All Questions
6 questions
2votes
2answers
739views
Change of basis in bra-ket notation [duplicate]
In the post Change of Basis in quantum mechanics using Bra-Ket notation , the accepted answer explores the relationship between an arbitrary operator $\hat{x}$ and another named $\hat{u}$, such that $\...
- 307
0votes
2answers
356views
Does an orthonormal basis imply hermiticity of operator?
I am confused as to what hermiticity of an operator means when given a basis set. My course notes say that hermitian operators in Hilbert space stay unchanged under it's complex conjugate: $$<n|A|m&...
- 43
0votes
2answers
96views
Dirac notation notation equality
I'm going trough my quantum mechanics notes but I don't understand why: $$H|\phi_{m}\rangle\langle\phi_{n}|-|\phi_{m}\rangle\langle\phi_{n}|H=a_{m}\langle\phi_{n}|-a_{n}|\phi_{m}\rangle.$$ What is ...
0votes
1answer
162views
Need help understanding product of Kronecker delta function with an outer product
I need help solving the the below expression which is from the book Modern Quantum Mechanics by J. J. Sakurai and Jim Napolitano. $$A=\sum_{a''}\sum_{a'}|a''\rangle a'\delta_{a'a''}\langle a'| =~?$$ I ...
0votes
1answer
53views
What do I get by multiplying a 0 operator on a 0 eigenvector?
I don't know how to write the equation form. Assuming my notation as Dirac notation, what do I get from $$ ( 0 | 0 | 0 ) ~?$$
3votes
3answers
455views
Trouble with position operator in quantum mechanics
I'm having some trouble with understanding the derivation of the action of the $X$ operator. It seems to be a result of the notation used and not a property of itself. The usual argument is to ...
- 365
