Coherence-based characterization of macroscopic quantumness

One of the most elusive problems in quantum mechanics is transition between classical and physics. This problem can be traced back to Schr\"odinger's cat thought experiment. A key element that lies at center this lack a clear understanding characterization macroscopic states. Our quantumness relies on states such as Greenberger-Horne-Zeilinger (GHZ) or NOON state. Here we take first-principle approach problem. We start from coherence quantity captures notion require collective macroscopic. To end, introduce which macroscopically distinct construct measure quantifies how global state is. work also provides way derive well-established like GHZ maximize our measure. paves towards better quantum-to-classical transition.