A quantum computer uses quantum mechanics phenomena like superposition and entanglement to perform calculations exponentially faster than classical computers. It uses quantum bits (qubits) that can be in superposition of states 0 and 1, allowing massive parallelism. However, quantum computers are very difficult to build due to challenges like decoherence where external noise disrupts the fragile quantum states. If developed further, quantum computers could break current encryption methods and vastly accelerate tasks like database searching and optimization problems.

1. Quantum computer
Presentation by Jay Patel
BCA(sem-6)
Year 2016-17
DUIAS,VALSAD

2. What is quantum computer?
• A quantum computer is a machine that
performs calculations based on the laws of
quantum mechanics

3. Introduction
• Processor is an important part of computer it helps
the computer to perform various tasks
• Processor is made up of numerous transistors

4. Introduction
• The work of
transistors is simple it
acts like switch which
allows to pass
current
• It is basically like a
switch

5. Introduction
• The size of a transistors
have gradually
decreased through years
and is predicted that it
will become a size of an
atom

6. Quantum tunnelling
• Tunnelling is a quantum mechanical effect.
A tunnelling current occurs when electrons move through a
barrier that they classically shouldn't be able to move
through. In classical terms, if you don't have enough energy to
move "over" a barrier, you won't.

7. Qubit
• In normal computers , bits are smallest unit
of information which is either 0 or 1
• Whereas quantum computers use quantum
bit which is also know as qubit
• it can take on two value simultaneously, 0
and 1. this characteristic expands of
producing parallel calculation

8. Quantum superposition
• An electron has dual nature
• It can exhibit as a particle and also as wave
• Wave exhibits a phenomenon known as
superposition of waves
• This phenomenon allows the addition of waves
numerically
• Superposition occur all the time at the quantum
level
• i.e. any quantum object like a electron or photons
is in superposition.

9. Decoherence
• As the number of qubit the increases the
influence of external environment disturb the
system
• This cause the states in the computer to
change in a way that is completely unintended
and is unpredictable rendering the computer
useless

10. Quantum entanglement
• In quantum mechanics it sometimes occurs
that a measurement of one particle will effect
the state of another particle even though
classically there is no direct interactions
• When this happens the state of the two
particles is said to be entangled

11. Quantum parrellism
• It is a method in which a quantum computer
is able to perform two or more computations
simultaneously
• In classical computers parallel computing is
performed by having several processors linked
together
• In a quantum computer a single quantum
processor is able to perform computation on
its own

12. Quantum parrellism
• Parallelism allows a quantum computer to
work on many compulation at once

13. Quantum networking
• One possible use of quantum computers is
that of networking both intranet and internet
• Quantum teleportation using light beams may
be able to carry a great deal of information
• But the issue in this is creating large enough of
light in both locations sending and receiving to
send all the data in reasonable time

14. Encryption
• Current encryption methods work by factoring
small numbers which is easy
• Current encryption numbers use over 400
digits in size which today's computer will take
billions years to process
• A quantum computers will take seconds to
calculate these numbers

15. Need for quantum computers
• That is roughly 200 times smaller than Intel's
brand new architecture
• Would be very useful in research and
algorithm computation
• Database searching : to find something in a
database, a normal computer may have to test
every single one of its entries. Quantum
algorithms need only square root of that time

16. Future prospects
• When processor components reach atomic
scale Moore's law breaks down
• Quantum effects become important whether
we want them or not
• But huge obstacle in building a practical
quantum computer

17. Conclusion
• Quantum computing could provide a radical
change in the way computation is performed
• Classical computer will be larger than
quantum computers for the future

18. References
• https://en.wikipedia.org
• http://www.nova.org.au
• https://www.slideshare.net