Efficient Measurement of Quantum Dynamics via Compressive Sensing

TLDR

Quantum system dynamics characterization requires resources that grow exponentially with system size. The study adapts compressive sensing to drastically reduce the experimental configurations needed for quantum process tomography. The method applies to nearly‑sparse dynamical processes, uses only single‑body preparations and measurements, and was tested by estimating process matrices for a photonic two‑qubit logic gate under varying decoherence strengths. The technique achieved accurate, noise‑robust estimation of process matrices for the photonic two‑qubit logic gate, demonstrating its effectiveness for scaling quantum technologies.

Abstract

The resources required to characterise the dynamics of engineered quantum systems-such as quantum computers and quantum sensors-grow exponentially with system size. Here we adapt techniques from compressive sensing to exponentially reduce the experimental configurations required for quantum process tomography. Our method is applicable to dynamical processes that are known to be nearly-sparse in a certain basis and it can be implemented using only single-body preparations and measurements. We perform efficient, high-fidelity estimation of process matrices on an experiment attempting to implement a photonic two-qubit logic-gate. The data base is obtained under various decoherence strengths. We find that our technique is both accurate and noise robust, thus removing a key roadblock to the development and scaling of quantum technologies.