sf.ops.BipartiteGraphEmbed¶

class
BipartiteGraphEmbed
(A, mean_photon_per_mode=1.0, edges=False, drop_identity=True, tol=1e06)[source]¶ Bases:
strawberryfields.ops.Decomposition
Embed a bipartite graph into an interferometer setup.
A bipartite graph is a graph that consists of two vertex sets \(U\) and \(V\), such that every edge in the graph connects a vertex between \(U\) and \(V\). That is, there are no edges between vertices in the same vertex set.
The adjacency matrix of an \(N\) vertex undirected bipartite graph is a \(N\times N\) symmetric matrix of the form
\[\begin{split}A = \begin{bmatrix}0 & B \\ B^T & 0\end{bmatrix}\end{split}\]where \(B\) is a \(N/2\times N/2\) matrix representing the (weighted) edges between the vertex set.
This operation decomposes an adjacency matrix into a sequence of two mode squeezers, beamsplitters, and rotation gates.
 Parameters
A (array) – Either an \(N\times N\) complex or real symmetric adjacency matrix \(A\), or an \(N/2\times N/2\) complex or real matrix \(B\) representing the edges between the vertex sets if
edges=True
.mean_photon_per_mode (float) – guarantees that the mean photon number in the pure Gaussian state representing the graph satisfies \(\frac{1}{N}\sum_{i=1}^N sinh(r_{i})^2 ==\) :code:
mean_photon
edges (bool) – set to
True
if argumentA
represents the edges \(B\) between the vertex sets rather than the full adjacency matrixdrop_identity (bool) – If
True
, decomposed gates with trivial parameters, such that they correspond to an identity operation, are removed.tol (float) – the tolerance used when checking if the input matrix is symmetric: \(AA^T <\) tol
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
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