quairkit.operator.special¶

The source file of the class for the special quantum operator.

class quairkit.operator.special.ResetState¶

The class to reset the quantum state. It will be implemented soon.

The forward function.

class quairkit.operator.special.Collapse(system_idx, desired_result=None, if_print=False, measure_basis=None)¶

The class to compute the collapse of the quantum state.

Parameters:¶

system_idx : int | Iterable[int]¶: list of systems to be collapsed.
desired_result : int | str¶: The desired result you want to collapse. Defaults to None meaning preserving all results,
computation. : and activate probabilistic
if_print : bool¶: whether print the information about the collapsed state. Defaults to False.
measure_basis : Tensor | None¶: The basis of the measurement. Defaults to the computational basis.

Raises:¶

NotImplementedError – If the basis of measurement is not z. Other bases will be implemented in future.

Note

When desired_result is None, Collapse does not support gradient calculation

forward(state)¶

Compute the collapse of the input state.

Parameters:¶

Returns:¶

The collapsed quantum state.

Return type:¶

State

class quairkit.operator.special.OneWayLOCC(list_unitary, system_idx=None, acted_system_dim=2, measure_basis=None)¶

A one-way LOCC protocol, where quantum measurement is modelled by a PVM and all channels are unitary channels.

Parameters:¶

list_unitary : Tensor¶: a batched tensor that represents all unitaries.
system_idx : Iterable[int] | int¶: Indices of the systems on which the protocol is applied. The first element in the list
measured. : indexes systems to be
acted_system_dim : List[int] | int¶: dimension of systems that unitary channels act on. Can be a list of system dimensions
case. : or an int representing the dimension of all systems. Defaults to be qubit
measure_basis : Tensor | None¶: The basis of the measurement. Defaults to the computational basis.

forward(state)¶

Compute the input state passing through the LOCC protocol.

Parameters:¶

Returns:¶

The collapsed quantum state.

Return type:¶

State

class quairkit.operator.special.QuasiOperation(list_channels, quasi_prob, system_idx=None, type_repr='gate', acted_system_dim=2)¶

A quantum protocol containing quasi-operations.

Parameters:¶

list_channels : Tensor¶: a batched tensor that represents all unitaries.
quasi_prob : Tensor¶: the quasi-probability distribution for this quasi-operation.
system_idx : Iterable[int] | int¶: indices of the systems on which the protocol is applied.
type_repr : str¶: one of 'choi', 'kraus', 'stinespring' or 'gate'. Defaults to 'gate'.
acted_system_dim : List[int] | int¶: dimension of systems that these channels act on. Can be a list of system dimensions
case. : or an int representing the dimension of all systems. Defaults to be qubit

forward(state)¶

Compute the input state passing through the quasi-operation.

Parameters:¶

Returns:¶

The collapsed quantum state.

Return type:¶

State