A quantum oracle separation between QMA(2) and QMA

We find a quantum oracle relative to which QMA  = QMA(2). As a consequence, we resolve the nodisentanglers conjecture of Watrous: for every ε + δ < 1, any (ε, δ)-disentangler requires input size exponential in the number of output qubits. Our proof combines the unitarily invariant polynomial method of She and Yuen (ITCS ’23) with a new construction based on the symmetric and antisymmetric subspace projectors, reducing the QMA lower bound to the approximate degree of OR.