reestablish fundamental brakets

    spin Z operators

    raising/lowering operators (lowering erased before pic)

    commutations relations (erased before pic)

Now setup a two-spin system

    (pic) Look at general operator expressions ?? in different spaces ??

    Take direct product of A and B

(pic) Developed 𝐒 using raising lowering operators

    (pic: last y should be an x) Proved this.