This document provides an overview of quantum computers. It begins by explaining that quantum physics must be understood first as quantum computers are based on quantum mechanical principles rather than classical physics. It then defines a quantum computer as a machine that performs calculations based on the laws of quantum mechanics. The document goes on to discuss key quantum properties like superposition and entanglement that quantum computers exploit. It also covers qubits, quantum gates, applications, advantages, challenges, and concludes by stating that quantum computers will require a new way of looking at computing.

1. QUANTUM
COMPUTER

2. BEFORE UNDERSTANDING MORE ABOUT QUANTUM
COMPUTERS WE NEED TO UNDERSTAND THE
CONCEPT OF QUANTUM PHYSICS.
QUANTUM PHYSICS PUTS EVERYTHING INTO
QUESTION. IT DEFIENES EVERY INTUTION WHICH WE
HAVE ABOUT OUR NATURAL WORLD.

3. WWHHAATT IISS QQUUAANNTTUUMM CCOOMMPPUUTTEERR
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.

4. IInnttrroodduuccttiioonn && HHiissttoorryy
 “I think I can safely say that nobody understands
quantum mechanics” - Feynman
 1982 - Feynman proposed the idea of creating machines
based on the laws of quantum mechanics instead of the
laws of classical physics.
 1985 - David Deutsch developed the quantum turing machine,
showing that quantum circuits are universal.
 1994 - Peter Shor came up with a quantum algorithm to factor
very large numbers in polynomial time.
1997 - Lov Grover develops a quantum search algorithm with
O(√N) complexity

5. QQuuaannttuumm PPrrooppeerrttiieess UUsseedd ::--
• Superposition
Definition :-Two things can overlap each other without
interfering with each other. In classical computers,
electrons cannot occupy the same space at the same
time, but as waves, they can.
• IT IS THE ABILITY OF AN OBJECT TO BE MORE THAN 1
THING AT THE SAME TIME
• SO THEY CAN BE THIS AND THAT AT THE SAME TIME

7. EENNTTAANNGGLLEEMMEENNTT
• Entanglement is the ability of quantum systems to
exhibit correlations between states within a
superposition.
• If two objects are quantum mechanically entangled,
then they can be strongly related to each other even
though they are vast distance apart

10. What special aabboouutt QQUUAANNTTUUMM CCOOMMPPUUTTEERR
????

11. QQUUBBIITTSS
• What is a qubit ?
• Well we have studied a lot about in our
ENGG. ,we know that one bit can either store 1
or 0
• But qubit can store 1 and 0 at same time.

12. Representation ooff DDaattaa -- QQuubbiittss
A bit of data is represented by a single atom that is in one of two states
denoted by |0> and |1>. A single bit of this form is known as a qubit
A physical implementation of a qubit could use the two energy levels of an
atom. An excited state representing |1> and a ground state representing |
0>.
Excited
State
Ground
State
Nucleu
s
Light pulse of
frequency l for
time interval t
Electro
State |0> n State |1>

13. BBiittss vv//ss QQuubbiittss
Bits
• The device computes by
manipulating those bits
with the help of logic gates.
• A classical computer has a
memory made up of bits
where each bits hold either
one or a zero.
Qubits
• A qubit can hold a one,a
zero,or,crucially,a superposition
of these,manipulating these
qubits with the help of quantum
logic gates.
• The qubits can be in
superposition of all the classically
allowed states.

14. UNIVERSAL QUANTUM LOGIC GATES
• It is realized with high-finesse microwave cavities
and two-state atoms.
• All possible quantum computations can be built up
with a network of such gates.
• More general output states can be obtained by
adjusting the atom-cavity interactions and adding
another Ramsey zone

15. OOppeerraattiioonn OOnn QQuubbiittss
Due to the nature of quantum physics, the destruction of information in
a gate will cause heat to be evolved which can destroy the
superposition of qubits.
A B C
0 0 0
0 1 0
1 0 0
1 1 1

16. QQuuaannttuumm GGaatteess
 Quantum Gates are similar to classical gates, but do not have a
degenerate output. i.e. their original input state can be derived from
their output state, uniquely. They must be reversible.
 This means that a deterministic computation can be performed on a
quantum computer only if it is reversible. Luckily, it has been shown
that any deterministic computation can be made reversible.(Charles
Bennet, 1973)

17. QQuuaannttuumm GGaatteess -- HHaaddaammaarrdd
Simplest gate involves one qubit and is called a Hadamard Gate (also
known as a square-root of NOT gate.) Used to put qubits into superposition.
H
State
|0>
State |
0> + |1>
H
State
|1>
Note: Two Hadamard gates used in
succession can be used as a NOT
gate

18. QQuuaannttuumm GGaatteess -- CCoonnttrroolllleedd NNOOTT
A gate which operates on two qubits is called a Controlled-NOT (CN)
Gate. If the bit on the control line is 1, invert the bit on the target line.
A - Target
B -
Control
Input Output
A B A’ B’
0 0 0 0
0 1 1 1
1 0 1 0
1 1 0 1
A’
B’
Note: The CN gate has a similar
behavior to the XOR gate with some
extra information to make it reversible.

19. Example Operation -- MMuullttiipplliiccaattiioonn BByy 22
 We can build a reversible logic circuit to calculate multiplication by 2 using CN
gates arranged in the following manner:
Carry Bit
Input Output
Carry
Bit
Ones
Bit
Carry
Bit
Ones
Bit
0 0 0 0
0 1 1 0
Ones Bit
0
H

20. AAPPPPLLIICCAATTIIOONN
SS
 CRYPTOGRAPHY
It has wide application in cryptography (the
method of breaking ciphers).
 TELEPORTATION
 QUANTUM COMMUNICATION

21.  Artificial intelligence
 searching
 encryption problem & quantum
chemistry problem

22. AApppplliiccaattiioonnss::
Chemistry Physics Material Science
&
Engineering
Biology
&
Medicine
Nanotechnology
Business
&
Commerce
Cryptograph
y
Large
DBMS

23. AADDVVAANNTTAAGGEESS
 Much more powerful
Could process massive amount of data
 Faster
Process data in much faster speed
 Smaller
 Improvement to science
Capability to convey more accurate answers
 Can improve on practical personal electronics
Ability to solve scientific & commercial problems

24. Realization && DDiiffffiiccuullttiieess ttoo bbuuiilltt
QQuuaannttuumm ccoommpp..
The quantum computer might be the
theoretician's dream, its realization is a
nightmare
 It is very difficult to scaling the component in
quantum computer
As the number of quantum gates in a network
increases, we quickly run into some serious
practical problems
The more likely it is that quantum information will
spread outside the quantum computer and be
lost into the environment, thus spoiling the
computation

25. CCOONNCCLLUUSSIIOONN
 It discusses an overview of the quantum
computing world.
 It discusses the inevitability of quantum
computers, how they originated, and
what is different about them from
classical computers.
 Quantum computes are coming, and they
will require a new way of looking at
computing

26. REFERENCE
http://wn.wikipedia.org/wiki/quantum computer
http;//bigthink.com
http://www.qubit.org/tutorials
http://sciencedaily.com
http://how stuff works.org

27. TTHHAANNKK YYOOUU