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Difference between Bits and Quantum Bits

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1. Bits : 
It’s a single unit of information that has a value of either 0 or 1 (off or on, false or true, low or high). 

2. Quantum Bits : 
In quantum computing, a qubit or quantum bit is the basic unit of quantum information—the quantum version of the classical binary bit physically realized with a two-state device. A qubit is a two-state quantum-mechanical system, one of the simplest quantum systems displaying the peculiarity of quantum mechanics. 

Difference between Bits and Qubits in Quantum Computing : 

1. The device computes by manipulating those bits with the help of logical gates (AND, OR, NOT). The device computes by manipulating those bits with the help of quantum logic gates.
2. A classical computer has a memory made up of bits where each bit hold either a one or zero. A qubits (quantum bits) can hold a one, a zero or crucially a superposition of these.
3. Bits are used in classical computers. Qubits(Quantum bits) are use in quantum computer
4. Information is stored in bits, which take the discrete values 0 and 1. Information is stored in quantum bits, or qbits. A qbit can be in states labelled |0} and |1}, but it can also be in a superposition of these states, a|0} + b|1}, where a and b are complex numbers. If we think of the state of a qbit as a vector, then superposition of states is just vector addition.
5. For example, if storing one number takes 64 bits, then storing N numbers takes N times 64 bits. For example, for every extra qbit you get, you can store twice as many numbers. For example, with 3 qbits, you get coefficients for |000}, |001}, |010}, |011}, |100}, |101}, |110} and |111}.
6. Bits are slow. Qubits are faster.
7. Its circuit behaviour based on classical physics. Its circuit behaviour based on quantum mechanics.


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Last Updated : 31 May, 2021
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