Non-binary memory based on quantum effects

NAND Flash memory is made using floating gate transistors. This means that the gates to the transistors are electrically isolated from any other contact on the transistor. Quantum tunneling is used to deposit electrons on the gate, changing the transistor state. When many electrons are located on the gate, the transistor is on and stores a logical 1. When the gate has few electrons, the transistor is off and stores a logical 0. Changing the number of electrons on the gate is done by applying a voltage across the gate that sufficient to induce electron tunneling between an electrode and the isolated gate.

Newer forms of NAND flash actually store multiple bits on each transistor. Different levels of electrons on the gate correspond to different values, and the number of bits represented corresponds to the different number of discern-able electron levels (n bits = log2(n) electron levels).

A lot of thumb drives are made using NAND flash, which means people are just carrying around non-binary memory that makes use of quantum effects.

I think it's pretty clear that we already live in the future.