Ember service property with promise data

I have a service to get the current user and it returns correctly when I return a hardcoded object, but I can't get it to return data from an ajax call.

export default  Ember.Service.extend({
  currentUser: Ember.computed(function() {
    Ember.$.ajax({
      url: "http://localhost:8000/v1/me/"
    }).then(function(data){
      console.log(data);
      return data;
    },
    function(err){
      console.log(err);
    });
  }),
});

I know the data is being returned correctly, according to the console.log in the promise.

When I use this service in a controller, it is returning nothing for the currentUser, however I know everything is hooked up correctly because if i substitute an Ember.Object in for the ajax query, it returns that object to the Controller.

Do I need to do something special with the property that contains the ajax query to be able to use the returned data in a controller?