Temporal Quantum Correlations in Superconducting-Qubit Systems

Nonlocality has long been studied through quantum correlations between spatially separated measurements on the bipartite systems. Its temporal analogue, in which measurements on a quantum state are separated in time, examines the quantum correlations violating the macrorealism, for example the Leggett-Garg inequality. In this work, we investigate the temporal quantum correlations of a superconducting qubit undergoing stochastic noise through the studies of the nonmacrorealism, temporal steering, and temporal inseparability. Decoherence of different forms can be observed with the quantum correlations, and unique sudden-death and revival of temporal correlations under non-Markovianity can also be identified and quantified. Our work shows that the temporal quantum correlations can provide a benchmark for the decoherence in superconducting quantum devices.