def _prepare_state(state, qubits):
c = Circuit()
for q, s in zip(qubits, state):
if s == '0':
pass
elif s == '1':
c.append(Gate('X', [q]))
elif s == '+':
c.append(Gate('H', [q]))
elif s == '-':
c.extend([Gate('X', [q]), Gate('H', [q])])
else:
raise ValueError(f"Unexpected token '{s}'")
return c
def expand_iswap(circuit: Circuit) -> Circuit:
"""
Expand ISWAP's by iteratively replacing with SWAP's, CZ's and Phases.
"""
from copy import deepcopy
# Get ideal iSWAP
_iSWAP = Gate('ISWAP').matrix()
# Initialize circuit
_circ = Circuit()
# For each gate in circuit ..
for gate in circuit:
# Check if gate is close to SWAP
if gate.n_qubits == 2 and gate.qubits and np.allclose(
gate.matrix(), _iSWAP):
# Get tags
_tags = gate.tags if gate.provides('tags') else {}
# Expand iSWAP
_ext = [
Gate('SWAP', qubits=gate.qubits, tags=_tags),
Gate('CZ', qubits=gate.qubits, tags=_tags),
Gate('P', qubits=[gate.qubits[0]], tags=_tags),
Gate('P', qubits=[gate.qubits[1]], tags=_tags),
]
# Append to circuit
_circ.extend(_ext if gate.power == 1 else (
g**-1 for g in reversed(_ext)))
# Otherwise, just append
else:
_circ.append(deepcopy(gate))
# Return circuit
return _circ