Anti aliasing from latex to pdf

There are no "official" outline fonts for TeXs native Computer Modern Roman fonts in T1 (also called EC) encoding.

For the old OT1 encoding there are the Blue Sky fonts, a free set of Type1 fonts which were hand-outlined. You'll see these in the log as follows if you leave out \usepackage[T1]{fontenc}:

</usr/local/texlive/2011/texmf-dist/fonts/type1/public/amsfonts/cm/cmr10.pfb>

For EC encoding there are for instance the CM Super fonts, which are also outline fonts, but they are autotraced and the package is huge, so they seem to be missing on some systems. They seem to be included in a full TeXLive install nowadays, so with \usepackage[T1]{fontenc} I get:

</usr/local/texlive/2011/texmf-dist/fonts/type1/public/cm-super/sfrm1000.pfb>

If you don't have the cm-super package installed, you'll get bitmap fonts generated from the original Metafont sources of the EC fonts, which gives the pixelated effect you are seeing.

Another alternative for T1 encoding is to load the Latin Modern fonts with

\usepackage{lmodern}

as mentioned in the comment by matth. They are a hand-outlined replacement for Computer Modern, but they look different from the EC fonts in some places.

Adding \usepackage[T1]{fontenc} to your preamble is a good thing, but sadly it will load a bitmap font by default. So in order to hace a nice looking font, you need to load one. Adding microtype makes the type face even nicer. Here is an example of what I put in my preamble:

\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage{lmodern}
\usepackage[T1]{fontenc}
\usepackage[babel=true]{microtype}