qiskit.quantum_info.diamond_norm

diamond_norm(choi, **kwargs)

Return the diamond norm of the input quantum channel object.

This function computes the completely-bounded trace-norm (often referred to as the diamond-norm) of the input quantum channel object using the semidefinite-program from reference [1].

パラメータ

• choi (Choi or QuantumChannel) – a quantum channel object or Choi-matrix array.

• kwargs – optional arguments to pass to CVXPY solver.

戻り値

The completely-bounded trace norm

\(\|\mathcal{E}\|_{\diamond}\).

戻り値の型

float

例外

QiskitError – if CVXPY package cannot be found.

Additional Information:

The input to this function is typically not a CPTP quantum channel, but rather the difference between two quantum channels \(\|\Delta\mathcal{E}\|_\diamond\) where \(\Delta\mathcal{E} = \mathcal{E}_1 - \mathcal{E}_2\).

Reference:

J. Watrous. 「Simpler semidefinite programs for completely bounded norms」, arXiv:1207.5726 [quant-ph] (2012).

注釈

This function requires the optional CVXPY package to be installed. Any additional kwargs will be passed to the cvxpy.solve function. See the CVXPY documentation for information on available SDP solvers.