New posts in Hilbert Space

Does every ray in the Hilbert space of a system correspond to one and only one physical state and vice versa?

Adding Angular Momenta Operators in QM

How does this boundary term go to zero in the derivation of momentum (QM)?

Does anything guarantee that a field theory will have a lower bound on energy, so that a vacuum exists?

Uniqueness of bra-ket correspondence

How does a linear operator act on a bra?

How can Schrödinger's cat be both dead and alive?

Can a Hermitian operator $A$ bring a wavefunction $|\psi \rangle$ out of Hilbert space?

Contradiction between aymptotically free particles in QFT and unlocalization

What is the spectrum of $\hat x \hat p + \hat p \hat x$?