Quantum Computer vs. Classical Computer

Quantum computers have a more basic structure than classical computers. They have no memory or processor. All a quantum computer uses is a set of superconducting qubits.

Quantum computers and classical computers process information differently. A quantum computer uses qubits to run multidimensional quantum algorithms. Their processing power increases exponentially as qubits are added. A classical processor uses bits to operate various programs. Their power increases linearly as more bits are added. Classical computers have much less computing power.

Classical computers are best for everyday tasks and have low error rates. Quantum computers are ideal for a higher level of task, e.g., running simulations, analyzing data (such as for chemical or drug trials), creating energy-efficient batteries. They can also have high error rates.

Classical computers don't need extra-special care. They may use a basic internal fan to keep from overheating. Quantum processors need to be protected from the slightest vibrations and must be kept extremely cold. Super-cooled superfluids must be used for that purpose.

Quantum computers are more expensive and difficult to build than classical computers.

Classical computing relies on principles expressed by Boolean algebra, usually operating on a logic gate principle. Data must be processed in an exclusive binary state at any point in time -- either 0 for off or 1 for on. These values are bits. The millions of transistors and capacitors at the heart of computers can only be in one state at any point. There's also still a limit as to how quickly these devices can be made to switch states.

By comparison, quantum computers operate with a two-mode logic gate -- XOR and a mode called QO1-- which lets them change 0 into a superposition of 0 and 1. In a quantum computer, particles such as electrons or photons can be used. Each particle is given a charge, or polarization, acting as a representation of 0 and 1. Each particle is referred to as a quantum bit, or qubit. The nature and behavior of these particles form the basis of quantum computing and quantum supremacy.