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:

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:

Returns:

The composition readout error.

Return type:

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

• dimensions.

expand(other)[source]#

Return the tensor product readout error self ⊗ other.

Parameters:

Returns:

the tensor product readout error other ⊗ self.

Return type:

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:

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:

Returns:

the tensor product readout error self ⊗ other.

Return type: