First and foremost what is a quantum computer Now a days why most of the tech gaints are such as Google , Amazon, ibm, facebook are using them Quantum computing harnesses the phenomena of quantum mechanics to deliver a huge leap forward in computation to solve certain problems When it comes to a Classical computers manipulate ones and zeroes to crunch through operations, but quantum computers use quantum bits or qubits.

Just like classical computers, quantum computers use ones and zeros, but qubits have a third state called “superposition” that allows them to represent a one or a zero at the same time. Do we actually need quantum computer For some problems, supercomputers aren’t that super Until now, we’ve relied on supercomputers to solve most problems. These are very large classical computers, often with thousands of classical CPU and GPU cores. However, supercomputers aren’t very good at solving certain types of problems, which seem easy at first glance. This is why we need quantum computers.

## Why quantum computers are faster?

Quantum computers can create vast multidimensional spaces in which to represent these very large problems. Classical supercomputers cannot do this. Algorithms that employ quantum wave interference are then used to find solutions in this space, and translate them back into forms we can use and understand.

Here’s why it matters

One promising quantum algorithm that uses these techniques is called Grover's Search. Suppose you need to find one item from a list of N items. On a classical computer you'd have to check N/2 items on average, and in the worst case you would need to check all N. Using Grover's search on a quantum computer you would find the item after checking roughly √N of them. This represents a remarkable increase in processing efficiency and time saved. For example, if you wanted to find one item in a list of 1 trillion, and each item took 1 microsecond to check:

Classical computer
About 1 *week*
Quantum computer
About 1 *second*

## How quantum computers work ?

You don't have to know how quantum computers work to use them, however the science is interesting because it represents so many advanced fields coming together.

Given the potential computational power of quantum computers, you might expect them to be gigantic. In fact they are currently about the size of a domestic fridge, with an accompanying wardrobe-sized box of control electronics.

In the same way that bits are used in a classical computer, at the heart of the quantum computer are quantum bits or qubits (CUE-bits) which can store information in quantum form.

## Inside it consists of

### Superfluids

First we use superfluids to chill superconductors. We get these superconductors very cold – about a hundredth of a degree Celsius above absolute zero: the theoretically lowest temperature allowed by the laws of physics.

## Superconductors

When we put electrons through superconductors they pair up into something called Cooperpairs that quantum tunnel through something called a Josephson junction.

## Control

Essentially, this is a superconducting qubit. By firing photons at the qubit, we can control its behavior and get it to hold, change, and read out information.

## Superposition

A qubit itself isn’t very useful. However, by creating many and connecting them in a state called superposition we can create vast computational spaces. We then represent complex problems in this space using programmable gates.

## Entanglement

Quantum entanglement allows qubits, which behave randomly, to be perfectly correlated with each other. Using quantum algorithms that exploit quantum entanglement, specific complex problems can be solved more efficiently than on classical computers.

## Where are quantum computers used?

A new generation of electric vehicles through quantum battery technology

Reducing atmospheric carbon emissions using quantum computing aided material discovery

Searching for Higgs events and the origins of the universe

## Effects of quantum computers

**Quantum computers** are exceedingly difficult to engineer, build and program. As a result, they are crippled by errors in the form of noise, faults and loss of **quantum** coherence, which is crucial to their operation and yet falls apart before any nontrivial program has a chance to run to completion.

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