def from_label(cls, label):
"""Return a tensor product of single-qubit operators.
Args:
label (string): single-qubit operator string.
Returns:
Operator: The N-qubit operator.
Raises:
QiskitError: if the label contains invalid characters, or the
length of the label is larger than an explicitly
specified num_qubits.
Additional Information:
The labels correspond to the single-qubit matrices:
'I': [[1, 0], [0, 1]]
'X': [[0, 1], [1, 0]]
'Y': [[0, -1j], [1j, 0]]
'Z': [[1, 0], [0, -1]]
'H': [[1, 1], [1, -1]] / sqrt(2)
'S': [[1, 0], [0 , 1j]]
'T': [[1, 0], [0, (1+1j) / sqrt(2)]]
'0': [[1, 0], [0, 0]]
'1': [[0, 0], [0, 1]]
'+': [[0.5, 0.5], [0.5 , 0.5]]
'-': [[0.5, -0.5], [-0.5 , 0.5]]
'r': [[0.5, -0.5j], [0.5j , 0.5]]
'l': [[0.5, 0.5j], [-0.5j , 0.5]]
"""
# Check label is valid
label_mats = {
'I': IGate().to_matrix(),
'X': XGate().to_matrix(),
'Y': YGate().to_matrix(),
'Z': ZGate().to_matrix(),
'H': HGate().to_matrix(),
'S': SGate().to_matrix(),
'T': TGate().to_matrix(),
'0': np.array([[1, 0], [0, 0]], dtype=complex),
'1': np.array([[0, 0], [0, 1]], dtype=complex),
'+': np.array([[0.5, 0.5], [0.5, 0.5]], dtype=complex),
'-': np.array([[0.5, -0.5], [-0.5, 0.5]], dtype=complex),
'r': np.array([[0.5, -0.5j], [0.5j, 0.5]], dtype=complex),
'l': np.array([[0.5, 0.5j], [-0.5j, 0.5]], dtype=complex),
}
if re.match(r'^[IXYZHST01rl\-+]+$', label) is None:
raise QiskitError('Label contains invalid characters.')
# Initialize an identity matrix and apply each gate
num_qubits = len(label)
op = Operator(np.eye(2**num_qubits, dtype=complex))
for qubit, char in enumerate(reversed(label)):
if char != 'I':
op = op.compose(label_mats[char], qargs=[qubit])
return op
def test_from_label(self):
"""Test from_label method"""
label = 'IXYZHS'
CI = Clifford(IGate())
CX = Clifford(XGate())
CY = Clifford(YGate())
CZ = Clifford(ZGate())
CH = Clifford(HGate())
CS = Clifford(SGate())
target = CI.tensor(CX).tensor(CY).tensor(CZ).tensor(CH).tensor(CS)
self.assertEqual(Clifford.from_label(label), target)
def make_oneq_cliffords():
"""Make as list of 1q Cliffords"""
ixyz_list = [g().to_matrix() for g in (IGate, XGate, YGate, ZGate)]
ih_list = [g().to_matrix() for g in (IGate, HGate)]
irs_list = [IGate().to_matrix(),
SdgGate().to_matrix() @ HGate().to_matrix(),
HGate().to_matrix() @ SGate().to_matrix()]
oneq_cliffords = [Operator(ixyz @ ih @ irs) for ixyz in ixyz_list
for ih in ih_list
for irs in irs_list]
return oneq_cliffords
def to_instruction(self):
"""Convert to Pauli circuit instruction."""
from qiskit.circuit import QuantumCircuit, QuantumRegister
from qiskit.extensions.standard import IGate, XGate, YGate, ZGate
gates = {'I': IGate(), 'X': XGate(), 'Y': YGate(), 'Z': ZGate()}
label = self.to_label()
n_qubits = self.numberofqubits
qreg = QuantumRegister(n_qubits)
circuit = QuantumCircuit(qreg, name='Pauli:{}'.format(label))
for i, pauli in enumerate(reversed(label)):
circuit.append(gates[pauli], [qreg[i]])
return circuit.to_instruction()
def random_clifford_circuit(num_qubits, num_gates, gates='all', seed=None):
"""Generate a pseudo random Clifford circuit."""
if gates == 'all':
if num_qubits == 1:
gates = ['i', 'x', 'y', 'z', 'h', 's', 'sdg', 'v', 'w']
else:
gates = [
'i', 'x', 'y', 'z', 'h', 's', 'sdg', 'v', 'w', 'cx', 'cz',
'swap'
]
instructions = {
'i': (IGate(), 1),
'x': (XGate(), 1),
'y': (YGate(), 1),
'z': (ZGate(), 1),
'h': (HGate(), 1),
's': (SGate(), 1),
'sdg': (SdgGate(), 1),
'v': (VGate(), 1),
'w': (WGate(), 1),
'cx': (CXGate(), 2),
'cz': (CZGate(), 2),
'swap': (SwapGate(), 2)
}
if isinstance(seed, np.random.RandomState):
rng = seed
else:
rng = np.random.RandomState(seed=seed)
samples = rng.choice(gates, num_gates)
circ = QuantumCircuit(num_qubits)
for name in samples:
gate, nqargs = instructions[name]
qargs = rng.choice(range(num_qubits), nqargs, replace=False).tolist()
circ.append(gate, qargs)
return circ