Edit in JSFiddle

<div ng-controller="MainCtrl">
  MainCtrl:
  <input type="text" ng-model="user.name">
</div>
<div ng-controller="SecondCtrl">
  SecondCtrl:
  <input type="text" ng-model="user.name">
</div>

var app = angular.module('app', []);

app.controller('MainCtrl', function($scope, UserInformation) {
  $scope.user = UserInformation;
});

app.controller('SecondCtrl', function($scope, UserInformation) {
  $scope.user = UserInformation;
});

app.factory('UserInformation', function() {
  var user = {
    name: "Angular.js"
  };

  return user;
});