🤖 AI Summary
This work addresses the lack of anytime-valid uncertainty quantification in quantum state tomography under continuous measurements by introducing, for the first time, the theory of anytime-valid confidence sequences to this domain. The proposed method constructs dynamic confidence sets with user-specified coverage probabilities that are statistically valid at every measurement time, thereby providing rigorous, real-time uncertainty guarantees throughout the entire process of incremental quantum state estimation. Numerical experiments confirm that the method strictly adheres to the prescribed theoretical coverage at all time points, enabling both real-time and statistically sound quantum state reconstruction.
📝 Abstract
In this letter, we address the problem of developing quantum state tomography (QST) methods that remain valid at any time during a sequence of measurements. Specifically, the aim is to provide a rigorous quantification of the uncertainty associated with the current state estimate as data are acquired incrementally. To this end, the proposed framework augments existing QST techniques by associating current point estimates of the state with confidence sets that are guaranteed to contain the true quantum state with a user-defined probability. The methodology is grounded in recent statistical advances in anytime-valid confidence sequences. Numerical results confirm the theoretical coverage properties of the proposed anytime-valid QST.