物理中，零点能量（可简称零点能）是量子力学所描述的物理系统会有的最低能量，此时系统所处的态称为基态；所有量子力学系统都有零点能量。这个辞汇起源于量子谐振子处在基态时，量子数为零的考量。

在量子场论中，这个辞汇和真空能量是等义词，指的空无一物的空间仍有此一定能量存在，对一些系统可以造成扰动，并且导致一些量子电动力学会出现的现象，例如兰姆位移与卡西米尔效应；它的效应可在纳米尺度的组件直接观测的到。

在宇宙论中，真空能量被视为宇宙常数的来源，和造就宇宙加速膨胀的暗能量相关。

因为零点能量是一系统可能持有的最低能量，因此此项能量是无法自系统移除。尽管如此，零点能量的概念以及自真空汲取「免费能量」的可能性引起业余发明者的注目——许多「永动机」或称「免费能量设备」等的提案都运用这项概念来解释，但科学界认为这些是不可能的。这项热潮以及相伴的趣味理论诠释促成了大众文化中「零点能量」概念的成长，常出现在科幻书刊、游戏、电影等处。

Zero-point energy, also called quantum vacuum zero-point energy, is the lowest possible energy that a quantum mechanical physical system may have; it is the energy of its ground state.

All quantum mechanical systems undergo fluctuations even in their ground state and have an associated zero-point energy, a consequence of their wave-like nature. The uncertainty principle requires every physical system to have a zero-point energy greater than the minimum of its classical potential well. This results in motion even at absolute zero. For example, liquid helium does not freeze under atmospheric pressure at any temperature because of its zero-point energy.