ReadoutError#

class ReadoutError(probabilities, atol=1e-08)[source]#

Bases: object

Readout error class for Aer noise model.

Create a readout error for a noise model.

For an N-qubit readout error probabilities are entered as vectors:

probabilities[m] = [P(0|m), P(1|m), ..., P(2 ** N - 1|m)]

where P(n|m) is the probability of recording a noisy measurement outcome as n given the true ideal measurement outcome was m, where n and m are integer representations of bit-strings.

Example: 1-qubit

probabilities[0] = [P("0"|"0"), P("1"|"0")]
probabilities[1] = [P("0"|"1"), P("1"|"1")]

Example: 2-qubit

probabilities[0] = [P("00"|"00"), P("01"|"00"), P("10"|"00"), P("11"|"00")]
probabilities[1] = [P("00"|"01"), P("01"|"01"), P("10"|"01"), P("11"|"01")]
probabilities[2] = [P("00"|"10"), P("01"|"10"), P("10"|"10"), P("11"|"10")]
probabilities[3] = [P("00"|"11"), P("01"|"11"), P("10"|"11"), P("11"|"11")]
Parameters:

  • probabilities (matrix) – List of outcome assignment probabilities.

  • atol (double) – Threshold for checking probabilities are normalized (Default: 1e-8).

Raises:

NoiseError – if an invalid argument is provided

Attributes

atol#

The default absolute tolerance parameter for float comparisons.

num_qubits#

Return the number of qubits.

number_of_qubits#

Return the number of qubits for the error.

probabilities#

Return the readout error probabilities matrix.

rtol#

The relative tolerance parameter for float comparisons.

Methods

__mul__(other)[source]#
compose(other, front=False)[source]#

Return the composition readout error other * self.

Note that for front=True this is equivalent to the ReadoutError.dot() method.

Parameters:

  • other (ReadoutError) – a readout error.

  • front (bool) – If True return the reverse order composation self * other instead [default: False].

Returns:

The composition readout error.

Return type:

ReadoutError

Raises:

  • NoiseError – if other is not a ReadoutError or has incompatible

  • dimensions. –

copy()[source]#

Make a copy of current ReadoutError.

dot(other)[source]#

Return the composition readout error self * other.

Parameters:

other (ReadoutError) – a readout error.

Returns:

The composition readout error.

Return type:

ReadoutError

Raises:

  • NoiseError – if other is not a ReadoutError or has incompatible

  • dimensions. –

expand(other)[source]#

Return the tensor product readout error self ⊗ other.

Parameters:

other (ReadoutError) – a readout error.

Returns:

the tensor product readout error other ⊗ self.

Return type:

ReadoutError

Raises:

NoiseError – if other is not a ReadoutError.

ideal()[source]#

Return True if current error object is an identity

power(n)[source]#

Return the compose of the readout error with itself n times.

Parameters:

n (int) – the number of times to compose with self (n>0).

Returns:

the n-times composition channel.

Return type:

ReadoutError

Raises:

NoiseError – if the power is not a positive integer.

classmethod set_atol(value)[source]#

Set the class default absolute tolerance parameter for float comparisons.

classmethod set_rtol(value)[source]#

Set the class default relative tolerance parameter for float comparisons.

tensor(other)[source]#

Return the tensor product readout error self ⊗ other.

Parameters:

other (ReadoutError) – a readout error.

Returns:

the tensor product readout error self ⊗ other.

Return type:

ReadoutError

Raises:

NoiseError – if other is not a ReadoutError.

to_dict()[source]#

Return the current error as a dictionary.

to_instruction()[source]#

Convert the ReadoutError to a circuit Instruction.