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This paper gives you basic information about Quantum Computers and also led you to the latest advancement of it. It covers the overview of quantum computers and what are the advantages to develop such a system.
Abstract—This paper consists of introduction to quantum
computers, Theorems related to quantum computers like
superposition and entanglement. Advances and advantages of
quantum computers are also included in this paper. Later on
description of the company named D-wave is also given who is
the only one who makes Quantum processors and how that
Keywords—Quantum computers; Entanglement;
Till now Computers on which we were working on were
based on Principles of Digital electronics whereas Quantum
Computers are based on principles of Quantum Theory.
Quantum Theories like Entanglement, Superposition, etc.
Quantum computers have been made to do complex
calculations or processes which humans can’t do. Digital
Computers encode data into binary bits whereas Quantum
Computers encode data into Q-bits or Quantum Bits. A
Quantum Turing machine is an example of theoretical model of
Quantum Computers. To understand Quantum computers we
first need to understand concept of Superposition and
ABBREVIATIONS AND ACRONYMS
• Alanine: an amino acid used to analyze quantum state
• Flops: Floating point operations per second
• Josephson Junction: tunneling junctions with
• NMR: Nuclear Magnetic Resonance
• Q-bits: Q-bits or qubits are also known as Quantum
bits which are used instead of binary bits in digital
• Trichloroethylene: a chlorinated hydrocarbon used for
quantum error correction
THEOREMS BASED ON QUANTUM MECHANICS
A. Superposition Theorem
In Digital electronics as mentioned above we use digital
binary bits for communication which are either 1 or 0 at a time.
But Q-bits or quantum bits has a property that it can show both
0 and 1 states at a time. They superposes each other while
B. Quantum Entanglement
Quantum Entanglement is nothing but strong correlation
between many pairs of particles. For example if there are two
particles entangled together then they will complement each
other’s spin, momentum, polarization, position, etc. And this
correlation is so strong that, it will exist even if both of the
particles are kept at either ends of the universe. Entanglement
is a very important principle for building Quantum Computers.
Because of this principle scientists and researchers are
concerned only for 1 qubit out of two, if we are talking about
2-Qubit Quantum Computer .
TIMELINE OF QUANTUM COMPUTING
In late 90s physicist came across some problems while
doing complex calculation in Digital Computers. They were
not able to do it quickly or sometimes can’t even solve the
problem. From here the idea of quantum computers came.
First successful effort was made in 1970 by Stephen
Wiesner invented conjugate coding.
Then in 1973 Alexander Holevo gave information about Q-
In 1975 R.P. Poplavskii gave the superposition Theory.
In 1976 Polish mathematical physicist Roman Stainslaw
Ingarden gave information on Quantum information
theory on replacement of Shannon information theory
as it was not directly applicable to Quantum Case.
In 1980 Yuri gave an idea of Quantum computing.
In 1981 Tommaso Toffoli introduced the reversible Toffoli
GATE which together with the NOT and XOR gates
provides a universal set of classical computation.
In 1982 Paul Benioff proposed the first recognizable
theoretical quantum computer.
In 1984 Caharles Bennett and Gilles Brassard used
Wieser’s conjugate coding for distribution of
In1985 David Deutsch described the first theoretical
universal quantum computer.
In 1991 Artur Ekert invented entanglement based secure
In 1993 Dan Simon invented oracle problem of digital
computer for which quantum computers are faster.
In 1994 Peter Shor discovered an important algorithm
called Shore’s Algorithm. Also Ignacio Cirac and Peter
Zoller proposed an experimental realization of the
controlled NOT GATE with trapped ions.
In 1995 Peter shore and Andrew steane togather gave the
first schemes for quantum error correction. Also
Christopher Monroe and David Wineland
experimentally realized first practical C-NOT GATE.
In 1996 Lov Grover invented quantum database search
algorithm. David P. DiVincenzo, from IBM, gave a list
of minimum requirements for creating a quantum
• In 1997 Cory, Fahmy, Havel and Neil Gershenfeld and
Chuang published the first papers realising gates for
quantum computers based on bulk spin resonance, or
thermal ensembles. This technology is based on a
nuclear magnetic resonance (NMR) machine, which is
similar to the medical magnetic resonance imaging
machine. Kitaev described the laws of topological
quantum computation as a method for combating
decoherence. Loss and DiVincenzo gave the Loss-
DiVincenzo quantum computer, using as qubits the
intrinsic spin-1/2 degree of freedom of individual
electrons sooner defined as quantum dots.
In 1998, A 2-qubit NMR quantum computer used to solve
Deutsch’s problem was shown by Johnathan and Mosca
shortly after by Chuang. first execution of Grover’s
algorithm on an NMR computer.
Braunstein and others scientists told that there was no
mixed state quantum entanglement in any bulk NMR
In 2000,5 Qbit NMR computer showed at technical
university of Munich. First 7-qubit NMR Computer was
showed using Shore’s algorithem.
In 2001, The number 15 was factored using 1018
molecules, each containing 7 active nuclear spins.
In 2003, Pittman and his colleagues and simultaneously
Jeremy O’ Brein and his colleagues at the University of
Queensland, showed quantum controlled NOT gates
using only linear optical elements.
In 2004, pure state NMR Quantum computer showed at
Oxford University and University of York. First five
photon entanglement showed by Jian-Wei Pan’s team.
Harvard and GIT scientists succeeded in transferring
quantum information between “quantum memories” –
from atoms to photons and back again.
In 2006, 12 Qbit quantum computer was patented. Two
dimensional ion trap made for quantum computing
Boehme demonstrates the liability of reading spin data
on a silicon phosphorous quantum computer.
In 2007, best method of Q-bit coupling was made.
Successful demonstration of controllably coupled Q-
bits. Innovation in applying spin-based electronics to
silicon. Diamond quantum register was made. Nitrogen
in Buckminster fullerene used in quantum computing.
Large number of electron quantum coupled. Single
electron Q-bit memory. D-wave systems claims to have
28 Q-bit computer, through this claim has yet to be
verified. Graphene quantum dot spin qubit was
Latest research includes optically addressable nuclear spins
in a solid with a six hour coherence time. Quantum
information encoded by simple electrical pulses.
Quantum error detection code using a square lattice of
four superconducting Q-bits .
WHY QUANTUM COMPUTING?
Since years Computer Scientists and researchers were
trying to increase the speed of Digital Computers. And they
were successful till now. Computers were very slow in earlier
times and were also unable to do complex calculations. Alan
Turing, a British mathematician built world’s first theoretical
Computer in 1930s and he named it ‘Turing Machine’. Based
on his principle we made computers that were able to do
multiple tasks unlike Turing machine, which was able to do
only one task at a time.
As years passed according to Moore’s law we were able to
maintain the increment of number of transistors which is
double after every 18 months. And if we continue to do so
we’ll be able to make processors measured on atomic scale
which will tend to transform into Quantum computers. Such
Quantum computers are also known as quantum Turing
Basically Quantum computers are made to do complex
calculations faster which digital computers cannot do.
Quantum computers works on the principle of superposition
and entanglement as stated in topic 4 and 5, that is why they
are better than Classical Computers.
As the superposition theorem stated in topic 4, qubits can
show both the polarities at the same time due to its ‘spin’. An
electron spins so fast that before capturing or utilizing its first
state, it changes to second state. That means within a particular
time period the probability of the occurrence of 1 or 0 is
approximately 50% for a single qubit. Controlling of qubits can
be done in many ways like ion trap using optical or magnetic
field, quantum dots, semiconducting impurities,
semiconducting circuits, etc. The basic advantage of quantum
computer is that it can do parallel tasks really fast. According
to scientist Deutsch, parallelism allows a quantum computer to
work on a million processes at the same time, while your
desktop Computer works on one. A 30 Q-bit computer’s
processing power is equal to conventional computer that could
work at 10 Teraflops (trillions of floating-point operations per
second). Today's typical desktop personal computers run at
speed measured in Gigaflops (billions of floating-point
operations per second) .
ADVANCES IN QUANTUM COMPUTING
• In 1998, Los Alamos and MIT scientists were able to
spread a single Q-bit across three nuclear spins in each
molecule of a liquid solution of alanine or
trichloroethylene molecules. Spreading out the Q-bit
made it harder to change, allowing scientists to use
entanglement to study correlation between states as an
indirect method for analyzing the quantum
• In 2000, Researchers introduced a 7 Q-bit Computer. It
used NMR to manipulate particles in the atomic nuclei
of molecules of trance – crotonic acid, a simple fluid
consisting of molecules consists of 6 hydrogen and 4
carbon atoms. Nuclear Magnetic Resonance is used to
apply electromagnetic pulses, which force the particle
to line up. This action is done to do parallel processing.
Scientists at IBM developed a 5 Q-bit Quantum
Computer which allowed the nuclei of five fluorine
atoms to react with each other as Q-bits, which can be
programmed by radio frequency pulses and detected by
NMR instruments. Dr. Chuang, and the IBM team was
able to cater a problem called order finding problem
which involves finding the period of the particular
function. Which is a typical aspect of many
mathematical problems present in cryptography.
• In 2001, researchers from IBM and Stanford
successfully showed shore’s algorithem on the
Quantum Computer. Shor's Algorithem is basically a
method for finding the prime factors of numbers
(which plays a crucial role in cryptography). They used
a 7 Q-bit Quantum computer to find the factors of 10.
