离子阱，又称离子陷阱，是一种利用电场或磁场将离子（即带电原子或分子）俘获和囚禁在一定范围内的装置，离子的囚禁在真空中实现，离子与装置表面不接触。应用最多的离子阱有“保罗阱”（四极离子阱，沃尔夫冈·保罗）和彭宁离子阱。

离子阱可以应用于实现量子计算机。传统计算机以电位的高低表示比特0和1，而量子计算机以粒子的量子力学状态，如原子的自旋方向等表示0和1，称为“量子比特”。离子阱利用电极产生电场，将经过超冷处理的离子囚禁在电场里，实现量子比特。

An ion trap is a combination of electric or magnetic fields used to capture charged particles, often in a system isolated from an external environment. Ion traps have a number of scientific uses such as mass spectrometry, basic physics research, and controlling quantum states. The two most common types of ion trap are the Penning trap, which forms a potential via a combination of electric and magnetic fields, and the Paul trap which forms a potential via a combination of static and oscillating electric fields.