Curator's Take
This article introduces AQUIRE, a significant advancement in quantum measurement protocols that tackles two critical challenges in quantum computing: working with qudit systems (quantum digits with more than two states) and accounting for real-world noise. While most quantum protocols focus on qubits, qudits offer richer computational possibilities, and AQUIRE provides the first method to accurately estimate quantum observables on these systems while continuously adapting to hardware imperfections. The protocol's Bayesian approach allows it to dynamically adjust measurements in real-time based on accumulated data and observed errors, potentially making quantum computations more reliable and efficient. This work represents an important step toward practical quantum computing on diverse hardware platforms, especially as the field explores alternatives to traditional qubit-based systems.
— Mark Eatherly
Summary
The accurate estimation of observables is a crucial task in quantum computing. Recent advances have highlighted the need for (a) specialized protocols for qudit-based devices, that include (b) error-aware strategies. Here, we present AQUIRE, the first protocol that can (a) accurately estimate both the mean and the error of an observable on qudit-based quantum computers. AQUIRE achieves this by constructing a Bayesian model to accommodate generalized Pauli operators. It is designed to continuously monitor the estimated average and the associated error of the observable, adjusting the subsequent measurements in real-time. Additionally, AQUIRE is (b) device- and experiment-specific error-aware, and accounts for hardware imperfections and experimental noise during the estimation process. We demonstrate AQUIRE's advantage via numerical simulations and showcase its ability to quantify the noise affecting the estimation by implementing it on a trapped-ion qudit quantum processor. By exploiting general commutation relations and overlap grouping measurements, our protocol is state-of-the-art when restricted to qubit-based quantum computers and extends this advantage to the qudit case.