Note

This is the documentation for the current state of the development branch of Qiskit Experiments. The documentation or APIs here can change prior to being released.

MockIQExperimentHelper.compute_probabilities

abstract MockIQExperimentHelper.compute_probabilities(circuits)

A function provided by the user which is used to determine the probability of each output of the circuit. The function returns a list of dictionaries, each containing output binary strings and their probabilities.

Examples:

1 qubit circuit - excited state

In this experiment, we want to bring a qubit to its excited state and measure it. The circuit:

     ┌───┐┌─┐
q:   ┤ X ├┤M├
     └───┘└╥┘
c: 1/══════╩═
            0

The function that calculates the probability for this circuit doesn’t need any calculation parameters:

@staticmethod
def compute_probabilities(self, circuits: List[QuantumCircuit])
    -> List[Dict[str, float]]:

    output_dict_list = []
    for circuit in circuits:
        probability_output_dict = {"1": 1.0, "0": 0.0}
        output_dict_list.append(probability_output_dict)
    return output_dict_list

3 qubit circuit

In this experiment, we prepare a Bell state with the first and second qubit. In addition, we will bring the third qubit to its excited state. The circuit:

        ┌───┐     ┌─┐
q_0:    ┤ H ├──■──┤M├───
        └───┘┌─┴─┐└╥┘┌─┐
q_1:    ─────┤ X ├─╫─┤M├
        ┌───┐└┬─┬┘ ║ └╥┘
q_2:    ┤ X ├─┤M├──╫──╫─
        └───┘ └╥┘  ║  ║
c:    3/═══════╩═══╩══╩═
            2   0  1

When an output string isn’t in the probability dictionary, the backend will assume its probability is 0.

@staticmethod
def compute_probabilities(self, circuits: List[QuantumCircuit])
    -> List[Dict[str, float]]:

    output_dict_list = []
    for circuit in circuits:
        probability_output_dict = {}
        probability_output_dict["001"] = 0.5
        probability_output_dict["111"] = 0.5
        output_dict_list.append(probability_output_dict)
    return output_dict_list

Return type:

List[Dict[str, Any]]