QuantumError
class QuantumError(noise_ops, number_of_qubits=None, standard_gates=None, atol=None)
Bases: qiskit.quantum_info.operators.base_operator.BaseOperator, qiskit.quantum_info.operators.mixins.tolerances.TolerancesMixin
Quantum error class for Qiskit Aer noise model
WARNING: The init interface for this class is not finalized and may
change in future releases. For maximum backwards compatibility use the QuantumError generating functions in the noise.errors module.
Create a quantum error for a noise model.
Noise ops may either be specified as a QuantumChannel for a general CPTP map, or as a list of (circuit, p) pairs where circuit is a circuit-like object for the noise, and p is the probability of the noise event. Any type of input will be converted to the probabilistic mixture of circuit format.
Example
An example noise_ops for a bit-flip error with error probability p = 0.1 is:
noise_ops = [(IGate(), 0.9),
(XGate(), 0.1)]or specifying explicit qubit arguments,
noise_ops = [((IGate(), [0]), 0.9),
((XGate(), [0]), 0.1)]The same error represented as a Kraus channel can be input as:
noise_ops = Kraus([np.sqrt(0.9) * np.array([[1, 0], [0, 1]]),
np.sqrt(0.1) * np.array([[0, 1], [1, 0]])])Parameters
- noise_ops (QuantumChannel or Iterable) – Either a quantum channel or a list of
(circuit, p)pairs, which represents a quantum error, wherecircuitis a circuit-like object for the noise, andpis the probability of the noise event. Circuit-like types includeQuantumCircuit,(Instruction, qargs)and a list of(Instruction, qargs). Note thatqargsshould be a list of integers and can be omitted (default qubits are used in that case). See also examples above. - number_of_qubits (int) – [DEPRECATED] specify the number of qubits for the error. If None this will be determined automatically (default None).
- standard_gates (bool) – [DEPRECATED] Check if input matrices are standard gates.
- atol (double) – [DEPRECATED] Threshold for testing if probabilities are equal to 0 or 1 (Default:
QuantumError.atol).
Raises
NoiseError – If input noise_ops is invalid, e.g. it’s not a CPTP map.
Methods
compose
QuantumError.compose(other, qargs=None, front=False)
Return the operator composition with another CLASS.
Parameters
- other (CLASS) – a CLASS object.
- qargs (list or None) – Optional, a list of subsystem positions to apply other on. If None apply on all subsystems (default: None).
- front (bool) – If True compose using right operator multiplication, instead of left multiplication [default: False].
Returns
The composed CLASS.
Return type
CLASS
Raises
QiskitError – if other cannot be converted to an operator, or has incompatible dimensions for specified subsystems.
Composition (&) by default is defined as left matrix multiplication for matrix operators, while dot() is defined as right matrix multiplication. That is that A & B == A.compose(B) is equivalent to B.dot(A) when A and B are of the same type.
Setting the front=True kwarg changes this to right matrix multiplication and is equivalent to the dot() method A.dot(B) == A.compose(B, front=True).
copy
QuantumError.copy()
Make a copy of current QuantumError.
dot
QuantumError.dot(other, qargs=None)
Return the right multiplied operator self * other.
Parameters
- other (Operator) – an operator object.
- qargs (list or None) – Optional, a list of subsystem positions to apply other on. If None apply on all subsystems (default: None).
Returns
The right matrix multiplied Operator.
Return type
error_term
QuantumError.error_term(position)
Return a single term from the error.
Parameters
position (int) – the position of the error term.
Returns
A pair (circuit, p) for error term at position < size where p is the probability of the error term, and circuit is the list of qobj instructions for the error term.
Return type
tuple
Raises
- NoiseError – If the position is greater than the size of
- the quantum error. –
expand
QuantumError.expand(other)
Return the reverse-order tensor product with another CLASS.
Parameters
other (CLASS) – a CLASS object.
Returns
the tensor product , where
is the current CLASS, and is the other CLASS.
Return type
CLASS
ideal
QuantumError.ideal()
Return True if this error object is composed only of identity operations. Note that the identity check is best effort and up to global phase.
input_dims
QuantumError.input_dims(qargs=None)
Return tuple of input dimension for specified subsystems.
output_dims
QuantumError.output_dims(qargs=None)
Return tuple of output dimension for specified subsystems.
power
QuantumError.power(n)
Return the compose of a operator with itself n times.
Parameters
n (int) – the number of times to compose with self (n>0).
Returns
the n-times composed operator.
Return type
Raises
QiskitError – if the input and output dimensions of the operator are not equal, or the power is not a positive integer.
reshape
QuantumError.reshape(input_dims=None, output_dims=None, num_qubits=None)
Return a shallow copy with reshaped input and output subsystem dimensions.
Parameters
- input_dims (None or tuple) – new subsystem input dimensions. If None the original input dims will be preserved [Default: None].
- output_dims (None or tuple) – new subsystem output dimensions. If None the original output dims will be preserved [Default: None].
- num_qubits (None or int) – reshape to an N-qubit operator [Default: None].
Returns
returns self with reshaped input and output dimensions.
Return type
BaseOperator
Raises
QiskitError – if combined size of all subsystem input dimension or subsystem output dimensions is not constant.
set_atol
classmethod QuantumError.set_atol(value)
Set the class default absolute tolerance parameter for float comparisons.
set_rtol
classmethod QuantumError.set_rtol(value)
Set the class default relative tolerance parameter for float comparisons.
tensor
QuantumError.tensor(other)
Return the tensor product with another CLASS.
Parameters
other (CLASS) – a CLASS object.
Returns
the tensor product , where
is the current CLASS, and is the other CLASS.
Return type
CLASS
The tensor product can be obtained using the ^ binary operator. Hence a.tensor(b) is equivalent to a ^ b.
to_dict
QuantumError.to_dict()
Return the current error as a dictionary.
to_instruction
QuantumError.to_instruction()
Convert the QuantumError to a circuit Instruction.
to_quantumchannel
QuantumError.to_quantumchannel()
Convert the QuantumError to a SuperOp quantum channel. Required to enable SuperOp(QuantumError).
Attributes
atol
Default value: 1e-08
circuits
Return the list of error circuits.
dim
Return tuple (input_shape, output_shape).
id
Return unique ID string for error
num_qubits
Return the number of qubits if a N-qubit operator or None otherwise.
number_of_qubits
Return the number of qubits for the error.
probabilities
Return the list of error probabilities.
qargs
Return the qargs for the operator.
rtol
Default value: 1e-05
size
Return the number of error circuit.