Terminology » Other Wireless » Quantum Computer vs. Classical Computer: Key Differences

Quantum Computer vs. Classical Computer: Key Differences

quantum computing classical computing computer science technology quantum mechanics

This article compares quantum computers and classical computers, highlighting the fundamental differences between them.

Classical ComputerQuantum Computer
It is a large-scale integrated, multi-purpose computer.It is a high-speed parallel computer based on quantum mechanics.
Information storage is bit-based, relying on voltage or charge.Information storage is Quantum bit (Qubit) based on the direction of an electron spin.
Information processing is carried out by logic gates (e.g., NOT, AND, OR).Information processing is carried out by Quantum logic gates.
Circuit behavior is governed by classical physics.Circuit behavior is governed explicitly by quantum mechanics.
Classical computers use binary codes (bits 0 or 1) to represent information.Quantum computers use Qubits (i.e., 0, 1, and both simultaneously) to run machines faster.
Operations are defined by Boolean Algebra.Operations are defined by linear algebra over Hilbert Space and can be represented by unitary matrices with complex elements.
No restrictions exist on copying or measuring signals.Severe restrictions exist on copying and measuring signals.
Circuits are easily implemented in fast, scalable, and macroscopic technologies such as CMOS.Circuits must use microscopic technologies that are slow, fragile, and not yet scalable (e.g., NMR - Nuclear magnetic resonance).

In essence, classical computers store information as bits (0 or 1), while quantum computers use qubits. A qubit can be 0, 1, or a superposition of both, allowing for vastly more complex calculations. This is a crucial difference, as quantum computers leverage the principles of quantum mechanics to perform calculations that are impossible for classical computers.

The table above summarizes the main distinctions. For example, classical computers rely on Boolean algebra for operations, while quantum computers utilize linear algebra over Hilbert Space. Furthermore, quantum computers face significant limitations in copying and measuring signals, which are not present in classical systems.