qml.devices.default_gaussian.photon_number¶

photon_number(cov, mu, params, hbar=2.0)[source]¶

Calculates the mean photon number for a given one-mode state.

Parameters

• cov (array) – $2\times 2$ covariance matrix

• mu (array) – length-2 vector of means

• params (None) – no parameters are used for this expectation value

• hbar (float) – (default 2) the value of $\hbar$ in the commutation relation $[\x,\p]=i\hbar$

Returns

contains the photon number expectation and variance

Return type

tuple