Conventional Computing vs Quantum Computing
Last Updated : 06 May, 2023
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 |
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| 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. |
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| 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. |
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| The circuit behavior is governed by classical physics. | The circuit behavior is governed by quantum physics or quantum mechanics. |
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| 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. |
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| 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. |
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| 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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| Feature | Conventional Computing | Quantum Computing |
| Basic Unit | Bit | Qubit |
| State | Either 0 or 1 | Can be in multiple states simultaneously due to superposition |
| Logical Operations | Boolean Logic (AND, OR, NOT) | Quantum Gates (Hadamard, CNOT, etc.) |
| Speed | Limited by classical physics | Can perform certain calculations much faster than classical computers |
| Memory | Stored in binary digits | Stored in qubits |
| Entanglement | Not possible | Allows two or more qubits to be correlated |
| Error sensitivity | Not as sensitive | Extremely sensitive to noise and errors |
| Applications | Software, gaming, simulations, etc. | Cryptography, chemistry, machine learning, etc. |
Advantages of Conventional Computing:
Well-established: Conventional computing is well-established and widely used in many applications.
Cost-effective: Conventional computing is cost-effective and accessible to many users, as it does not require specialized hardware.
Fast for certain types of problems: Conventional computing is fast and efficient for problems that can be easily broken down into sequential steps and for problems that do not involve large numbers of variables.
Deterministic: Conventional computing is deterministic, meaning that given the same inputs, the output is always the same.
Disadvantages of Conventional Computing:
Limited parallel processing: Conventional computing can perform limited parallel processing, which can limit its performance for certain types of problems.
Inefficient for certain types of problems: Conventional computing can be inefficient for certain types of problems that involve large numbers of variables or complex relationships.
Limited by classical physics: Conventional computing is limited by classical physics, which can make certain types of problems impossible to solve or prohibitively difficult.
Advantages of Quantum Computing:
Massive parallel processing: Quantum computing can perform massive parallel processing, which can enable faster solutions for certain types of problems.
Efficient for certain types of problems: Quantum computing is efficient for certain types of problems that involve large numbers of variables or complex relationships.
Non-deterministic: Quantum computing is non-deterministic, which can enable the exploration of many potential solutions simultaneously.
Disadvantages of Quantum Computing:
Specialized hardware: Quantum computing requires specialized hardware, including cryogenic equipment to maintain the qubits at low temperatures and specialized control electronics to manipulate the qubits.
Expensive: Quantum computing is expensive, as it requires specialized hardware and expertise.
Limited applicability: Quantum computing is highly specialized and is suited for certain types of problems, making it less applicable for many applications.
Fragile: Quantum computing is fragile and sensitive to external disturbances, which can cause errors in computations.