> We build quantum computers where? On a planet? That has? Gravity.

Yep. Earth.

But they are small for now. From https://en.wikipedia.org/wiki/Quantum_computing#Physical_rea...

> In late 2017 and early 2018 IBM, Intel, and Google each reported testing quantum processors containing 50, 49, and 72 qubits, respectively, all realized using superconducting circuits. By number of qubits, these circuits are approaching the range in which simulating their quantum dynamics is expected to become prohibitive on classical computers, although it has been argued that further improvements in error rates are needed to put classical simulation out of reach.