I think it is a good way to map what people have commonly called “superposition,” but the sentence should probably be “The system is in the superposition STATE1 + STATE2, relative to STATE 3, where STATE 3 roughly factors out”. STATE 3 in this case is usually an observer. I mean, if I flip a “quantum coin” and I have not told you if it is heads or tails, then the coin (and I) is in a superposition of “HEADS + TAILS” relative to you, but due to decoherence on my end, it is not in a superposition relative to me. For me this was an important concept to learn, as it helped me see that “many worlds” is a local and non-discrete phenomenon.
I think it is a good way to map what people have commonly called “superposition,” but the sentence should probably be “The system is in the superposition STATE1 + STATE2, relative to STATE 3, where STATE 3 roughly factors out”. STATE 3 in this case is usually an observer. I mean, if I flip a “quantum coin” and I have not told you if it is heads or tails, then the coin (and I) is in a superposition of “HEADS + TAILS” relative to you, but due to decoherence on my end, it is not in a superposition relative to me. For me this was an important concept to learn, as it helped me see that “many worlds” is a local and non-discrete phenomenon.