I never claimed that it was, quantum computers are still experimental.

Yet you linked the article that made that statement and then refuted it!

Quote from the article you linked:

https://qt.eu/applications/how-your-smartphone-uses-quantum-mechanics

Where it gives an example of how your phone uses quantum mechanics.

which was explained by Albert Einstein by introducing quanta of light,

Yes a photon. Light is photons. The light from a caveman fire is photons. I already explained that.