Quantum Computation: Qbits

Quantum Computation: Qbits

A ‘bit’ is a fundamental concept in classical computing. The ‘quantum bit’ or qbit is it’s analog in quantum computation.

It is treated like an abstract mathematical object, which can be realized by physical systems. By treating qbits as an abtract entity we are able to build a theory of quantum computation without relying on a specific system.

Definition

A qbit is a mathematical object which has a state that is a linear combination of

0> and

1>

The state of a qbit can be represented as:

psy

= \alpha

0> + \beta

1>

where \alpha and \beta are complex numbers.

A classical bit can be in either 0 or 1, a qbit, however, can exist in a superposition of the two. Although, when we observe it, we see either 0, or 1, with a certain probability.