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].

Parameter

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

• kwargs – optional arguments to pass to CVXPY solver.

Rückgabe

The completely-bounded trace norm

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

Rückgabetyp

float

Verursacht

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).

Bemerkung

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.