Observables, Density Matrix, Reduced Density Matrix, Entanglement Entropy

[@iitjamphysicsbyjourneyman6737]

Thanks...superb videos

[@truthfor6326]

56:42, why is |gs> = [ + ], |ex> = [ - ], it seems H = |L> = +1|gs>, H|ex> = -1|ex>, so why is not [|L> - |R>] the ground state?

[@gustavoaroeira7329]

Thank you!

[@rinaaxx7236]

Hi ,thank you for your videos ,
I just have a question for you , if I have a density matrix for an ensemble , a square unity matrix (without knowing the order of this matrix ) , how then can I find the entropy ?? Plz help me

[@drmitchellsphysicschannel2955]

The von Neumann entropy is S=-Tr[rho*ln(rho)] in terms of the density matrix, rho. To compute the log of a matrix you switch to its eigenbasis.

[@deltalima6703]

This video is like a car wreck. You cant look away, you just absorb everything.