Quantum computing seminar

Quantum Computing
Seminar Topic
Image of computer
The Next Generation of Computing Devices?

Outline :
 History of Computer .
 Why Quantum Computer ?
 How Quantum Computer works ?
 What can Quantum Computer do?
 Summary.
 What is Quantum Computer ?

History of Computer :
There are totally five Generations of Computer till now. Initially Generation term is
used to distinguish between varying hardware technology. But nowadays include
Hardware and Software.
Following are five main generation of computers :
S.N Generation Generation-period Description
1. First 1946-1959 Vacuum tube based
2. Second 1959-1965 Transistor based
3. Third 1965-1971 Integrated Circuit based
4. Fourth 1971-1980 VLSI microprocessor based
5. Fifth 1980-present ULSI microprocessor based

Computers Generation :
First Generation Second Generation

Computer Generation :
Third Generation
Fourth Generation
Fifth Generation

Quantum Computer :
A quantum computer is a machine that performs calculations based on the laws of
quantum mechanics, which is the behavior of particles at the sub-atomic level.

Classical Computer :
A computer that uses voltages flowing through circuits and gates, which use principle
of Digital electronics to perform operation .

Nobel Prize in Quantum Computing
Serge HarocheDavid Jeffrey Wineland
David J Wineland And Serge Haroche were Awarded with the Nobel Prize for
their work regarding measurement and manipulation of individual Quantum
Systems in 2012 .

Moore’s Law to the Atomic-scale

Moore’s Law to the Atomic-scale
Intel founder image
Gordon Moore :
Co-founder of Intel
No of transistor double after
18 month or 2 year.

Classical bits :
In the classical computer every thing is decoded in binary number and these two
binary bits are called Classical bits. Classical computer use these bits as combination
and perform the desired result.
We know that a single chip made of large no of transistor and all this
transistor must work reliably so that our computer/mobile/machine(based on
binary bit) can work properly.
Transistor

Quantum bits :
Quantum Physics (Quantum theory) is fundamental branch of
Physics which describe physical phenomena at atomic or sub-atomic
scale. Quantum mechanics provides an extremely accurate description of the
behaviour of photons , electrons and other atomic and molecular-scale objects or
sometime it is called reality.
Schrodinger Cat Experiment
Quantum Physics

Essential Elements of Quantum Physics
Particles are waves, and vice versa
Quantum physics tells us that every object in the universe has both particle like and wave-like
properties.
Quantum states are discrete
The “quantum” in quantum physics refers to the fact that everything in quantum physics comes
in discrete amounts.
 Well defined Spin
All the Quantum Element (electron, proton, neutron)have a well defined spin .Actually they have
momentum and Orientation in space.
Measurement determines reality
After a measurement is made, the state of the particle is absolutely determined.
Quantum physics is not magic
The bedrock principles of physics are still intact: energy is still conserved, entropy still increases,
nothing can move faster than the speed of light.

Quantum bits :
As we know that to perform operation we must need binary bits or something
equivalent to binary bits.
By using Q-bits we can do similar operation as classical computer.
Quantum computer use Quantum object to perform operation. We can either can
use a electron/proton as Q-bit. But it is very difficult to do operation with proton
because proton reside in nucleus. Electron of any material can be use as Q-bit .
Q-bit
Nucleus
p+

Quantum bits :
Digital information : 1

Quantum bits :
Digital information : 0
In this situation it can be either “0” or “1 ”. To predicate
this information we use Quantum formula that is :

Why Quantum Computer
Problem: A salesman has to travel to many cities and want to work out the shortest possible route.

