Impossibility of succinct quantum proofs for collision-freeness

  • Authors:
  • Scott Aaronson

  • Affiliations:
  • MIT

  • Venue:
  • Quantum Information & Computation
  • Year:
  • 2012

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Abstract

We show that any quantum algorithm to decide whether a function f : [n] → [n] is a permutation or far from a permutation must make Ω (n1/3/w) queries to f, even if the algorithm is given a w-qubit quantum witness in support of f being a permutation. This implies that there exists an oracle A such that SZKA ⊄ QMAA, answering an eight-year-old open question of the author. Indeed, we show that relative to some oracle, SZK is not in the counting class A0PP defined by Vyalyi. The proof is a fairly simple extension of the quantum lower bound for the collision problem.