Quantum's rhymes with:
bantam's, bantams, phantoms, ageratums, argosystems, atoms, autumn's, bantam's, bantams, biosystems, bottom's, bottoms, cablesystems, customs, ecosystems, items, microsystems, microsystems', mortems, phantoms, subsystems, symptoms, system's, systems, systems', techsystems, totems, ultimatums, ultrasystems, victim's, victims