Provided that your server receives data in the form of a string which it should if you’re using the jQuery serialize() function.
It will be something like:
name1=value&name2=value&name3=value
You just need to parse the string into an array as follows:
$parameters = array();
parse_str($_GET, $parameters);
See the following for more information: http://www.php.net/manual/en/function.parse-str.php