Perfect quantum state transfer with randomly coupled quantum chains

We suggest a scheme that allows arbitrarily perfect state transfer even in the presence of random fluctuations in the couplings of a quantum chain. The scheme performs well for both spatially correlated and uncorrelated fluctuations if they are relatively weak (say 5%). Furthermore, we show that given a quite arbitrary pair of quantum chains, one can check whether it is capable of perfect transfer by only local operations at the ends of the chains, and the system in the middle being a ‘black box’. We argue that unless some specific symmetries are present in the system, it will be capable of perfect transfer when used with dualrail encoding. Therefore our scheme puts minimal demand not only on the control of the chains when using them, but also on the design when building them.