Difficult problem : travelling salesman
Lets assume our classical computer speed
is 4.4 GHz ( intel i-7) (1010operation/sec )
Cities routes time taken
14 1011
10 sec
22 1019
771 year
28 1030 -------------
10 sec
771 year
Older than universe

How Quantum Computer works
A Quantum computer use the principle of Quantum physics. Like as classical
computer’s binary bits, in quantum Computer we use Q-bits. So now to understand
that how Quantum computer works we need to manipulate these Q-bits.
Quantum computers promise to do computation more powerfully than classical
computers due to the ability of a quantum computer to be in some states that have
no equivalence in a classical computer such as a superposition of values and/or an
entanglement between some particles of a quantum system.
Main building blocks of Quantum computer is :
 Q-bits
 Superposition
 Entanglement

Superposition
Superposition is a principle of Quantum physics that describe a challenging concept
about the nature and behaviour of matter at atomic level. Principle of super-
position states that while we don’t know what is the state of any Q-bit, actually it is
all the possible state simultaneously, as long as we don’t measure it.
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. Changing the
electron's spin from one state to another is achieved by using a pulse of energy,
such as from a laser.
But what if give half of the energy to total energy to change the spin of
electron ?

Superposition
By using this property we can do parallel processing , Classical computers today,
even so called parallel processors, truly they still do one task at a time. But their
time to do one task is so small that we can’t feel it and its seems as parallel
processing.
We can proof Superposition theorem with
Double slit Experiment
Schrodinger’s cat Experiment

Entanglement
Particles (such as photons, electrons, or q-bits) that have
interacted at some point retain a type of connection and can be entangled with
each other in pairs, in 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 and this is known as Entanglement.
Quantum entanglement allows qubits that are separated by
incredible distances to interact with each other instantaneously (not limited to the
speed of light). Taken together, quantum superposition and entanglement create an
enormously enhanced computing power.

Entanglement – spooky reaction
Spin up
Spin down
Spin down
Spin up
Entangle
particle
Entangle
particle

Power of Q-bits
No of Q-bits Classical possibilities power
0 or 1 2
00,01,10,11 4
000,001,010,011 8
100,101,110,111
N ---------------------- 2 𝑛
A 100 Q-bit quantum computer is more power full than a super computer….
A Quantum computer with 500 Q-bits is more power full than all the computer
of world connect together.

Representation of Q-bits/states
States can be represented via either the vector/matrix notation, or Dirac Notation.
Dirac Notation is more useful for describing the quantum states and the evolution of
the state of the system
Dirac notation :
1. |ψ> : denotes a column vector that represents a quantum state.
2. <ψ| : denotes a row vector that represents the dual of 1 , i.e. the complex conjugate transpose

Quantum Gates
2 × 2 unitary matrix for
Quantum Gates are same as classical Gates (AND,OR,NOT,XOR. etc.) but with a little
change that is we use Quantum vector/matrix instead of classical transistor.
although Quantum gates do the same functional operation.
Quantum gates used during the computation must follow the fundamental laws of
quantum physics. To satisfy this condition , using any matrix U as a quantum gate, it
must be unitary.
: U −1 = U † and UU † = I,

Quantum Architecture
Si surface
Magnet

What can Quantum Computer do ?
Data Encryption
Current RSA-768 take 3 year
1024 bit number will take 3000 year
But Quantum computer can solve in
minutes
RSA= Public-key encryption protocol
Ron Rivest , Adi Shamir , Leonard Adleman

What can Quantum Computer do?
Application :  Factorisation (data security)
 Physical modelling (climate , economic , engineering)
 Simulation (chemistry ,material)
 Data bases searching (bioinformatics)

Abacus of Quantum computer
Canadian start up company D-wave demonstrate a 30 Q-bit Quantum computer .
The Computer solve the Sudoku puzzle and other pattern matching problems.

Summary :
 A quantum computer is a machine that performs calculations based on the laws of
quantum mechanics, which is the behavior of particles at the sub-atomic level.
 David J Wineland And Serge Haroche were Awarded with the Nobel Prize for
their work regarding measurement and manipulation of individual Quantum
Systems in 2012.
 Quantum computer use Q-bits to do operation. Electron, proton can be use as Q-
bits.
 Superposition and Entanglement are main building block of Quantum computing
and these property speed up Quantum computer exponentially.
 Every time we add a Q-bit we double the computation power of Quantum
computer .

Quantum computing seminar

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Quantum computing seminar