Effects of coherence on temporal resolution

Measuring small separations between two optical sources, either in space or time, constitutes an important metrological challenge as standard intensity-only measurements fail for vanishing separations. Contrarily, it has been established that appropriate coherent mode projections can appraise arbitrarily with quantum-limited precision. However, the question of whether coherence brings any advantage to is still a point debate. Here, we elucidate this problem by experimentally investigating effect varying on estimating temporal separation single-photon pulses. We show that, accurate interpretation, special attention must be paid properly normalize quantum Fisher information account strength signal.