  We show that every language in QMA admits a classical-verifier,
quantum-prover zero-knowledge argument system which is sound against quantum
polynomial-time provers and zero-knowledge for classical (and quantum)
polynomial-time verifiers. The protocol builds upon two recent results: a
computational zero-knowledge proof system for languages in QMA, with a quantum
verifier, introduced by Broadbent et al. (FOCS 2016), and an argument system
for languages in QMA, with a classical verifier, introduced by Mahadev (FOCS
2018).
