  We construct a constant-round zero-knowledge classical argument for NP secure
against quantum attacks. We assume the existence of Quantum Fully-Homomorphic
Encryption and other standard primitives, known based on the Learning with
Errors Assumption for quantum algorithms. As a corollary, we also obtain a
constant-round zero-knowledge quantum argument for QMA.
  At the heart of our protocol is a new no-cloning non-black-box simulation
technique.
