qat.linalg.oracles.PhaseOracle

class qat.linalg.oracles.PhaseOracle(targets, arity, msb_first=True)

Phase oracles simply flips the phase of some computational basis state.

I.e:

\(| i \rangle \mapsto (-1)^{f(i)} | i \rangle\)

where \(f:\{0,1\}^n \rightarrow \{0, 1\}\).

For simplicity \(f\) is specified via the list of states \(i\) such that \(f(i) = 1\).

E.g an oracle flipping the phase of states \(| 100 \rangle\) and \(| 001 \rangle\) , would be constructed using:

PhaseOracle([4, 1])

If not arity is specified, the oracle will have a variable arity and will consider the list of targets as a list of states over the full data register

E.g PhaseOracle([4, 1]) applied on a register of length 4 will flip phases of states: \(|0100\rangle\) and \(|0001\rangle\).

Warning

The emulation of this gate is only supported using the LinAlg simulator at this time.

Parameters

  • targets (list<int>) – a list of target states to flip

  • arity (int) – the arity of the oracle (i.e the size of the data register).

  • msb_first (bool, optional) – If set to True, the targets will be flipped using the most-significant-bit first ordering convention. If set to False, assumes least-significant-bit first ordering. Defaults to True.