如图，矩形$\mathit{ABCD}$中，$\mathit{AB}=2$，$E$为$\mathit{CD}$的中点，连接$\mathit{AE}$、$\mathit{BD}$交于点$P$，过点$P$作$\mathit{PQ}\perp \mathit{BC}$于点$Q$，则$\mathit{PQ}=$　 　．