I remembered reading something about this before, and I've managed to tracke down this document
that someone posted in response to a previous thread
. It is a handbook for new students at ETH, a university in Zurich. Your question is answered on pages 59-60. Sorry to give you bad news, but it does not look very promising for spouses of students to get a work permit:
"You have no right to bring your family with you. However if your revenue is high enough and you have at least a two room apartment, you can get permission to bring your spouse or children with you. However they are not allowed to work in Switzerland. If you have a child during the course of your Ph.D. you might have difficulties getting a residence permit for the baby."