Definition

classical computing

Classical computing is another name for binary computing. In this traditional approach to computing, information is stored in bits that are represented logically by either a 0 (off) or a 1 (on). Today's processors, including X86 and ARM processors, support classical computing. 

Classical computing contrasts with quantum computing, a type of non-classical computing that represents data in quantum bits (qubits). A classical bit is either on or off, but a qubit can be on and off at the same time, a condition known as superposition.  

Unlike classical computers, quantum computers require specialized and expensive infrastructure. They must operate at near-absolute zero temperatures and be shielded from outside radio waves, light and magnetic fields to prevent errors.

Classical Computing

Quantum Computing

Used by large scale multi-purpose computers and devices.

Used by high speed, quantum mechanics based computers.

Information is stored in bits.

Information is stored in quantum bits.

There are a discrete number of possible states, 0 or 1.

There are an infinite, continuous number of possible states.

Calculations are deterministic, meaning repeating the same input results in the same output.

Calculations are probabilistic, meaning there are multiple possible outputs to the same input.

Data processing is carried out by logic and in sequential order.

Data processing is carried out by Quantum logic at parallel instances.

Operations are defined by Boolean Algebra.

Operations are defined by linear algebra over Hilbert space.

Circuit behavior is defined by classical physics.

Circuit behavior is defined by quantum mechanics.

This was last updated in November 2018

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