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

1. Nov 26, 2006

### Lee

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

2. Nov 26, 2006

### Hurkyl

Staff Emeritus
| > 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.

3. Nov 26, 2006

### Lee

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

4. Nov 26, 2006

Staff Emeritus
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.

5. Nov 27, 2006

### 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.

Daniel.