couplers, which are scheduled for 2024. Positively received is our well-sorted documentation which includes actionable tutorials and recipe-like How-To’s, as well as a smooth binary installation.
Travelling Wave Parametric Amplifier Tools (TWPA Tools)
The TWPA Tools libraries are a recently developed part of QDL, which allows for the characterization of TWPA devices using a compatible Vector Network Analyzer (VNA). Harnessing the fast parameter sweeps of the VNA and automation modules, users can diagnose all quantities of interest from transmission or reflection signals, over noise spectrum, to gain compression and ripple. The next version will furthermore allow Quantum Efficiency measurements when used in combination with SCQT.
GRaph-based Automated Calibration Execution (GRACE)
GRACE is a framework for automated calibrations based on a directed acyclic graph to execute (custom) protocol sequences, and its structure underlies all QDL libraries. As stated above, the manual control and required expertise to operate test set-ups is one obstacle we aim to remove. Hence, GRACE allows users to use pre-defined as well as custom protocol chains to automate their workflows around SCQT and TWPA Tools. The interdependency of protocols relying on the correct execution of previous protocols makes this difficult, especially when dealing with the error-prone qubits of today. GRACE is aware of this and allows to visualize and monitor the protocol chains in an auto-built dependency graph. Together with the built-in robustness on the protocol level, it allows the automated calibration of multi-qubit devices. With no prior knowledge of QPU parameters, GRACE achieved diagnostics from feedline spectroscopy up to coherence times measurements in about 8 minutes on a device with 5 flux-tunable transmon qubits. Support for parallel experiments will reduce this time further in 2024.
Read more about GRACE in this news item or watch it at work on YouTube: