sf.ops.Ket¶
-
class
Ket
(state)[source]¶ Bases:
strawberryfields.ops.Preparation
Prepare mode(s) using the given ket vector(s) in the Fock basis.
The prepared modes are traced out and replaced with the given ket state (in the Fock basis). As a result the state of the other subsystems may have to be described using a density matrix.
The provided kets must be each be of length
cutoff_dim
, matching the cutoff dimension used in calls toeng.run
.Warning
The Fock basis is non-Gaussian, and thus can only be used in the Fock backends, not the Gaussian backend.
- Parameters
state (array or BaseFockState) –
state vector in the Fock basis. This can be provided as either:
a single ket vector, for single mode state preparation
a multimode ket, with one array dimension per mode
a
BaseFockState
state object.
Details and Conventions
Definition
A single mode state can be decomposed into the Fock basis as follows:
\[\ket{\psi} = \sum_n c_n \ket{n}\]Attributes
Extra dependencies due to parameters that depend on measurements.
-
measurement_deps
¶ Extra dependencies due to parameters that depend on measurements.
- Returns
dependencies
- Return type
set[RegRef]
-
ns
= None¶
Methods
apply
(reg, backend, **kwargs)Ask a local backend to execute the operation on the current register state right away.
decompose
(reg, **kwargs)Decompose the operation into elementary operations supported by the backend API.
merge
(other)Merge the operation with another (acting on the exact same set of subsystems).
-
apply
(reg, backend, **kwargs)¶ Ask a local backend to execute the operation on the current register state right away.
Takes care of parameter evaluations and any pending formal transformations (like dagger) and then calls
Operation._apply()
.- Parameters
reg (Sequence[RegRef]) – subsystem(s) the operation is acting on
backend (BaseBackend) – backend to execute the operation
- Returns
the result of self._apply
- Return type
Any
-
decompose
(reg, **kwargs)¶ Decompose the operation into elementary operations supported by the backend API.
See
strawberryfields.backends.base
.
-
merge
(other)¶ Merge the operation with another (acting on the exact same set of subsystems).
Note
For subclass overrides: merge may return a newly created object, or self, or other, but it must never modify self or other because the same Operation objects may be also used elsewhere.
- Parameters
other (Operation) – operation to merge this one with
- Returns
other * self. The return value None represents the identity gate (doing nothing).
- Return type
Operation, None
- Raises
MergeFailure – if the two operations cannot be merged