Qruise GmbH

The Qruise software will be adapted, extended and applied to accelerate the development of MUNIQC-Atoms: extend the capabilities of the "digital twin" simulator to describe Rydberg atoms, initialization errors, noise processes, and readout inaccuracies unique to this platform, and modify the system characterization and optimal control modules accordingly. Qruise will also contribute to developing the control software for fast optical modulators. Combined with a calibration module adapted to the Rydberg readout characteristics, MUNIQC-Atoms will be able to achieve the targeted gate fidelity. Qruise will make its digital twin available to quantum error correction developers and link the QISKIT software stack to the MUNIQC-Atoms quantum computer.

What are the goals?

• Enhance existing Qruise software to be able to create a digital twin of the Phase 1 demonstration platform by mid-project.
• Improve the calibration algorithms adapted to Rydberg to account for the relatively low repetition rate and thus the comparatively high shot noise of Rydberg platforms.
• Provide MUNIQC-Atoms system designers with the characterization, modeling, and calibration tools necessary to maximize the operability of single-, dual-, and multi-qubit gates, much faster than would otherwise have been possible.
• Adapt and enhance the existing Qruise software so that it is capable of producing a digital twin of the much larger Phase 2 demonstrator platform by the end of the project.

How do we plan to achieve that?

Qruise will extend the existing techniques for modeling quantum systems and adapt them to the specific needs for realistic simulation of the Rydberg atoms in the demonstrator. For this purpose, the possible initialization errors will be analyzed and incorporated into the physical model, noise processes will be matched with the experimental setup and, if necessary, new mathematical descriptions will be designed and strategies for reproducing the error-prone readout accuracy will be implemented. In order to be able to perform final optimization steps directly on the device and to freshly adjust much-used operations after small changes (unavoidable over time in such a highly sensitive setup), a customized calibration algorithm for the Rydberg grid will be designed. For this purpose, parameters for variation are identified and optimally adjusted by the software, taking into account the device-specific limits and limitations. To make this possible, suitable measurement schemes must first be implemented that reflect the quality of these operations and the influence of changes to parameters on them. In this context, we will suitably parameterize and specifically modulate all available control fields (laser, photonic circuits).

In order to perform the calibrations directly on the instrument, Qruise optimization software will interact efficiently with the specific APIs of the experiment's control electronics. Since the latter change from experiment to experiment (e.g., Zurich Instrument vs. Keysight vs. home-built waveform generators), Qruise will create new software, typically referred to as "instrument drivers," that interface Qruise's generic internal APIs with those of the demonstrator. Doing this efficiently while enabling high utilization of the quantum devices (i.e., utilizing the quantum processors as much as possible and avoiding artificial dead times). This is non-trivial, with the details depending heavily on the implementation details of the experimental electronics API. Calibration of the model requires constant recalibration and accurate characterization of the system. Qruise will adapt these modules to the Rydberg setup and develop and provide new characterization strategies. The Optimal Control module will be extended to take optimal advantage of the mechanisms and requirements of strontium-based gates. In addition, the peripherals for manipulating the qubits will be considered and the characteristics and influences of the trap potentials for fixing them will be incorporated.

The extension of the setup to a higher number of qubits requires a much more complex simulation and therefore an adaptation of the digital twin. The digital twin will be adapted to allow parallel simulation of its subsystems. It should be noted here that a complete and detailed simulation of the entire model is of course impossible, because if this were possible, we would not need a quantum computer. Therefore, the challenge here is to overcome this crucial hurdle of scaling via division into subsystems and parallelized calibration and characterization.