Class Description

QMA⁺(2): QMA(2) With Non-Negative Amplitudes

Same as QMA(2), except now *each* witness must contain a state with non-negative amplitudes in the computational basis.

This class was defined in [JW23] as a possible approach to prove QMA(2) equals NEXP. QMA⁺(2) at some completeness-soundness gap is equal to QMA(2), but at another constant gap, it is equal to NEXP. As of 2025 this problem is still open.

See also QMA⁺.

Linked From

No class.