Resurrection of Schrodinger Cat

Abstract

Quantum decoherence is the major obstacle in using the potential of engineered quantum dynamics to revolutionize high-precision measurements, sensitive detection, or information processing. Here we experimentally demonstrate that quantum state of a system can be recovered after the state is destroyed by uncontrollable natural decoherence. Physical system is a cluster of seven dipolar-coupled nuclear spins of single-labeled 13C-benzene in liquid crystal. 13C spin plays a role of a device for measuring protons' "cat" state, a superposition of states with six spins up (alive) and six spins down (dead). Information about the state, stored in the 13C spin, is used to bring the protons' subsystem into the alive state, while the excess entropy produced by decoherence is transferred to the "measuring device", the 13C spin.