Second quantization
= Second quantization
{wiki=Second_quantization}
Second quantization is a formalism used in quantum mechanics and quantum field theory to describe and manipulate systems with varying particle numbers. It is particularly useful for dealing with many-body systems, where traditional first quantization methods become cumbersome. In the first quantization approach, particles are described by wave functions, and the focus is on the states of individual particles. However, this approach struggles to accommodate phenomena like particle creation and annihilation, which are crucial in fields like quantum field theory.