  Previous studies in quantum information have recognized that specific types
of noise can encode information in certain applications. However, the role of
noise in Quantum Hypothesis Testing (QHT), traditionally assumed to undermine
performance and reduce success probability, has not been thoroughly explored.
Our study bridges this gap by establishing sufficient conditions for noisy
dynamics that can surpass the success probabilities achievable under noiseless
(unitary) dynamics within certain time intervals. We then devise and
experimentally implement a noise-assisted QHT protocol in the setting of
ultralow-field nuclear magnetic resonance spin systems. Our experimental
results demonstrate that the success probability of QHT under the noisy
dynamics can indeed surpass the ceiling set by unitary evolution alone.
Moreover, we have shown that in cases where noise initially hampers the
performance, strategic application of coherent controls on the system can
transform these previously detrimental noises into advantageous factors. This
transformative approach demonstrates the potential to harness and leverage
noise in QHT, which pushes the boundaries of QHT and general quantum
information processing.
