Timeline for How do I write an operator in Dirac notation?
Current License: CC BY-SA 3.0
14 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Mar 24, 2018 at 5:17 | comment | added | ostrichCamel | each ket.bra is an operator that could be written in some basis as a 3x3 matrix. If you know that $\langle i \lvert j \rangle=\delta_{ij}$ (Kronecker delta) for an orthonormal basis set, I think you should be able to work out how to write the matrix as a sum of ket.bra s. | |
| Mar 24, 2018 at 4:09 | comment | added | john | @ostrichCamel but isn't the sum of ket-bra means 3x3 matrix in this case?? | |
| Mar 23, 2018 at 21:44 | comment | added | ostrichCamel | no, the answer will not look like a matrix. It will be a sum of terms, a continuation of @WetSavannaAnimal aka Rod Vance's answer. the $\lvert \rangle$ represent column vectors and the $\langle \rvert$ represent their conjugate transposes (so complex conjugate row vectors). | |
| Mar 23, 2018 at 8:23 | comment | added | john | @ostrichCamel yeah, I initially thought that way too but the thing that confuses me the most is when the question says write it in the follow representation, |0⟩↔(1 0 0)^T , |1⟩↔(0 1 0)^T and |2⟩↔(0 0 1)^T, it just means we have to write the operator in 3x 3 matrix but not in 3x3 matrix and must be identity matrix right? | |
| Mar 22, 2018 at 19:28 | comment | added | ostrichCamel | @john, I don't know if you got the answer in the end, but it occurs to me that you might simply be confused by the notation. The matrix is called $T$. When they write the basis vectors for $\lvert 0 \rangle, \lvert 1 \rangle, \lvert 2 \rangle$, they use the letter $T$ again, but here it denotes " matrix transpose" -- it has nothing to do with the name of the matrix. If they had been able to typeset column vectors, those superscripts wouldn't be necessary. | |
| Mar 22, 2018 at 13:34 | history | edited | knzhou | CC BY-SA 3.0 |
added 10 characters in body; edited title
|
| Mar 22, 2018 at 10:20 | history | edited | Kyle Kanos | CC BY-SA 3.0 |
added 596 characters in body; edited tags
|
| Mar 22, 2018 at 10:20 | comment | added | Selene Routley | "Tritter" is a new word for me. I've never heard it: it makes me think at once of the short messaging service and a pig with a sore foot. I ken this kind of thing from 3x3, symmetric optical fiber directional couplers and indeed any physical device realizing this trotter operator has to have a threefold, cyclic physical symmetry, or at least simulate such. | |
| Mar 22, 2018 at 10:11 | answer | added | Selene Routley | timeline score: 1 | |
| S Mar 22, 2018 at 9:55 | history | suggested | Alex Robinson | CC BY-SA 3.0 |
improved word order
|
| Mar 22, 2018 at 9:16 | review | Suggested edits | |||
| S Mar 22, 2018 at 9:55 | |||||
| Mar 22, 2018 at 8:50 | answer | added | ostrichCamel | timeline score: 2 | |
| Mar 22, 2018 at 8:07 | review | First posts | |||
| Mar 22, 2018 at 9:16 | |||||
| Mar 22, 2018 at 8:05 | history | asked | john | CC BY-SA 3.0 |