The qbit: The next iteration of bit

The qbit: The next iteration of bit

Well if you live on the planet Earth, not on the Mars…..haa…haa…., then you must know or at least heard about bits? Don’t you…? A bit is the smallest unit of data information in computers that can have a value of either 0 or 1 (off or on, false or true, low or high). But the qbit is different from the bit and has many advantages over bits. In this post, you will find the differences and advantages of qbit over the bit. So without any further ado. let’s get started.

What is Bit (Binary digit)?

A bit (binary digit) is the smallest unit of data in the form of information in a computer. A nibble comes after a bit, although nibble has been skipped and a byte comes after a bit. A bit has a single binary value, either 0 or 1. Although computers are generally designed to store data and execute instructions in bit multiples called bytes. In most computer systems, there are eight bits in a byte. The value of a bit is usually stored as either above or below a designated level of electrical charge in a single capacitor within a memory device.

Binary digit

An overlook on other higher units of bit

  • 4 bits in a Nibble (N)
  • 8 bits in a Byte (B)
  • 8000 bits in a Kilobyte (KB)
  • 8,000,000 bits in a Megabyte (MB)
  • 8,000,000,000 bits in a Gigabyte (GB)
  • 8,000,000,000,000 bits in a Terabyte (TB)
  • 8,000,000,000,000,000 bits in a Petabyte (PB)
  • 8,000,000,000,000,000,000 bits in an Exabyte (EB)
  • 8,000,000,000,000,000,000,000 bits in a Zettabyte (ZB)
  • 8,000,000,000,000,000,000,000,000 bits in a Yottabyte (YB)

What is qbit?

In quantum computing, a qubit (qbit 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 (or two-level) quantum-mechanical system, one of the simplest quantum systems displaying the weirdness of quantum mechanics.

Quantum bit

Example: The spin of the electron in which the two levels can be taken as spin up and spin down; or the polarization of a single photon in which the two states can be taken to be the vertical polarization and the horizontal polarization.

In a classical system, a bit would have to be in one state or the other. However, quantum mechanics allows the qbit to be in a coherent superposition of both states/levels at the same time, a property that is fundamental to quantum mechanics and thus quantum computing.

Bit versus qbit

There are two possible outcomes for the measurement of a qbit – usually taken to have the value “0” and “1”, like a bit or binary digit, characterized as 0 and 1, is used to represent information in classical computers. However, whereas the state of a bit can only be either 0 or 1.

But the general state of a qubit according to quantum mechanics can be a coherent superposition of both. Moreover, whereas a measurement of a classical bit would not disturb its state, a measurement of a qubit would destroy its coherence and irrevocably disturb the superposition state.

Quantum bit v/s binary bit

It is possible to fully encode one bit in one qubit. However, a qubit can hold more information. For a system of n components, a complete description of its state in classical physics requires only n bits, whereas in quantum physics it requires (2n−1) complex numbers.


  • In Quantum computers

A quantum computer is a device that performs quantum computing. Such a computer is different from binary digital electronic computers based on transistors. Whereas common digital computing requires that the data be encoded into binary digits (bits), each of which is always in one of two definite states (0 or 1).

Quantum computation uses quantum bits or qubits, which can be in superpositions of states. A quantum Turing machine is a theoretical model of such a computer and is also known as the universal quantum computer.

Quantum computers

As of 2018, the development of actual quantum computers is still in its early stage, but experiments have been carried out in which quantum computational operations were executed on a very small number of quantum bits.

A small 20 – qbit quantum computer exists and is available for experiments via the IBM quantum experience project. D-Wave Systems has been developing their own version of a quantum computer that uses annealing.

Quantum processor chip
  • In researches

Both practical and theoretical research continues, and many national governments and military agencies are funding quantum computing research in additional effort to develop quantum computers for civilian, business, trade, environmental and national security purposes, such as cryptanalysis.

Quantum entanglement also allows multiple states to be acted on simultaneously, unlike classical bits that can only have one value at a time. Entanglement is a necessary ingredient of any quantum computation that cannot be done efficiently on a classical computer.

Binary bit state

Large-scale quantum computers would theoretically be able to solve certain problems much more quickly than any classical computers that use even the best currently known algorithms.

Note: The Bell state forms part of the setup of the superdense coding, quantum teleportation, and entangled quantum cryptography algorithms.

A major hurdle facing quantum computing as of 2018 is the noise in quantum gates that limit the size of quantum circuits that can be executed reliably.

So that’s it for today guys. Did you enjoy reading this article? If so, then please share it. If you have any suggestions and queries related to the post, let me know in the comment section below. Please do like and share this post to your circle to explore the knowledge you must know.

Thank you.

Anil Kashyap

I want to explore new things every single moment of life. Life motto: Learn and teach as much as you can until your last breath.

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