# qml.devices.default_gaussian.fock_expectation¶

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

Calculates the expectation and variance of a Fock state probability.

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

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

• params (Sequence[int]) – the Fock state to return the expectation value for

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

Returns

the Fock state expectation and variance

Return type

tuple