Node number

Codercise I.14.2

Expected behavior

IMPLEMENT THE MULTIPLEXER

IF STATE OF FIRST TWO QUBITS IS 01, APPLY X TO THIRD QUBIT

qml.MultiControlledX(control_wires=[0,1], wires=2, control_values='01') The above code should result in the desired behaviour, that is, give the correct output.

Actual behavior

Incorrect: your circuit does not have the correct action on |01>.

Is however, the error being raised!

Additional information

No response

Source code

No response

Tracebacks

No response

• [X] I have searched existing GitHub issues to make sure the issue does not already exist.

Node number

Node I

Expected behavior

When finishing lessons in Node A before Node I, Node A should still be marked as complete.

Actual behavior

Node A will get back to an incomplete state (white circle) when it was finishing before Node I.

Additional information

I finished Node A before Node I. Node I is marked as complete (green circle). However, Node A (which previously finished) is not anymore.

I am not certain about other node (like if you do the lesson backward, etc.). You might have to check them as well.

Source code

No response

Tracebacks

No response

• [X] I have searched existing GitHub issues to make sure the issue does not already exist.

Node number

T

Expected behavior

I scroll to the bottom, and then the accept terms button becomes active

Actual behavior

Accept terms never becomes active

Additional information

Tried with and without Ublock Origin enabled (Chrome/Windows)

Source code

No response

Tracebacks

No response

• [X] I have searched existing GitHub issues to make sure the issue does not already exist.

Feature details

In Codercise I.7.3, the solution accepted as correct seems to be the wrong one.

In the explanation following the question, 2 solutions are presented as being the only possible ones, and the second one (HTTHTH) is indicated as the correct one. However, the submission for the previous question only accepts the first one (HTHTTH) as the right answer.

I worked out the math, and can confirm that the second one (HTTHTH) is the right answer as indicated in the text but not in the accepted solution to the codercise.

Additional information

No response

Feature details

As explained here, the grader is marking a wrong answer (Hadamard on wire 1) as correct while marking wrong the correct answer (Hadamard on wire 0).

Additional information

No response

Feature details

Hi there,

There is a small error in the left panel equation display of the action of $RY(\theta)$ on the computational basis states in I.6 (in the discussion after codercise I.6.3). The sign of the $\sin(\theta/2)$ terms is reversed.

Note that the expressions for this are correct in the corresponding place in the right "textbook" panel (end of the solution to exercise I.6.3).

Additional information

No response

Feature details

Solution to Exercise I.10.2.c is given as 3.022769, but using Wolfram Alpha to calculate the provided matrix multiplication suggests that the answer should be -0.302769 instead.

Using Pennylane to measure

dev = qml.device("default.qubit", wires=1)
    @qml.qnode(dev)
    def qf():
        qml.MottonenStatePreparation([4 / 5, -3 / 5 * np.e ** (1j * np.pi / 3)], 0)
        return qml.expval(qml.Hermitian(np.array([[1, -2 * 1j], [2 * 1j, 2]]), 0))
print(qf())

also yields -0.3027687752661218

Additional information

No response

Node number

I.7.3

Expected behavior

Not to accept my answer

Actual behavior

My answer HTHT was accepted.

Additional information

No response

Source code

dev = qml.device("default.qubit", wires=1)

@qml.qnode(dev)
def unitary_with_h_and_t():
    
    qml.Hadamard(wires = 0)
    qml.T(wires = 0)
    qml.Hadamard(wires = 0)
    qml.T(wires = 0)
    
    

    return qml.state()

Tracebacks

No response

• [X] I have searched existing GitHub issues to make sure the issue does not already exist.

Node number

Node G.4, Exercise Exercise G.4.1

Current content

In the solution of Exercise G.4.1, item (a):

The first term in the equation read $\left ( U \left | u\right \rangle \right )^\dagger \left | v\right \rangle$, but there's a $U$ missing, acting on $\left | v\right \rangle$

Expected content

The first term in the equation should be:

$\left ( U \left | u\right \rangle \right )^\dagger U \left | v\right \rangle$

Or even

$\left ( U \left | u\right \rangle \right )^\dagger \left ( U \left | v\right \rangle \right )$

• [X] I have searched existing GitHub issues to make sure the issue does not already exist.

