Quantifying the phase of quantum states

• DOI: 10.1016/j.physleta.2023.129049
• Publication Date: 2023-07-31T15:26:24Z
• Authors: Jianwei Xu
• Keywords: Quantum Physics; FOS: Physical sciences; Quantum Physics (quant-ph)

Phase is a basic ingredient for quantum states since quantum mechanics uses complex numbers to describe quantum states. In this letter, we introduce a rigorous framework to quantify the phase of quantum states. To do so, we regard phase as a quantum resource, and specify the free states and free operations. We determine the conditions a phase measure should satisfy and provide some phase measures. We also propose the notion of intrinsic phase for quantum states.<br/>8 pages, 3 figures. Any comments are welcome!<br/>