i am a student doing diploma in Bangalore . I created this powerpoint for my professional practice lab

1. SEMINAR ON
QUANTUM COMPUTERS
PRESENTED BY :- APRAMEYA.B.R
RAHUL.R

2. TODAY WE WOULD BE GOING THROUGH
• INTERDUCTION
• COMPUTING GENERATIONS
• INTERDUCTION TO QUANTUM COMPUTERS
• Why quantum computers
• What is quantum computing
• Quantum logic and representation
• Wheare did the idea come from
• Basic positons of quantum bits
• What makes quantum computer different from other computers
• Quantum gates

3. INTRODUCTION
Since 1960S the power of computers are growing exponentially allowing computers to become smaller and
smaller with more this process is about to meet its physical limits . Computer parts are approaching the
size of an atom

4. COMPUTING GENERATIONS
• First generation computing(1940-1956) vacuum tubes
• Second generation computing(1956-1963) transistors
• Third generation computing (1964-1961) integrating circuits
• Forth generation computing(1971-present) microprocessors
• Fifth generation computing(present) artificial intelligence

5. Vaccume tubes

6. BRIEFING ABOUT QUANTUM COMPUTING
• Computer chip contains modules which contains modules, which contains logic gates, which contains
transistors, a transistors is a Smallest part of the computer ,basically it’s a switch that can block or open
the way for the information passing through it . This information is made up of bits which can be set
either to 0 or 1 , combination of serval bits can be used to represent more complex information
transistors are combined to create logic gates .combinations of logic gates form modules. Modules ca be
used to perform operations like any athematic functions and logical functions. Which can calculate any
complex problems like astrophysics , deriving equations etc..

8. WHY QUANTUM COMPUTING
• Today a typical scale of transistor is 14 nanometers which is about 500 times smaller then a red blood
cell. as transistors are shrinking only to the size of on few atoms. electrons may transfer themselves to
other side of the blocked passage
• BY 2025 to 2030, transistors will be so small and it will generate so much heat that the standard silicon
technology may even collapse.
• Already intel has implemented 14 nm silicon technology
• If scale becomes too small electrons may tunnel(pass) through the blocked path and corrupting the
signals

9. RichardFeynman envasionsof
quantum computing
Peter Shor develops
algorithm that could be
used forquantum
code- breaking
Eddie Farhi at MIT
develops idea for
adiabaticquantum computing
David Deutschdescribes universal quantum computer
D-Wave Systems founded by Geordie Rose
D-WAVE were the first one to introduce to a commercial quantum computer

10. WHAT IS QUANTUM COMPUTING
• Quantum computer is a computer which performs
calculations based on the LAW of quantum mechanics

11. QUANTUM LOGICS AND REPRASENTATION
 Quantum Computers use quantum mechanical phenomena-
• Entanglement
• Superposition
 Quantum computational operations were executed on a very small number of Qubits
(quantum bits)

12. BASIC CONSEPT OF QUANTUM DATA BITS(QBITS)
• In existing computers, all information is expressed in terms of 0s and 1s, and the entity
• that carries such information is called a "bit.“
• A bit can be in either a 0 or 1 state at any one moment in time.
• A quantum computer, on the other hand, uses a “quantum bit” or "qubit" instead of a bit.
• A qubit also makes use of two states (0 and 1) to hold information, but in contrast to a bit, In this state, a qubit can
take on the properties of 0 and 1 simultaneously at any one moment.
• Accordingly, two qubits in this state can express the four values of 00, 01, 10, and 11 all at one time .

13. REPRESENTATION OF DATA IN QUANTUM
COMPUTING USING QUBITS
• A bit (0 or 1) 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>.
State 0
State 1

14. SQUID A QUANTUM TRANSISTOR

15. SUPERPOSITONS :- HOW IT WORKS

16. WHAT MAKES QUANTUM COMPUTERS DIFFRENT
• There is much that is different between quantum computers and classical computers.
• But am going to explain only few:
1. Quantum Super Positioning
2. Quantum Entanglement
3. Quantum Teleportation

17. KEY QUANTUM EFFECTS
superpositioning Quantum Tunneling Entanglement

18. QUANTUMSUPERPOSITION
• Super Positioning is a big word for an old concept: that 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.
• One may think of this as a vector of the probabilities drawn in a two- dimensional coordinate system of the
Complex plane, that is, coordinates of the form x+iy where
• x is a coordinate on the Real number line, and
• y is a coordinate on the Imaginary number line.
• Classical bits are either vectors of 0 or 1 and have no Imaginary component.

