DensityMatrix¶
- class DensityMatrix(data, dims=None)[source]¶
Bases:
qiskit.quantum_info.states.quantum_state.QuantumState
,qiskit.quantum_info.operators.mixins.tolerances.TolerancesMixin
DensityMatrix class
Initialize a density matrix object.
- Parameters
or (data (np.ndarray or list or matrix_like or QuantumCircuit) – qiskit.circuit.Instruction): A statevector, quantum instruction or an object with a
to_operator
orto_matrix
method from which the density matrix can be constructed. If a vector the density matrix is constructed as the projector of that vector. If a quantum instruction, the density matrix is constructed by assuming all qubits are initialized in the zero state.dims (int or tuple or list) – Optional. The subsystem dimension of the state (See additional information).
- Raises
QiskitError – if input data is not valid.
- Additional Information:
The
dims
kwarg can be None, an integer, or an iterable of integers.Iterable
– the subsystem dimensions are the values in the list with the total number of subsystems given by the length of the list.Int
orNone
– the leading dimension of the input matrix specifies the total dimension of the density matrix. If it is a power of two the state will be initialized as an N-qubit state. If it is not a power of two the state will have a single d-dimensional subsystem.
Methods
Return the conjugate of the density matrix.
Make a copy of current operator.
Return tuple of input dimension for specified subsystems.
Return a visualization of the Statevector.
Evolve a quantum state by an operator.
Return the tensor product state other ⊗ self.
Compute the expectation value of an operator.
Return the output density matrix of an instruction.
Return a computational basis state density matrix.
Return a tensor product of Pauli X,Y,Z eigenstates.
Return True if trace 1 and positive semidefinite.
Measure subsystems and return outcome and post-measure state.
Return the subsystem measurement probability vector.
Return the subsystem measurement probability dictionary.
Return the purity of the quantum state.
Reset state or subsystems to the 0-state.
Return a DensityMatrix with reversed subsystem ordering.
Sample a dict of qubit measurement outcomes in the computational basis.
Sample a list of qubit measurement outcomes in the computational basis.
Set the seed for the quantum state RNG.
Return the tensor product state self ⊗ other.
Convert the density matrix to dictionary form.
Convert to Operator
Return a statevector from a pure density matrix.
Return the trace of the density matrix.
Attributes
- atol = 1e-08¶
- data¶
Return data.
- dim¶
Return total state dimension.
- num_qubits¶
Return the number of qubits if a N-qubit state or None otherwise.
- rtol = 1e-05¶
- settings¶
Return settings.