# CVObservable¶

Module: pennylane

class CVObservable(*args, wires=None, do_queue=True)[source]

Base class for continuous-variable observables.

The class attribute ev_order can be defined to indicate to PennyLane whether the corresponding CV observable is a polynomial in the quadrature operators. If so,

• ev_order = 1 indicates a first order polynomial in quadrature operators $$(\x, \p)$$.
• ev_order = 2 indicates a second order polynomial in quadrature operators $$(\x, \p)$$.

If ev_order is not None, then the Heisenberg representation of the observable should be defined in the static method _heisenberg_rep(), returning an array of the correct dimension.

ev_order = None

if not None, the observable is a polynomial of the given order in (x, p).

Type: None, int
heisenberg_obs(num_wires)[source]

Representation of the observable in the position/momentum operator basis.

Returns the expansion $$q$$ of the observable, $$Q$$, in the basis $$\mathbf{r} = (\I, \x_0, \p_0, \x_1, \p_1, \ldots)$$.

• For first-order observables returns a real vector such that $$Q = \sum_i q_i \mathbf{r}_i$$.
• For second-order observables returns a real symmetric matrix such that $$Q = \sum_{ij} q_{ij} \mathbf{r}_i \mathbf{r}_j$$.
Parameters: num_wires (int) – total number of wires in the quantum circuit $$q$$ array[float]