Researchers use quantum processors to decode scrambled data

Researchers from National Cheng Kung University, RIKEN, and the University of Michigan have demonstrated a circuit-based protocol to decode quantum information after it has been scrambled, a process where data rapidly spreads across a quantum system. The team used the concept of postselected closed timelike curves, allowing them to interpret a quantum experiment as a consistent time loop for reliable information recovery. This experiment successfully decoded scrambled information seemingly before its original generation, with the success rate linked to out-of-time-ordered correlations, a measure of quantum information scrambling, and implemented on Quantinuum and IBM quantum processors. The core of this approach lies in the use of postselected closed timelike curves (PCTCs), which, unlike traditional time travel concepts, do not require exotic matter or violate causality when combined with postselection. The team’s protocol involves three distinct steps: initial encoding of quantum information using quantum information scrambling, simulation of “time travel” via the PCTC to send encoded information into the past, and…