We’ve been using computers since early 19th century. We’re currently in the fourth generation of computers with the microprocessors after vacuum tubes, transistors and integrated circuits. They were all based on conventional computing which is based on the classical phenomenon of electrical circuits being in a single state at a given time, either on or off.
The fifth generation of computers is currently under development of which quantum computing or quantum computers being most popular. Quantum computers are totally different from conventional computers on how they work. Quantum computers are based on the phenomenon of Quantum Mechanics, the phenomenon where it is possible to be in more than one state at a time.
Difference between conventional computing and quantum computing:
|Conventional Computing||Quantum Computing|
|Conventional computing is based on the classical phenomenon of electrical circuits being in a single state at a given time, either on or off.||Quantum computing is based on the phenomenon of Quantum Mechanics, such as superposition and entanglement, the phenomenon where it is possible to be in more than one state at a time.|
|Information storage and manipulation is based on “bit”, which is based on voltage or charge; low is 0 and high is 1.||Information storage and manipulation is based on Quantum Bit or “qubit”, which is based on the spin of electron or polarization of a single photon.|
|The circuit behavior is governed by classical physics.||The circuit behavior is governed by quantum physics or quantum mechanics.|
|Conventional computing use binary codes i.e. bits 0 or 1 to represent information.||Quantum computing use Qubits i.e. 0, 1 and superposition state of both 0 and 1 to represent information.|
|CMOS transistors are the basic building blocks of conventional computers.||Superconducting Quantum Interference Device or SQUID or Quantum Transistors are the basic building blocks of quantum computers.|
|In conventional computers, data processing is done in Central Processing Unit or CPU, which consists of Arithmetic and Logic Unit (ALU), processor registers and a control unit.||In quantum computers, data processing is done in Quantum Processing Unit or QPU, which consists of a number of interconnected qubits.|
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