**Quantum computing**

is the area of study focused on developing computer technology based on

the principles of quantum theory. The quantum computer, following the

laws of quantum physics, would gain enormous processing power through

the ability to be in multiple states, and to perform tasks using all

possible permutations simultaneously.

**A Comparison of Classical and Quantum Computing**

Classical computing relies, at its ultimate level, on principles expressed by

Boolean algebra. Data must be processed in an exclusive binary state at

any point in time or bits. While the time that each transistor or

capacitor need be either in 0 or 1 before switching states is now

measurable in billionths of a second, there is still a limit as to how

quickly these devices can be made to switch state. As we progress to

smaller and faster circuits, we begin to reach the physical limits of

materials and the threshold for classical laws of physics to apply.

Beyond this, the quantum world takes over. In a quantum computer, a

number of elemental particles such as electrons or photons can be used

with either their

Boolean algebra. Data must be processed in an exclusive binary state at

any point in time or bits. While the time that each transistor or

capacitor need be either in 0 or 1 before switching states is now

measurable in billionths of a second, there is still a limit as to how

quickly these devices can be made to switch state. As we progress to

smaller and faster circuits, we begin to reach the physical limits of

materials and the threshold for classical laws of physics to apply.

Beyond this, the quantum world takes over. In a quantum computer, a

number of elemental particles such as electrons or photons can be used

with either their

*charge*or*polarization*acting as a representation of 0 and/or 1. Each of these particles is known as a quantum bit, or*qubit*, the nature and behavior of these particles form the basis of quantum computing.**Quantum Superposition and Entanglement**

The two most relevant aspects of quantum physics are the principles of

*superposition*and*entanglement*.*Superposition*:

Think of a qubit as an electron in a magnetic field. The electron’s

spin may be either in alignment with the field, which is known as a

spin-up state, or opposite to the field, which is known as a spin-down

state. According to quantum law, the particle enters a superposition of

states, in which it behaves as if it were in both states simultaneously.

Each qubit utilized could take a superposition of both 0 and 1.

*Entanglement:*

Particles that have interacted at some point retain a type of

connection and can be entangled with each other in pairs, in a process

known as

*correlation*. Knowing the spin state of one

entangled particle — up or down — allows one to know that the spin of

its mate is in the opposite direction. Quantum entanglement allows

qubits that are separated by incredible distances to interact with each

other instantaneously (not limited to the speed of light). No matter how

great the distance between the correlated particles, they will remain

entangled as long as they are isolated. Taken together, quantum

superposition and entanglement create an enormously enhanced computing power.

Where a 2-bit register in an ordinary computer can store only one

of four binary configurations (00, 01, 10, or 11) at any given time, a

2-qubit register in a quantum computer can store all four numbers

simultaneously, because each qubit represents two values. If more qubits

are added, the increased capacity is expanded exponentially.

of four binary configurations (00, 01, 10, or 11) at any given time, a

2-qubit register in a quantum computer can store all four numbers

simultaneously, because each qubit represents two values. If more qubits

are added, the increased capacity is expanded exponentially.

**Difficulties with Quantum Computers**

**Interference**

— During the computation phase of a quantum calculation, the slightest

disturbance in a quantum system (say a stray photon or wave of EM

radiation) causes the quantum computation to collapse, a process known

as

*de-coherence*. A quantum computer must be totally isolated from all external interference during the computation phase.

**Error correction**

— Given the nature of quantum computing, error correction is ultra

critical — even a single error in a calculation can cause the validity

of the entire computation to collapse.

**Output observance**— Closely related to the above two, retrieving output data after a quantum calculation is complete risks corrupting the data.

**The Future of Quantum Computing**

The biggest and most important one is the ability to factorize a very large

number into two prime numbers. That’s really important because that’s

what almost all

use and can be de-encrypted. A quantum computer should be able to do

that relatively quickly. Calculating the positions of individual atoms

in very large molecules like polymers and in viruses. The way that the

particles interact with each other — if you have a quantum computer you

could use it to develop drugs and understand how molecules work a bit

better.

number into two prime numbers. That’s really important because that’s

what almost all

*encryption*of internet applicationsuse and can be de-encrypted. A quantum computer should be able to do

that relatively quickly. Calculating the positions of individual atoms

in very large molecules like polymers and in viruses. The way that the

particles interact with each other — if you have a quantum computer you

could use it to develop drugs and understand how molecules work a bit

better.

Even though there are many problems to overcome, the breakthroughs in the last 15 years, and especially in the last 3, have made some form of

practical quantum computing possible. However, the potential that this

technology offers is attracting tremendous interest from both the

government and the private sector. It is this potential that is rapidly

breaking down the barriers to this technology, but whether all barriers

can be broken, and when, is very much an open question.

practical quantum computing possible. However, the potential that this

technology offers is attracting tremendous interest from both the

government and the private sector. It is this potential that is rapidly

breaking down the barriers to this technology, but whether all barriers

can be broken, and when, is very much an open question.

**Ahmed Banafa**, Author the Books :

Read more articles at Technology Trends by Prof. Ahmed Banafa

**References**

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