The computer correctly sorted out that the prime
factors were 2 and 5.
• In 2005, The Institute of Quantum Optics and
Quantum Information declared that scientists had
created the first Q-byte, or series of 8 Q-bits, using ion
traps. Scientists in Waterloo and MIT revised methods
for quantum control on a 12 Q-bit system. Quantum
control becomes harder as systems employ more Q-
• In 2007, D-Wave a Canadian startup company showed
a 16 Q-bit quantum computer. It has catered Sudoku
problem and other pattern matching problems.
Practical Quantum computers are still decades away. If
practical quantum computers can be built, they will
play an important role in factoring large numbers, and
therefore to encode and decode secret information.
Quantum computers must have at least several dozen
Q-bits to be able to solve real time problems, and thus
serve as a feasible computing method .
D-Wave is a company that makes Quantum processors for
making quantum computers. Quantum computers are very
hard to maintain its states as we defined above. As trapped
ions have a lot of energy therefore to cool them we need to
operate the processor in really cool temperature near to 0
Kelvin. One of the processors of D-wave systems is ‘2X’. It is
shielded to 50000 times less than earth’s magnetic field. In a
vacuum pressure it turns out to be 10 billion times lower than
atmospheric pressure. 192 input, output and control lines from
room temperature to the chip. Power consumption of this
system is very less i.e. 25kW and also it won’t rise as it scales
to some thousands of Q-bits. A lattice of 1000 very small
super conducting circuits, well known as Q-bits, is chilled near
to absolute zero to get quantum effects. A user transforms a
problem into a search for the “lowest point in a vast
landscape”. The processor takes all possibilities at a time to
determine the lowest energy needed to from those
relationships. Multiple solutions are given back to the user,
scaled to show best answers. Recently in June 22, 2015 D-
wave breaks the 1000 Q-bit computer barrier. Being the only
manufacturer of quantum processor in the world D-wave
broke the record of making 1000 Q-bit quantum computer in
collaboration with NASA and Google. It is double the size of
the processor they have made so far. It runs on an annealing
algorithm to find out the lowest points, referring to optimal or
near optimal solutions, in a virtual “energy landscape”. As
number of Q-bits increases the amount of parallel processing
increases. Take a 1000 qubit computer, it can consider 21000
possibilities at a time, a search which dwarfs the 2512
possibilities available to the 512 Q-bit D-wave - 2 . D-wave
breaks new record with every succeeding generation it
develops. The processor comprising over 128,000 Josephson
tunneling junctions, are believed to be the most complicated
semiconductor integrated circuits ever successfully
manufactured. Temperature Noise, and precision all play very
important role in how quantum processors solve problem.
Beyond scaling up the technology by doubling the number of
Q-bits, it has also got key technology advances prioritize
around their impact on performance. Apart from achievement
of making more than 100 Q-bit processor other measurable
innovation consists of following:
D. Low Operating Temperature
Previously they were able to achieve temperature that was
near to absolute zero but now in order to enhance the quantum
effect they have achieved the temperature even 40% colder
E. Reduced Noise
With the help of a combination of improved design,
architectural changes and material changes, noise levels have
been decreased by 50%. Low noise increased performance.
F. Increased control circuit Precision
In the testing to date, the improved precision with the noise
reduction has showed improved precision by up to 40%.
G. Advanced fabrication
Latest processor comprises over 128,000 Josephson junctions
in a 6-metel layer planer process with 0.25µm features,
believed to be the most complicated superconductor IC ever
H. New models of use
Latest technology extend the boundaries of ways to exploit
quantum resources. In addition to performing discrete
optimization like its predecessor, firmware and software
updates will make it easier to use the system for sampling
APPLICATION OF QUANTUM COMPUTER
Scientists at D-wave are using their 512-qubit computer to
make artificial intelligence, to improve voice activation device
technology, development of new drugs, climate change
modeling, optimization of traffic control, development of
Robotics and machine navigation and shape recognition.
I would like to express my special thanks to Prof. Dhaval
Shah as well as my director and HOD Dr. P.N. Tekwani and
our section head Dr. D.K Kothari who gave me such a
wonderful opportunity to do the research on the topic
“Quantum Computers” which also helped me increase my
knowledge and I came to know about so many new things that
I am really thankful to them. Also I would like to thank my
parents and friends who helped me a lot in finalizing this topic
within the time period.
Quantum Computers have both advantages and disadvantages.
Advantage is that it can parallelly process data faster than any
other classical computer but if you want to play high
definition games or want to access faster internet then at that
time quantum computers shows slower result than classical