Friends welcome to my youtube channel Dhanesh here
In this video.  I am going to give you an introduction to quantum computing
let's start. Quantum computing began in the early 1980s
When physicist Paul A Benioff proposed a quantum mechanical model of the Turing machine?
Richard Feynman and Yuri
Manin
Later suggested that a quantum computer had the potential
to simulate
Things that a classical computer could not .
In 1994 Peter Shor developed a Quantum algorithm for factoring integers,
That had the potential to decrypt RSA encrypted communications
Next we will discuss what is quantum computing?
Quantum computing is the use of quantum mechanical
phenomenon such as
superposition
and entanglement to perform
computation.  Computers that perform quantum computations are known as quantum computers.
Next thing we need to understand is Qubit.
The basis of quantum computing is the qubit.
Unlike a normal computer bit,
which can be 0 or 1, a qubit can be either of those,
or a
superposition of both 0 and 1.
Superposition and entanglement are two features of quantum physics on which of these supercomputers are based.
This empowers quantum computers
to handle operations at speeds
exponentially higher than conventional computers and at much lesser energy consumption.
Next we will discuss in detail about superposition.
Superposition refers to the quantum phenomenon
where a quantum system can exist in multiple states,
or places
at the exact same time. In other words something can be here and
there or up and down at the same time.
Quantum superposition is a fundamental principle of quantum mechanics.
It states that, much like waves in  classical physics,
any two
quantum states can be added together and the result will be another valid quantum state and conversely,
that every quantum state can be represented as a sum of two or more other distinct states.
Schrodinger's cat is a thought experiment,
sometimes described as a paradox, devised by Austrian physicist Erwin Schrodinger in 1935,
during the course of discussion with Albert Einstein.
in Schrodinger's imaginary
experiment,
you place a cat in a box with a tiny bit of radioactive substance.
When the radioactive substance decays it triggers a
 
Geiger counter which causes a poison or explosion to be released
that kills the cat .The cat ends up both dead and alive at the same time.
Because the existence of a cat that is both dead and alive at the same time is absurd
and does not happen in the real world, this thought experiment shows that wave function collapses
are not just driven by conscious observers.
Next phenomenon we need to understand is quantum entanglement.
Quantum entanglement is the name given to a special connection between pairs or groups of quantum systems
or any objects described
 
 
described by quantum mechanics.
Quantum entanglement is one of the biggest parts of quantum mechanics,
that makes it hard to understand in terms of
everyday world.
particles of light
or photons can be entangled
by splitting single particle into two photons in a
laser arrangement
with a special crystal.
Researchers can generate pairs of qubits that are entangled,
which means the two members of a pair excess in a single quantum state.
Changing the state of one of the qubits will instantaneously
Change the state of the other one in a predictable way.
See next we will discuss where quantum computers are used?
Quantum computers are used in
optimization problems ,chemistry, artificial intelligence ,data security etc
In a complex data set,
Ieature selection
involves an exhaustive research.
whose complexity
often reaches exponential, making it impractical to undertake any such effort.
The users end up using heuristic methods
with polynomial time complexity.
However quantum computers can accomplish such optimization with
polynomial time complexity,
using parallel computation
and without having a need for imperfect heuristic
optimization methods.
Even optimization is needed in speech recognition, image recognition.
Here also, we can use quantum computers.
And in biology finding the equilibrium configuration of  proteins we need to use optimization.
 
Quantum computing
And in machine learning we compute the cost function by summing over the square of the difference
of the observed and the expected values for the entire set,
to arrive at a cost or loss values for each training
data set
ran against the model.
 
 
 
 
For non-convex functions quantum computers are the solution for optimization problems.
Quantum computing we use in chemistry as well . By manipulating quantum states of matter and taking
Advantage of their unique features such as superposition
and entanglement ,quantum computers
promise to efficiently
deliver accurate results for many important problems in quantum chemistry ,such as the electronic structure of molecules.
Next is  quantum artificial intelligence.
Quantum artificial intelligence is an
interdisciplinary field that focus on building quantum algorithms for improving computational tasks
within artificial intelligence,
including
sub fields like machine learning .The entire concept of quantum enhanced
AI algorithms is still in conceptual
research domain.
Once a stable quantum computer gets evolved,
expect that machine learning will exponentially
accelerate even reducing the time to solve a problem
from hundreds of thousands of years to seconds.
Data security
This is another important area where  quantum computing can be used.
Virtually unbreakable
encryption?
Quantum computers will change the landscape of data security.
Even though quantum computers would be able to crack many of today's
encryption techniques ,predictions  are that they would create
hack proof replacements.
Uh
Next is
what we are going to discuss , is quantum computers a replacement for  classical computers ?
classical computers are better at
some tasks
than quantum computers.
For example email ,spreadsheets, and
desktop publishing to name a few.
The intent of conduct computers
Is to be a different tool to solve different problems,
not to replace classical computers.
Google, announced it has a quantum computer that is 100 million times
faster than any classical computer in its lab.
As you try out possible outcomes the complexity grows exponentially.
One thing that we do know about the nature of quantum computing is that algorithms that normally have exponentially
evolving complexity only have linear growth in complexity, when you viewed in the eyes of a quantum computer.
Quantum supremacy
In october 2019
Google, announced that its quantum computer had done
a computation in just
200 seconds,
which it claimed that the world's fastest
traditional
supercomputer would have needed
10 000 years to solve.
This means that it had reaches a milestone called
quantum supremacy, even though a few days later, its rival IBM
proved that it would it could have been done in hours
with a modern supercomputer,
which which would make the quantum computer only thousand times faster. In either case,
we now know that quantum computing actually works
and it is blistering fast.
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