19. OPERATIONS ON QUBITS - REVERSIBLE LOGIC
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.
Ex.
The AND Gate
A
B
C
A B C
0 0 0
0 1 0
1 0 0
1 1 1
Input Output
In these 3 cases,
information is being
destroyed

20. QUANTUM GATES
 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)

21. QUANTUM LOGIC GATES
 Commonly used gates
Hadamard gate
Pauli-X gate
Pauli-Y gate
Pauli-Z gate
Phase shift gates
Swap gate
Controlled gates

22. QUANTUM GATES - HADAMARD
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

23. QUANTUM GATES - CONTROLLED NOT
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
A B A’ B’
0 0 0 0
0 1 1 1
1 0 1 0
1 1 0 1
Input Output
Note: The CN gate has a similar behavior
to the XOR gate with some extra
information to make it reversible.
A’
B’

24. EXAMPLE OPERATION - MULTIPLICATION BY 2
We can build a reversible logic circuit to calculate multiplication by 2 using
CN gates arranged in the following manner:
Carry Bit
Carry
Bit
Ones
Bit
Carry
Bit
Ones
Bit
0 0 0 0
0 1 1 0
Input Output
Ones Bit
0
H

25. QUANTUMENTANGLEMENT
 Entanglement is the ability of quantum systems to exhibit correlations between
states within a superposition.
 Quantum entanglement is one of the central principles of quantum physics, though it is also
highly misunderstood.
 In short, quantum entanglement means that multiple particles are linked together in a way
such that the measurement of one particle's quantum state determines the possible quantum
states of the other particles.
 When this happens, the state of the two particles is said to be entangled.

27. QUANTUMTELEPORTATION
• Quantum teleportation is a technique used to transfer information on a quantum level,
usually from one particle to another.
• Its distinguishing feature is that it can transmit the information present in a quantum
superposition, useful for quantum communication and computation.

28. SHOR’S ALGORITHM
• Name after mathematician peter shor, is quantum (an algorithm that runs on a quantum computer) for
integer factorization in 1994. informally, it solves the following problem given an integer N, find its
prime factor
• Example:- factor a number into primes M = p*q
• classical t ~ exp(0(n1/2 log2/3n) = 28,000,000,000,000,000,000,000 years
• Quantum t~0(n3) = 100 seconds

29. A FABRIC OF PROGRAMMABLE ELEMENTS
• In order to go from a single qubit to a multi-qubit processor, the qubits must be connected together
such that they can exchange information. This is achieved through the use of elements known as
couplers. The couplers are also made from superconducting loops. By putting many such elements
(qubits and couplers) together, we can start to build up a fabric of quantum devices that are
programmable. Figure 2 shows a schematic of 8 connected qubits. The loop shown in the previous
diagram has now been stretched out to form one of the long gold rectangles. At the points where the
rectangles cross, the couplers have been shown schematically as blue dots.
•

31. QUANTUM PROCESSOR ADDRESSING
• There are several additional components necessary for processor operation. A large part of the circuitry that
surrounds the qubits and couplers is a framework of switches (also formed from Josephson junctions) forming
circuitry which both addresses each qubit (routes pulses of magnetic information to the correct places on
chip) and stores that information in a magnetic memory element local to each device. The majority of the
Josephson junctions in a D-Wave quantum processing unit (QPU) are used to make up this circuitry.
Additionally, there are readout devices attached to each qubit. During the computation these devices are
inactive and do not affect the qubits' behavior. After the computation has finished, and the qubits have settled
into their final (classical) 0 or 1 states, the readouts are used to query the value held by each qubit and return
the answer as a bit string of 0's and 1's to the end user. Here is a video showing how some of the QPU
elements were combined to produce the computational fabric at the core of the D-Wave One™ 128-qubit
QPU, which pre-dates the current 2000-qubit D-Wave 2000Q™ QPU.
•

32. MANUFACTURING OF QUANTUM PROCESSING UNIT
• QPUs after fabrication in a superconducting electronics foundry. The QPUs are 'stamped' onto a silicon
wafer using techniques modified from the processes used to make semiconductor integrated circuits.
There are several QPUs visible on this wafer image. The largest, near the bottom center, has 128 qubits
connected together with 352 connection elements between them. The qubit/coupler circuits on each
individual QPU are the cross-hatched looking patches visible in this image. This is known as a Rainier
QPU and it was the type of QPU found inside the D-Wave One™ quantum computer.

33. COMPUTER COOLING
• Reduction of the temperature of the computing environment below approximately 80mK is required for
the processor to function, and generally performance increases as temperature is lowered - the lower
the temperature, the better. The latest generation D-Wave 2000Q system has an operating temperture
of about 15 millikelvin. The QPU and parts of the input/output (I/O) system, comprising roughly 10kg of
material, is cooled to this temperature, which is approximately 180 times colder than interstellar space!
Most of the physical volume of the current system is due to the large size of the refrigeration system.
The refrigeration system used to cool the processors is known as a dilution refrigerator.

35. ADVANTAGES:
• Could process massive amount of complex data.
• Ability to solve scientific and commercial problems.
• Process data in a much faster speed.
• Capability to convey more accurate answers.
• More can be computed in less time.
• These are used to protect secure Web pages, encrypted email, and many other types of data.

36. DISADVANTAGES
 Hard to control quantum particles
 Lots of heat
 Expensive
 Difficult to build
 Not suitable for word processing and email.
 Problem of it need of a noise free & Cool Environment.
 Complex hardware schemes like superconductors

37. APPLICATIONS:
• Encryption Technology
• Ultra-secure And Super-dense Communications
• Improved Error Correction And Error Detection
• Molecular Simulations
• True Randomness
• Cryptography
• Searching
• Factorization
• Simulating