Add is_cptp predicate #4365
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Add is_cptp predicate #4365
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MichaelBroughton
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Jul 29, 2021
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Looks good. The only thing I would change is in the test if we could try and cut out the dependency on other library pieces if we can. Also might be useful:
A random set of kraus operators can be made by doing (Totally untested :P):
one_qubit_u = cirq.testing.random_unitary(8)
one_qubit_kraus = np.reshape(one_qubit_u[:, :2], (-1, 2, 2)) # make 4 2x2 kraus ops.or
two_qubit_u = cirq.testing.random_unitary(64)
two_qubit_kraaus = np.reshape(two_qubit_u[:, :4], (-1, 4, 4)) # make 16 4x4 kraus ops.
cirq-core/cirq/linalg/predicates.py
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| @@ -149,6 +149,21 @@ def is_normal(matrix: np.ndarray, *, rtol: float = 1e-5, atol: float = 1e-8) -> | |||
| return matrix_commutes(matrix, matrix.T.conj(), rtol=rtol, atol=atol) | |||
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| def is_cptp(kraus_ops: Sequence[np.ndarray], *, rtol: float = 1e-5, atol: float = 1e-8): | |||
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A reasonable way to ensure this is forward compatible with changing that choice is to force keyword args for kraus_ops. We can weaken it later that way if we decide to stick with it, or add other args if we want to extend.
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Good point - moved kraus_ops into kwargs.
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Added the recommended random tests. |
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rht
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As requested in quantumlib#4194. Can be used for quantumlib#2271. This predicate is meant to be invoked when constructing a channel to verify that the provided Kraus operators actually describe a valid quantum channel. Recommendations for cleaner `is_cptp` behavior or additional test cases are welcome.
harry-phasecraft
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Oct 31, 2024
As requested in quantumlib#4194. Can be used for quantumlib#2271. This predicate is meant to be invoked when constructing a channel to verify that the provided Kraus operators actually describe a valid quantum channel. Recommendations for cleaner `is_cptp` behavior or additional test cases are welcome.
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As requested in #4194. Can be used for #2271.
This predicate is meant to be invoked when constructing a channel to verify that the provided Kraus operators actually describe a valid quantum channel. Recommendations for cleaner
is_cptpbehavior or additional test cases are welcome.