newcommand for ket-bra

macros

1,818

Solution 1

Use the braket package:

\documentclass{article}
\usepackage{braket}

\begin{document}

$\braket{\varphi|\psi}$

$\bra{\varphi}$

$\ket{\psi}$

$\ket{\varphi}\bra{\psi}$

\end{document}

Solution 2

try the command \ketbra{\phi}{\psi}, this should minimize the distance between the ket and the bra.

$command \ketbra{\phi}{\psi}$

1,818

Irreversible

Updated on July 09, 2020

Comments

Irreversible over 3 years
How can create a \newcommand that be able generate:
```
|\phi\rangle\langle \psi|
```
However \ket{\phi}\bra{\psi} does that but we think that the distance between ket and bra in |\phi\rangle\langle \psi| is shorter than that of \ket{\phi}\bra{\psi}.
- Troy almost 6 years
  
  \op{\phi}{\psi} from the physics package does this.
Mensch over 4 years

Welcome to TeX.SE! Can you please add a screenshot of your result? (And no, I did not downvote!)
Anti Earth over 3 years

This is actually the correct answer - use \ketbra from the physics package.
egreg over 3 years

@AntiEarth The physics package has several drawbacks.
orlp over 2 years

The spacing for the ketbra is too large.
egreg over 2 years

@orlp I believe this is a precise choice by the author of braket. Nothing prevents you from defining \newcommand{\ketbra}[2]{\mathinner{|{#1}\rangle\,\langle{#2}‌|}} that would use just one thin space in the middle instead of two.