Wavelength in QM: Definition & Measurement

[suku]

Can anyone tell me how is wavelength defined for a wave associated with a particle?
If the wave function we are speaking of has no physical significance,then how can measure its length?
tks for any rpl

 

[muppet]

By "wavelength" in QM one usually means the de Broglie wavelength, defined by
$$\lambda=\frac{h}{p}$$
where p is the momentum of a particle and h is Planck's constant.

The wavefunction is neither physically insignificant nor something you measure directly. For a basic introduction to what the wavefunction means, see the library article on wave-particle duality; for a more technical description see that on wave function.