It’s a good question. It’s one of the few features of the C++ version we have not implemented in Julia yet. We may do it, however there are two reasons why it’s less urgent than it might seem:
1. it’s been found that the MPO exponentiation method used for that is not as accurate for time evolution as other methods like Trotter gates or TDVP
2. we should have a TDVP code available in Julia sometime this spring, and TDVP has all of the benefits of MPO time evolution plus many other benefits so it’s basically a superior method
What system are you studying that you need toExpH for? Does it have long-range interactios?