hellinger_fidelity¶

hellinger_fidelity(dist_p, dist_q)[source]¶

Computes the Hellinger fidelity between two counts distributions.

The fidelity is defined as 1-H where H is the Hellinger distance. This value is bounded in the range [0, 1].

Parameters

dist_p (dict) – First dict of counts.
dist_q (dict) – Second dict of counts.

Returns

Fidelity

Return type

float

Example

from qiskit import QuantumCircuit, execute, BasicAer
from qiskit.quantum_info.analysis import hellinger_fidelity

qc = QuantumCircuit(5, 5)
qc.h(2)
qc.cx(2, 1)
qc.cx(2, 3)
qc.cx(3, 4)
qc.cx(1, 0)
qc.measure(range(5), range(5))

sim = BasicAer.get_backend('qasm_simulator')
res1 = execute(qc, sim).result()
res2 = execute(qc, sim).result()

hellinger_fidelity(res1.get_counts(), res2.get_counts())

1.0