PyTket code for discrete quantum walk

# import time
# from pytket.circuit import Circuit, CircBox, OpType, QControlBox
# from pytket.extensions.qiskit import AerBackend
# from pytket.passes import DecomposeBoxes, SynthesiseTket

# SIZE = 6
# backend = AerBackend()

# # mcx from control on X
# def mcx_gate(num_ctrl_qubits):
#     my_mcx_gate = QControlBox(CircBox(Circuit(1).X(0)), num_ctrl_qubits)
#     return my_mcx_gate

# # get increment circuit as an MCX cascade
# def get_increment_circuit(num_qubits):
#     increment_circuit = Circuit(num_qubits)
#     for j in range(num_qubits - 1):
#         increment_circuit.add_gate(mcx_gate(num_qubits-1-j),[k for k in range(num_qubits-j)])
#     increment_circuit.X(0)

#     return increment_circuit

# # run an example
# start_time = time.time()
# q_walk_step = Circuit(SIZE+1)
# q_walk_step.H(0)
# q_walk_step.add_gate(QControlBox(CircBox(get_increment_circuit(SIZE))),
#     [k for k in range(SIZE+1)])
# q_walk_step.add_gate(QControlBox(CircBox(get_increment_circuit(SIZE)).dagger,n_controls=1,
# control_state=[0]),[k for k in range(SIZE+1)])

# DecomposeBoxes().apply(q_walk_step)
# SynthesiseTket().apply(q_walk_step)
# compiled_circ = backend.get_compiled_circuit(q_walk_step)
# transpilation_time = time.time()-start_time
# depth = compiled_circ.depth()
# cx_counts = compiled_circ.n_gates_of_type(OpType.CX)
# width = compiled_circ.n_qubits

# print(f'==== tket for {SIZE}==== time {transpilation_time}')