qrisp.QuantumVariable.get_measurement#

QuantumVariable.get_measurement(plot=False, backend=None, shots=None, compile=True, compilation_kwargs={}, subs_dic={}, circuit_preprocessor=None, filename=None, precompiled_qc=None) → DecodedMeasurementResult[source]#

Get the measurement results of the state of the variable.

Method for quick access to the measurement results of the state of the variable. Returns a DecodedMeasurementResult, which behaves like a dictionary of the type {value: p} where p is the measurement probability.

Parameters:

plotBool, optional: Plots the measurement results as a historgram. The default is False.
backendBackendLike, optional: The backend on which to evaluate the quantum circuit. The default can be specified in the file default_backend.py.
shotsinteger, optional: The amount of shots to evaluate the circuit. The default is given by the backend it runs on.
compilebool, optional: Boolean indicating if the .compile method of the underlying QuantumSession should be called before. The default is True.
compilation_kwargsdict, optional: Keyword arguments for the compile method. For more details check QuantumSession.compile. The default is {}.
subs_dicdict, optional: A dictionary of Sympy symbols and floats to specify parameters in the case of a circuit with unspecified, abstract parameters. The default is {}.
circuit_preprocessorPython function, optional: A function which recieves a QuantumCircuit and returns one, which is applied after compilation and parameter substitution. The default is None.
filenamestring, optional: The location of where to save a generated plot. The default is None.
precompiled_qcQuantumCircuit, optional: A circuit that has already been compiled from the containing QuantumSession. If given, it is used (as a copy) instead of compiling the session, and compile and compilation_kwargs are ignored. Parameter binding and circuit_preprocessor are still applied. The circuit must contain the qubits of this QuantumVariable. The default is None.

Returns:

DecodedMeasurementResult: A lazy DecodedMeasurementResult mapping each decoded value to its measurement probability.

Raises:

Exception: If the containing QuantumSession is in a quantum environment, it is not possible to execute measurements.
TracingModeError: If the QuantumVariable is registered in a TracingQuantumSession (i.e. while tracing), measurements are not supported.

Examples

We create an integer QuantumFloat, encode the value 1 and bring the qubit with significance 2 in superposition. We utilize the Qiskit transpiler by transpiling into the gate set \(\{\text{CX}, \text{U}\}\)

>>> from qrisp import QuantumFloat, h
>>> qf = QuantumFloat(3,-1)
>>> qf[:] = 1
>>> h(qf[2])
>>> mes_results = qf.get_measurement(circuit_preprocessor=lambda qc: qc.transpile(basis_gates=["cx", "u"]))
>>> print(mes_results)
{1.0: 0.5, 3.0: 0.5}