This book has two types of material; both well done. The first could have been written decades ago, and is the "traditional" atomic physics. Where you start with the hydrogen atom, and investigate its spectroscopy with the Schrodinger equation. Then the book takes the next logical step by going to helium and thence to heavier atoms. LS and JJ coupling and other refinements. Such material is now quite well known and you need this for a solid background.

But the book also has much more recent material. On quantum computing using qubits. These attempt to use the quantum states of small groups of atoms, to perform computations fundamentally different from current digital efforts. Enough detail is given for you to appreciate the severe experimental travails of the field, and how much more remains to be done, if qubits are ever to become useful.