Witnessing quantum coherence with prior knowledge of observables

Quantum coherence is the key resource in quantum technologies, including faster computing, secure communication, and advanced sensing. Its quantification and detection are, therefore, paramount within the context of quantum information processing. Having certain prior knowledge of the observables may enhance the efficiency of coherence detection. In this work, we posit that the trace of the observables is a known quantity. Our investigation confirms that this assumption indeed extends the scope of coherence-detection capabilities. Utilizing this prior knowledge of the trace of the observables, we establish a series of coherence-detection criteria. We investigate the detection capabilities of these coherence criteria from diverse perspectives and ultimately ascertain the existence of four distinct and inequivalent criteria. These findings contribute to the deepening of our understanding of coherence-detection methodologies, thereby potentially opening new avenues for advancements in quantum technologies.