def __init__(
self,
pauli_string: ps.PauliString,
*,
exponent_neg: Union[int, float, sympy.Expr] = 1,
exponent_pos: Union[int, float, sympy.Expr] = 0,
) -> None:
"""Initializes the operation.
Args:
pauli_string: The PauliString defining the positive and negative
eigenspaces that will be independently phased.
exponent_neg: How much to phase vectors in the negative eigenspace,
in the form of the t in (-1)**t = exp(i pi t).
exponent_pos: How much to phase vectors in the positive eigenspace,
in the form of the t in (-1)**t = exp(i pi t).
Raises:
ValueError: If coefficient is not 1 or -1.
"""
gate = PauliStringPhasorGate(
pauli_string.dense(pauli_string.qubits),
exponent_neg=exponent_neg,
exponent_pos=exponent_pos,
)
super().__init__(gate, pauli_string.qubits)
self._pauli_string = gate.dense_pauli_string.on(*self.qubits)
def __init__(
self,
pauli_string: ps.PauliString,
qubits: Optional[Sequence['cirq.Qid']] = None,
*,
exponent_neg: Union[int, float, sympy.Expr] = 1,
exponent_pos: Union[int, float, sympy.Expr] = 0,
) -> None:
"""Initializes the operation.
Args:
pauli_string: The PauliString defining the positive and negative
eigenspaces that will be independently phased.
qubits: The qubits upon which the PauliStringPhasor acts. This
must be a superset of the qubits of `pauli_string`.
If None, it will use the qubits from `pauli_string`
The `pauli_string` contains only the non-identity component
of the phasor, while the qubits supplied here and not in
`pauli_string` are acted upon by identity. The order of
these qubits must match the order in `pauli_string`.
exponent_neg: How much to phase vectors in the negative eigenspace,
in the form of the t in (-1)**t = exp(i pi t).
exponent_pos: How much to phase vectors in the positive eigenspace,
in the form of the t in (-1)**t = exp(i pi t).
Raises:
ValueError: If coefficient is not 1 or -1 or the qubits of
`pauli_string` are not a subset of `qubits`.
"""
if qubits is not None:
it = iter(qubits)
if any(not any(q0 == q1 for q1 in it)
for q0 in pauli_string.qubits):
raise ValueError(
f"PauliStringPhasor's pauli string qubits ({pauli_string.qubits}) "
f"are not an ordered subset of the explicit qubits ({qubits})."
)
else:
qubits = pauli_string.qubits
# Use qubits below instead of `qubits or pauli_string.qubits`
gate = PauliStringPhasorGate(pauli_string.dense(qubits),
exponent_neg=exponent_neg,
exponent_pos=exponent_pos)
super().__init__(gate, qubits)
self._pauli_string = gate.dense_pauli_string.on(*self.qubits)