Note

This is the documentation for the current state of the development branch of Qiskit Experiments. The documentation or APIs here can change prior to being released.

oscillation_exp_decay

oscillation_exp_decay(x, y, filter_window=5, filter_dim=2, freq_guess=None)

Get exponential decay parameter from oscillating signal.

This assumes following function form.

$$y(x)=e^{\alpha x}F(x),$$

where $F(x)$ is arbitrary oscillation function oscillating at freq_guess. This function first applies a Savitzky-Golay filter to y value, then run scipy peak search to extract peak positions. If freq_guess is provided, the search function will be robust to fake peaks due to noise. This function calls exp_decay() function for extracted x and y values at peaks.

Note

y values should contain more than one cycle of oscillation to use this guess approach.

Parameters:

• x (ndarray) – Array of x values.

• y (ndarray) – Array of y values.

• filter_window (int) – Window size of Savitzky-Golay filter. This should be odd number.

• filter_dim (int) – Dimension of Savitzky-Golay filter.

• freq_guess (Optional[float]) – Optional. Initial frequency guess of $F(x)$.

Return type:

float

Returns:

Decay rate of signal.