sf.ops.MeasureFock

class MeasureFock(select=None, dark_counts=None)

Bases: strawberryfields.ops.Measurement

Photon counting measurement: measures a set of modes in the Fock basis.

Also accessible via the shortcut variable Measure.

After measurement, the modes are reset to the vacuum state.

Warning

Photon counting is available in the Gaussian backend, but the state of the circuit is not updated after measurement (since it would be non-Gaussian).

Details and Conventions

Definition

Photon counting is a non-Gaussian projective measurement given by

\[\ket{n_i}\bra{n_i}\]

Attributes

measurement_deps	Extra dependencies due to parameters that depend on measurements.
ns

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 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 backend to execute the operation on the current register state right away.

Like Operation.apply(), but also stores the measurement result in the RegRefs.

Keyword Arguments

shots (int) – Number of independent evaluations to perform. Only applies to Measurements.

decompose(reg, **kwargs)

Decompose the operation into elementary operations supported by the backend API.

See strawberryfields.backends.base.

Parameters

reg (Sequence[RegRef]) – subsystems the operation is acting on

Returns

decomposition as a list of operations acting on specific subsystems

Return type

list[Command]

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

code/api/strawberryfields.ops.MeasureFock

 

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