quairkit.qinfo.check¶

quairkit.qinfo.check.is_choi(op)¶

Check if the input op is a Choi operator of a physical operation.: Support batch input.

Parameters:¶

op : ndarray | Tensor¶: matrix form of the linear operation.

Returns:¶

Whether the input op is a valid quantum operation Choi operator. For batch input, return a boolean array with the same batch dimensions as input.

Return type:¶

bool | List[bool]

Note

The operation op is (default) applied to the second system.

quairkit.qinfo.check.is_density_matrix(rho, eps=1e-06)¶

Verify whether rho is a legal quantum density matrix: Support batch input

Parameters:¶

rho : ndarray | Tensor¶: density matrix candidate
eps : float | None¶: tolerance of error, default to be None i.e. no testing for data correctness

Returns:¶

determine whether rho is a PSD matrix with trace 1

Return type:¶

bool | List[bool]

quairkit.qinfo.check.is_hermitian(mat, eps=1e-06)¶

Verify whether mat is Hermitian.: Support batch input.

Parameters:¶

mat : ndarray | Tensor¶: hermitian candidate \(P\)
eps : float | None¶: tolerance of error

Returns:¶

determine whether \(P - P^\dagger = 0\) For batch input, return a boolean array with the same batch dimensions as input.

Return type:¶

bool | List[bool]

quairkit.qinfo.check.is_linear(func, info, input_dtype=None, eps=1e-05)¶

Check if the provided function ‘func’ is linear.

Parameters:¶

func : Callable[[Tensor | ndarray], Tensor | ndarray]¶: A callable function to be tested. This function should accept and return either a torch.Tensor or a numpy.ndarray.
info : List[int] | Callable[[], ndarray] | Callable[[], Tensor]¶: A parameter specifying the shape of the input for ‘func’. It can be a list of two integers (defining the shape of a tensor), a callable that returns a numpy.ndarray, or a callable that returns a torch.Tensor.
eps : float | None¶: An optional tolerance value used to determine if the function’s behavior is close enough to linear. Default value is 1e-6.

Returns:¶

True if ‘func’ behaves as a linear function within the specified tolerance ‘eps’; False otherwise.

Return type:¶

bool

Raises:¶

TypeError – If ‘func’ is not callable, does not accept a torch.Tensor or numpy.ndarray as input, or does not return a torch.Tensor or numpy.ndarray. If ‘info’ is not a valid type (not a list of integers or a callable returning a torch.Tensor or numpy.ndarray).

quairkit.qinfo.check.is_positive(mat, eps=1e-06)¶

Verify whether mat is a positive semi-definite matrix.: Support batch input.

Parameters:¶

mat : ndarray | Tensor¶: positive operator candidate \(P\)
eps : float | None¶: tolerance of error

Returns:¶

determine whether \(P\) is Hermitian and eigenvalues are non-negative For batch input, return a boolean array with the same batch dimensions as input.

Return type:¶

bool | List[bool]

quairkit.qinfo.check.is_povm(set_op, eps=1e-06)¶

Check if a set of operators forms a positive operator-valued measure (POVM).

Parameters:¶

set_op : Tensor | ndarray¶: A set of operators indexed by the first dimension
eps : float | None¶: An optional tolerance value. Default value is 1e-6.

Returns:¶

whether the operators form a POVM.

Return type:¶

bool | List[bool]

quairkit.qinfo.check.is_projector(mat, eps=1e-06)¶

Verify whether mat is a projector.: Support batch input.

Parameters:¶

mat : ndarray | Tensor¶: projector candidate \(P\)
eps : float | None¶: tolerance of error

Returns:¶

determine whether \(PP - P = 0\) For batch input, return a boolean array with the same batch dimensions as input.

Return type:¶

bool | List[bool]

quairkit.qinfo.check.is_ppt(density_op)¶

Check if the input quantum state is PPT.: Support batch input.

Parameters:¶

density_op : ndarray | Tensor | State¶: Density matrix form of the quantum state.

Returns:¶

Whether the input quantum state is PPT. For batch input, return a boolean array with the same batch dimensions as input.

Return type:¶

bool | List[bool]

quairkit.qinfo.check.is_pvm(set_op, eps=1e-06)¶

Check if a set of operators forms a projection-valued measure (PVM).

Parameters:¶

set_op : Tensor | ndarray¶: A set of operators indexed by the first dimension
eps : float | None¶: An optional tolerance value. Default value is 1e-6.

Returns:¶

True if the operators form a PVM; otherwise, False.

Return type:¶

bool or List[bool]

quairkit.qinfo.check.is_state_vector(vec, eps=1e-06)¶

Verify whether vec is a legal quantum state vector.: Support batch input.

Parameters:¶

vec : ndarray | Tensor¶: state vector candidate \(x\)
eps : float | None¶: tolerance of error, default to be None i.e. no testing for data correctness

Returns:¶

determine whether \(x^\dagger x = 1\)

Return type:¶

bool | List[bool]

quairkit.qinfo.check.is_unitary(mat, eps=0.0001)¶

Verify whether mat is a unitary.: Support batch input.

Parameters:¶

mat : ndarray | Tensor¶: unitary candidate \(P\)
eps : float | None¶: tolerance of error

Returns:¶

determine whether \(PP^\dagger - I = 0\) For batch input, return a boolean array with the same batch dimensions as input.

Return type:¶

bool | List[bool]