trit

A trit, short for ternary digit, is the basic unit of a ternary numeral system. It has three possible states, commonly labeled 0, 1, and 2, though some conventions use -1, 0, 1. As a generalization of the binary bit, a trit is the smallest unit of information in a ternary computer.

Ternary computing uses trits instead of bits. In theory a trit can store more information than a bit, since 2 possible states per bit vs 3 per trit; but physical realization is challenging. The information capacity of a trit is log2(3) bits ≈ 1.585 bits. The density can be advantageous, but error rates and circuit complexity offset benefits.

Historically, experimental ternary machines were built in the 1950s-1960s, notably the Setun computer in the Soviet Union. Modern mainstream architectures use binary logic, though ternary ideas remain of interest in research and certain niche applications.

In quantum information, a three-level quantum system is typically called a qutrit. The term trit is sometimes used in more informal discussions, but qutrit is the standard term in literature. Qutrits enable certain protocols and algorithms that differ from qubits.

See also qubit, qutrit, ternary logic, Setun.