# What does |0> mean? ie what does the | > mean/do?

What does |0> mean? ie what does the | > mean/do?

Hurkyl
Staff Emeritus
Gold Member
| > is just a decoration; it makes something look different. It's no different than when you put a little arrow over your vectors, or little hats over your unit vectors.

Ah, right. I thought it was maybe linked to < > meaning expectation value.

Staff Emeritus
Gold Member
Dearly Missed
Ah, right. I thought it was maybe linked to < > meaning expectation value.

Well when you take the inner product of <x| with |x> you get <x|x>, which is a number and can be thought of as an expecttion. So the notation ("Bra and ket") isn't entirely arbitrary.

dextercioby
$|0\rangle$ stands for the ground state for a quantum system (the state with the minimum possible energy). The $|\rangle$ with "something" in between the vertical line and the angle means that the "something" is a "ket" vector.