Via quantum entanglement, possibly? I honestly have no clue either, but they hint at entanglement, and they don't seem to be worried about observation: "Peng Z

Via quantum entanglement, possibly? I honestly have no clue either, but they hint at entanglement, and they don't seem to be worried about observation: "Peng Zhang, another co-author and member of Zhang's research group, notes that a space-time crystal might also be used to store and transfer quantum information across different rotational states in both space and time."