Adaptive quantum state tomography improves accuracy quadratically.
We introduce a simple protocol for adaptive quantum state tomography, which reduces the worst-case infidelity [1-F(ρ,ρ)] 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 ≈ 3 × 10(4)).
Department of Physics, Centre for Quantum Information and Quantum Control and Institute for Optical Sciences, University of Toronto, 60 St. George Street, Toronto, Ontario M5S 1A7, Canada and Canadian Institute for Advanced Research, Toronto, Ontario M5G1Z8, Canada.
D H
DH
Mahler
Lee A
LA
Rozema
Ardavan
A
Darabi
Christopher
C
Ferrie
Robin
R
Blume-Kohout
A M
AM
Steinberg