Quantum controls can stretch, blur and even reverse the arrow of time
Luis Pedro García-Pintos, Alexey Gorshkov and Yi-Kai Liu, of NIST and the University of Maryland, developed quantum control protocols that reshape entropy production, generating dynamics that appear more compatible with time flowing backward than forward.
Using measurement and feedback, the schemes can suppress, blur or invert the apparent arrow of time, engineering effectively time-reversed trajectories in open quantum systems. The work connects directly to time-reversal symmetry and the statistical origin of irreversibility, showing that the arrow is a controllable, resource-dependent feature rather than an absolute.
The results bear on quantum thermodynamics, the cost of erasing or reversing information, and fluctuation-theorem accounts of entropy production.