Fig. 3: Experimental demonstration of enhanced quantum hypothesis testing.

The success probability for discriminating two magnetic fields with different directions versus the encoding time t. The magnetic field strength are B₀ = B₁ = 1.86 nT, with θ₀ = 75^∘ and θ₁ = 30^∘. The black dashed line denotes the maximum success probability that can be achieved under the unitary dynamics. The brown dashed line represents T₂ = 2T₁. The solid lines are theoretical simulations, while triangles, squares, and diamonds are experimental data under different noisy strengths. The error bars are obtained from eight repeated experiments. In the subfigure, the maximal enhancement η is plotted as a function of \({\log }_{10}({T}_{1}/{T}_{2})\).