Perfect quantum-state synchronization
We investigate the most general mechanisms that lead to perfect
synchronization of the quantum states of all subsystems of an open quantum
system starting from an arbitrary initial state. We provide a necessary and
sufficient condition for such "quantum-state synchronization", prove tight
lower bounds on the dimension of the environment's Hilbert space in two main
classes of quantum-state synchronizers, and give an analytical solution for
their construction. The functioning of the found quantum-state synchronizer of
two qubits is demonstrated experimentally on an IBM quantum computer and we
show that the remaining asynchronicity is a sensitive measure of the quantum
computer's imperfection.
Jakub Czartowski Ronny Müller Karol Zyczkowski Daniel Braun