Jensen-Shannon divergence coherence and its quantum speed limit

The rate at which quantum coherence is generated or degraded significantly impacts quantum information processing. The minimum time for the coherence-changing process can be well evaluated using the quantum speed limit (QSL), which typically requires taking the maximum across different QSL bounds. In this paper, we derive a coherence QSL bound using the quantum Jensen-Shannon divergence as a coherence measure. It is shown that for any state, there is always a representation in which the dephasing dynamics can saturate the QSL bound. We also numerically demonstrate that our QSL bound can be tighter than previous bounds for some applications. Our results make up for the tightness of the coherence QSL.