def apply_twoqubit_gate(self, gateU, qubit1, qubit2):
"""
Applies a unitary gate to the two specified qubits.
Arguments:
gateU unitary to apply as Qobj
qubit1 the first qubit
qubit2 the second qubit
"""
# Construct the overall unitary
overallU = qp.gate_expand_2toN(gateU, self.activeQubits, qubit1,
qubit2)
# Qutip distinguishes between system dimensionality and matrix dimensionality
# so we need to make sure it knows we are talking about multiple qubits
k = int(math.log2(overallU.shape[0]))
dimL = []
for j in range(k):
dimL.append(2)
overallU.dims = [dimL, dimL]
self.qubitReg.dims = [dimL, dimL]
# Apply the unitary
self.qubitReg = overallU * self.qubitReg * overallU.dag()
def apply_double_gate(self, gate, control_name, target_name):
if not isinstance(gate, qutip.Qobj):
raise TypeError("Gate has to be of type Qobject.")
self._lock()
control = self._qubit_names.index(control_name)
target = self._qubit_names.index(target_name)
gate = qutip.gate_expand_2toN(gate, self.N, control, target)
self.data = gate * self.data * gate.dag()
self._unlock()
def _expand_gate(op: qutip.Qobj, from_qubits: int, to_qubits: int, targets: List[int]):
assert len(targets) == from_qubits
if from_qubits == 1:
return qutip.gate_expand_1toN(op, to_qubits, targets[0])
elif from_qubits == 2:
return qutip.gate_expand_2toN(op, to_qubits, targets=targets)
else:
raise ValueError('Unsupported from_qubits value')
def as_large_qobj_operator(self, num_qubits: int) -> qutip.Qobj:
if self.typ.num_qubits == 2:
return qutip.gate_expand_2toN(self.as_qobj_operator(),
num_qubits,
targets=self.qubits)
elif self.typ.num_qubits == 1:
return qutip.gate_expand_1toN(self.as_qobj_operator(), num_qubits,
self.qubits[0])
else:
raise NotImplemented('Not implemented for large gates')
def crz(theta, N=None, control=0, target=1):
if (control == 1 and target == 0) and N is None:
N = 2
if N is not None:
return gate_expand_2toN(crz(theta), N, control, target)
else:
return Qobj([[1, 0, 0, 0],
[0, 1, 0, 0],
[0, 0, np.exp(1j * theta / 2), 0],
[0, 0, 0, np.exp(-1j * theta / 2)]],
dims=[[2, 2], [2, 2]])
def cy(N=None, control=0, target=1):
if (control == 1 and target == 0) and N is None:
N = 2
if N is not None:
return gate_expand_2toN(cy(), N, control, target)
else:
return Qobj([[1, 0, 0, 0],
[0, 1, 0, 0],
[0, 0, 0, -1.j],
[0, 0, 1.j, 0]],
dims=[[2, 2], [2, 2]])
def cu3(theta3, N=None, control=0, target=1):
if (control == 1 and target == 0) and N is None:
N = 2
if N is not None:
return gate_expand_2toN(cu3(theta3), N, control, target)
else:
return Qobj([[1, 0, 0, 0],
[0, 1, 0, 0],
[0, 0, np.cos(theta3[0] * 0.5) * np.exp(1j * theta3[1] * 0.5) * np.exp(1j * theta3[2] * 0.5),
-np.sin(theta3[0] * 0.5) * np.exp(1j * theta3[1] * 0.5) * np.exp(-1j * theta3[2] * 0.5)],
[0, 0, np.sin(theta3[0] * 0.5) * np.exp(-1j * theta3[1] * 0.5) * np.exp(1j * theta3[2] * 0.5),
np.cos(theta3[0] * 0.5) * np.exp(-1j * theta3[1] * 0.5) * np.exp(-1j * theta3[2] * 0.5)]],
dims=[[2, 2], [2, 2]])
