Adaptive Quantum State Tomography Improves Accuracy Quadratically
Dylan H. Mahler, Lee A. Rozema, Ardavan Darabi, Christopher Ferrie, Robin Blume-Kohout, Aephraim M. Steinberg · Physical Review Letters · 2013
We introduce a simple protocol for adaptive quantum state tomography, which reduces the worst-case infidelity [$1\ensuremath{-}F(\stackrel{^}{\ensuremath{\rho}},\ensuremath{\rho})$] between the estimate and the true state from $O(1/\sqrt{N})$ to $O(1/N)$. It uses a single adaptation step and just one extra measurement setting. In a linear optical qubit experiment, we demonstrate a full order of magnitude reduction in infidelity (from 0.1% to 0.01%) for a modest number of samples ($N\ensuremath{\approx}3\ifmmode\times\else\texttimes\fi{}{10}^{4}$).