how to send multiple data with $.ajax() jquery

i am trying to send multiple data using j query $.ajax method to my php script but i can pass only single data when i concatenate multiple data i get undefined index error in my php script tat means the ajax request is made but data is not sent i need to know how should i format multiple data to successively send it to processing script in name vale pair here is what i have written

<script>
  $(document).ready(function() {

    $('#add').click(function () {

      var name = $('#add').attr("data_id");

      var id = $('#add').attr("uid");

      var data = 'id='+ id  & 'name='+ name; // this where i add multiple data using  ' & '

      $.ajax({
        type:"GET",
        cache:false,
        url:"welcome.php",
        data:data,    // multiple data sent using ajax
        success: function (html) {

          $('#add').val('data sent sent');
          $('#msg').html(html);
        }
      });
      return false;
    });
  });
</script>



<span>
  <input type="button" class="gray_button" value="send data" id="add" data_id="1234" uid="4567" />
</span>
<span id="msg"></span>