sf.ops.ThermalLossChannel¶

class
ThermalLossChannel
(T, nbar)[source]¶ Bases:
strawberryfields.ops.Channel
Perform a thermal loss channel operation on the specified mode.
This channel couples mode \(\a\) to another bosonic mode \(\hat{b}\) prepared in a thermal state with mean photon number \(\bar{n}\), using the following transformation:
\[\a \mapsto \sqrt{T} a+\sqrt{1T} \hat{b}\] Parameters
T (float) – the loss parameter \(0\leq T\leq 1\).
nbar (float) – mean photon number of the environment thermal state
Details and conventions
Definition
Thermal loss is implemented by coupling mode \(\a\) to another bosonic mode \(\hat{b}\) prepared in the thermal state \(\ket{\bar{n}}\), by using the following transformation
\[\a \to \sqrt{T} \a+\sqrt{1T} \hat{b}\]and then tracing it out. Here, \(T\) is the energy transmissivity. For \(T = 0\) the state is mapped to the thermal state \(\ket{\bar{n}}\) with mean photon number \(\bar{n}\), and for \(T=1\) one has the identity map.
Note that if \(\bar{n}=0\), the thermal loss channel is equivalent to the loss channel.
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
= 1¶
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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