In the MCU, the Quantum Realm is a separate dimension. The main ways of accessing it (that we know of so far) are via Pym Particles (which power Ant-Man's suit) or via a Quantum Tunnel.

It has now been demonstrated in the incredibly tiny quantum realm. Researchers detail an ... Quantum scars make their mark In physics, these unique electron orbits are known as "quantum scars." ...

new findings show that time can flow in opposite directions in the quantum realm. A study conducted by scientists from the School of Mathematics and Physics, University of Surrey in the UK ...

Michalakis described the Quantum Realm as “a place of infinite possibility, an alternative universe where the laws of physics and the forces of nature as we know them haven’t crystallized.” ...

The science says all of this is possible,” says Michalakis. The quantum realm, Michalakis says, is a sort of hackable “source code of reality.” And “quantum physics says you’re allowed to do anything ...

Patterns in chaos have been proven, in the incredibly tiny quantum realm, by an international ... carrying information from one end to the other." In physics, these unique electron orbits are ...