Coherence as maximal imaginarity generated by incoherent operations

Since both coherence and imaginarity have proven to be fundamental resources in quantum information processing and their definitions are both relative to a given basis, it is natural to investigate the conversion between them. In this work, we prove that a quantum state can be transformed into a state with nonvanishing imaginarity resource by incoherent operations if and only if it has nonvanishing coherence resource. On the other hand, we demonstrate that a quantum state can be transformed into a state with vanishing coherence resource by orthogonal operations if and only if it has vanishing imaginarity resource. Based on these results, we show that for any imaginarity measure, a corresponding coherence measure can be defined as the maximal amount of imaginarity generated by incoherent operations, and that for any coherence quantifier, a corresponding imaginarity quantifier can be defined as the minimal coherence generated by orthogonal operations.