[BUG] ComplexWarnings in various demos

[mudit2812]

Issue description

Many demos have complex warnings present, with some demos even having multiple complex warnings present.

Expected behavior: (What you expect to happen)
No warnings are expected

Actual behavior: (What actually happens)
The following demos have ComplexWarnings:

• tutorial_eqnn_force_field: 1 warning
• tutorial_here_comes_the_sun: 1 warning
• tutorial_pulse_programming101: 4 warnings
• tutorial_vqe_vqd: 34 warnings (yikes)

System information: (include your operating system, Python version, Sphinx version, etc.)

Source code and tracebacks

The warnings in all demos is from jax. Example warning:

/home/runner/work/qml/qml/venv/lib/python3.10/site-packages/jax/_src/lax/lax.py:2745: ComplexWarning: Casting complex values to real discards the imaginary part
  x_bar = _convert_element_type(x_bar, x.aval.dtype, x.aval.weak_type)

Additional information

[KetpuntoG]

In this demo qrom demo too
Also, note that the vqe_vqd will be published (from the marketing point of view) soon, so it would good to fix this issue if possible