▁location ▁L ▁send ▁classical ▁messages ▁and ▁quantum ▁states ▁towards ▁the ▁location ▁L . ▁If ▁the ▁pro ver ▁is ▁at ▁the ▁location ▁L ▁then ▁he ▁can ▁receive ▁the ▁signals ▁at ▁specific ▁times ▁and ▁reply ▁to ▁the ▁ver ifiers ▁with ▁requested ▁classical ▁messages ▁and / or ▁quantum ▁states , ▁which ▁must ▁be ▁received ▁by ▁the ▁ver ifiers ▁at ▁specific ▁times . ▁ ▁Quant um ▁location ▁authentication ▁was ▁first ▁investig ated ▁by ▁Kent ▁in ▁ 2 0 0 2 , ▁which ▁he ▁called ▁‘ quant um ▁tag ging ’ , ▁resulting ▁in ▁a ▁file d ▁US ▁pat ent ▁by ▁Kent ▁et . ▁al . ▁in ▁ 2 0 0 7 , ▁and ▁a ▁publication ▁in ▁the ▁academic ▁literature ▁in ▁ 2 0 1 0 , ▁after ▁a ▁paper ▁on ▁position - based ▁quantum ▁crypt ography ▁was ▁published ▁by ▁Bu hr man ▁et . ▁al . ▁There ▁is ▁a ▁no - go ▁theorem ▁for ▁quantum ▁location ▁authentication ▁proved ▁by ▁Bu hr man ▁et . ▁al . ▁stating ▁that ▁it ▁is ▁impossible ▁for ▁a ▁set ▁of ▁ver ifiers ▁to ▁authentic ate ▁the ▁location ▁of ▁a ▁pro ver ▁with ▁un cond itional ▁security . ▁This ▁is ▁because ▁for ▁any ▁quantum ▁location ▁authentication ▁protocol , ▁a ▁set ▁of ▁d ish on est ▁pro vers ▁sharing ▁a ▁sufficient ▁amount ▁of ▁ent ang lement ▁and ▁position ed ▁between ▁the ▁ver ifiers ▁and ▁the ▁location ▁L ▁can ▁intercept ▁all ▁communic ations ▁from ▁the ▁ver ifiers , ▁including ▁all ▁transm itted ▁quantum ▁states , ▁and ▁then ▁apply ▁a ▁non - local ▁quantum ▁operation ▁which