Node number

Codercise I.13.4.

Current content

The question does not contain the actual syntax of the MultiControlledX gate.

Expected content

A tip/hint drop down which contains:

qml.MultiControlledX(control_wires=[control_1, control_2], wires=target_wire, control_values=string_of_control_values)

• [X] I have searched existing GitHub issues to make sure the issue does not already exist.

Node number

Codercise I.5.4

Current content

The depth of the original circuit is 8, and there are 13 combined T and T† gates. The original T-depth is 6.

Expected content

The original T-depth should be 5 since the second qubit has a maximum of 5 T gates in a row.

• [X] I have searched existing GitHub issues to make sure the issue does not already exist.

Node number

Node I.1, codercises I.1.2

Expected behavior

Codercise I.1.2 should throw an error if user mistakenly submits the inner product <state_2 | state_1> instead of <state_1 | state_2>.

Possible solution: Have grader use complex-valued states for which <state_1 | state_2> != <state_1 | state_1>

Actual behavior

Grader passes even if user submits answer for <state_2 | state_1>.

Additional information

For example, the grader passes if user inputs:

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

    # COMPUTE AND RETURN THE INNER PRODUCT

    return  np.vdot(state_2,state_1)

or

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

    # COMPUTE AND RETURN THE INNER PRODUCT

    return  np.dot(state_1,np.conjugate(state_2))

Source code

No response

Tracebacks

No response

Check other issues

• [X] I have searched existing GitHub issues to make sure the issue does not already exist.

Node number

Node I.1, codercises I.1.1

Expected behavior

Codercise I.1.1 should throw an error if user normalizes state without taking the norm of the complex amplitudes.

Possible solution: Have grader use complex-valued variables to check answers.

Actual behavior

Grader passes even if normalization constant is not calculated correctly (a^2 + b^2 = 1 instead of |a'|^2 + |b'|^2 = 1`).

Additional information

For example, the grader passes if user inputs:

    # CREATE A VECTOR [a', b'] BASED ON alpha AND beta SUCH THAT |a'|^2 + |b'|^2 = 1
    norm_psi = np.array([alpha,beta])/np.sqrt(alpha**2+beta**2)
    # RETURN A VECTOR
    return norm_psi

or

    # CREATE A VECTOR [a', b'] BASED ON alpha AND beta SUCH THAT |a'|^2 + |b'|^2 = 1
    psi = np.array([alpha,beta])
    norm_psi = psi/np.sqrt(np.dot(psi,psi))
    # RETURN A VECTOR
    return norm_psi

The correct implementations should be:

    # CREATE A VECTOR [a', b'] BASED ON alpha AND beta SUCH THAT |a'|^2 + |b'|^2 = 1
    norm_psi = np.array([alpha,beta])/np.sqrt(abs(alpha)**2+abs(beta)**2)
    # RETURN A VECTOR
    return norm_psi

or

    # CREATE A VECTOR [a', b'] BASED ON alpha AND beta SUCH THAT |a'|^2 + |b'|^2 = 1
    psi = np.array([alpha,beta])
    norm_psi = psi/np.sqrt(np.dot(psi,psi))
    # RETURN A VECTOR
    return norm_psi

Source code

No response

Tracebacks

No response

Check other issues

• [X] I have searched existing GitHub issues to make sure the issue does not already exist.

Feature details

P.3.2 seems to have a typo (as detailed here) in the explanation of the desired output.

Current: “”" Returns: [(float, float)]: a list of phase windows for 1 to 9 estimation wires “”"

Fixed: “”" Returns: [(float, float)]: a list of phase windows for “2” to 9 estimation wires “”"

Additional information

No response

Feature details

As detailed here, the grader is taking bound 1 and bound 2 in the reverse order. We should either change the grader, the description of the bounds or the order in which they are returned.

Additional information

No response

Feature details

Is there a way I can access any code that I have done in one desktop to a laptop without having to restart my laptop?

Additional information

No response