I15.5 How to automate this

Codebook
1

def extract_qubit_state(input_state):
“”"Extract the state of the third qubit from the combined state after teleportation.

Args:
    input_state (array[complex]): A 3-qubit state of the form 
        (1/2)(|00> + |01> + |10> + |11>) (a|0> + b|1>)
        obtained from the teleportation protocol.
        
Returns:
    array[complex]: The state vector np.array([a, b]) of the third qubit.
"""

##################
# YOUR CODE HERE #
##################

# DETERMINE THE STATE OF THE THIRD QUBIT
d=list(input_state)
vector=np.array([2*d[2],2*d[1]])
return vector

Here is the teleportation routine for you

dev = qml.device(“default.qubit”, wires=3)

#################

YOUR CODE HERE

##################

OPTIONALLY UPDATE THIS STATE PREPARATION ROUTINE

def state_preparation():
qml.Hadamard(wires=0)
qml.Rot(0.1, 0.2, 0.3, wires=0)

@qml.qnode(dev)
def teleportation():
state_preparation()
entangle_qubits()
rotate_and_controls()
return qml.state()

Print the extracted state after teleportation

full_state = teleportation()
print(extract_qubit_state(full_state))

2

Hi @Vedant_Dwivedi. On the right side of the codebook, on the “4. measurement” section you will find equation 6. Read the equation and the explanation below.

You’re very close to the answer but you’re not using the right elements. of “d”. Look at the equation carefully.

I hope this helps!