mthree.classes.QuasiDistribution¶
- class QuasiDistribution(data, shots=None, mitigation_overhead=None)[source]¶
A dict-like class for representing quasi-probabilities.
- Parameters:
data (dict) – Input data.
shots (int) – Number shots taken to form quasi-distribution.
mitigation_overhead (float) – Overhead from performing mitigation.
Methods
expval([exp_ops])Compute expectation value from distribution.
expval_and_stddev([exp_ops])Compute expectation value and standard deviation estimate from distribution.
Takes a quasiprobability distribution and maps it to the closest probability distribution as defined by the L2-norm.
stddev()Compute standard deviation estimate from distribution.
- expval(exp_ops='')[source]¶
Compute expectation value from distribution.
- Parameters:
exp_ops (str or dict or list) – String or dict representation of diagonal qubit operators used in computing the expectation value.
- Returns:
Expectation value.
- Return type:
float
- Raises:
M3Error – Invalid type passed to exp_ops.
- expval_and_stddev(exp_ops='')[source]¶
Compute expectation value and standard deviation estimate from distribution.
- Parameters:
exp_ops (str or dict) – String or dict representation of diagonal qubit operators used in computing the expectation value.
- Returns:
Expectation value. float: Estimate of standard deviation upper-bound.
- Return type:
float
Notes
The dict operator format is a sparse diagonal format using bitstrings as the keys.
- nearest_probability_distribution(return_distance=False)[source]¶
Takes a quasiprobability distribution and maps it to the closest probability distribution as defined by the L2-norm.
- Parameters:
return_distance (bool) – Return the L2 distance between distributions.
- Returns:
Nearest probability distribution. float: Euclidean (L2) distance of distributions.
- Return type:
Notes
Method from Smolin et al., Phys. Rev. Lett. 108, 070502 (2012).