Reference to array element

Is it possible to have a reference to an array element? I've tried this with no luck:

$array[0] = 'a';
$ref &= $array[0];
echo $ref; //output: 
$ref = 'b';
echo $ref; //output: b
echo $array[0]; //output: a

Code (markup):

What am I missing here?

 

The & should go behind the equal sign.

 

Oh you're right! Thanks, didn't spot that. You'd think they'd be consistent with all their other *= operators but oh well...