Lieb-Liniger model of a Bose Gas

Apparatus and methods for providing granular material to a loading hopper preparatory to processing, provide an at least partially transparent receptacle for receiving material prior to processing machinery supplied by the hopper with the receptacle having a top, a valve for selectably connecting the receptacle to vacuum or to ambient air, vacuum drawn in the receptacle, a conduit connecting the receptacle to a supply of granular material, a valve selectably permitting material flow from the receptacle into the hopper and control temporally adjustably closing the first valve and opening the second valve responsively to visually detected presence of a suitable amount of material in the receptacle.