There are many practical applications of quantum mechanics.

The one that I remember foremost is tunneling to (dis)charge the floating gates on flash memory transistors, but that just scratches the surface.

"Flash memory chips found in USB drives use quantum tunneling to erase their memory cells."

https://en.m.wikipedia.org/wiki/Applications_of_quantum_mech...

This I did not know:

"It even exists in the simple light switch. The switch would not work if electrons could not quantum tunnel through the layer of oxidation on the metal contact surfaces."