Scott: I’m a bit confused by what you’re doing here: TrA[UA ρAB UA*] = ρB
Specifically, I understand what a trace is, but what’s TrA mean? ie, I’m guessing it’s not a scalar given that it looks like multiplying (if that’s the intended operation) it by the transformed density matrix of AB gives you a density matrix of B, which presumably has fewer dimensions.
Scott: I’m a bit confused by what you’re doing here: TrA[UA ρAB UA*] = ρB
Specifically, I understand what a trace is, but what’s TrA mean? ie, I’m guessing it’s not a scalar given that it looks like multiplying (if that’s the intended operation) it by the transformed density matrix of AB gives you a density matrix of B, which presumably has fewer dimensions.