Superposition is a fundamental principle in quantum mechanics that describes the ability of quantum systems to exist in multiple states simultaneously until they are measured. In other words, a quantum system can be in a combination, or superposition, of different states at the same time. This concept contrasts with classical physics, where an object typically exists in one definite state at any given time.
Mathematically, superposition is represented using wave functions, which describe the probabilities of finding a particle in various states when measured. When a measurement is made, the superposition collapses, and the system is observed to be in one of its possible states, with the probability of each outcome determined by the square of the magnitude of the corresponding coefficient in the superposition.
Superposition is a key aspect of quantum computing and quantum cryptography, where quantum bits (qubits) can represent multiple states simultaneously, potentially enabling computational and cryptographic capabilities beyond what is achievable with classical systems.