Quantum computing and quantum communications utilize principles of quantum mechanics such as superposition and entanglement to process and transmit information in novel ways. Current research is exploring how to build reliable quantum computers and networks using technologies like ion traps, quantum dots, and optical methods. While still in early stages, quantum information science shows promise for solving computationally difficult problems in fields such as artificial intelligence, cybersecurity, and drug discovery. Pioneering work by groups like D-Wave, IBM, and China are helping advance our understanding of how to harness quantum effects for powerful new computing and communication applications.

1. Quantum Computing
&
Quantum Communications
by
Srinivasarao Bukkuru
Dept. of Nuclear Physics
Andhra University

2. Quantum Computing:
• Quantum Mechanics: A branch of physics which is the fundamental
theory of nature at small scales and low energy levels of atoms and
subatomic particles
• At this level, particles behave in strange ways, taking on more than one
state at the same time, and interacting with other particles that are very
far away - Superposition & Quantum entanglement - will be discussed
later on.
• Quantum computing uses these quantum phenomena to process
information in a novel and promising way.

3. Classical Computers: "Today's comupters"
• make use of the flow of electrons in electrical and electronic circuits
• Process the information in the form of bits or binary digits ( 0 or 1)
• Served for decades in the development of almost everything from health
care to online shopping..
But..

4. But..
• there are many problems that classical computers will simply never be able to
solve.
• Examples:
• Simulation of quantum systems - Idea behind the quantum computing by Feynman
• Trillions of connections in the human brain
• Optimization problems - cancer Radiotherapy - involves thousands of variables and constraints - requires
many simulations until an optimal solution is determined
• AI - Machine Learning: Machines learn to recognize objects by detecting recurring patterns
• Medicine & Materials: To untangle the complexity of molecular and chemical interactions leading to the
discovery of new medicines and materials.
• Cloud Security: Making cloud computing more secure by using the laws of quantum physics to keep private
data safe no matter where it is stored or processed.
• Financial Services: Finding new ways to model financial data and isolating key global risk factors to make
better investments.
For the ever growing need of powerful computation and smaller devices..

5. Why Quantum Computers?
• Moore's law is slowing down and by 2020 it will be
flattened out.
• Moore's law referes to an observation made by
Intel co-founder Gordon Moore in 1965. He noticed that
the number of transistors per square inch on integrated circuits had doubled every
year since their invention.
Transistors can not be made smaller further since the
Quantum Mechanics starts to take over it..
courtesy: Google Images

6. History of Quantum Computers
• 1981 - Feynman proposed the idea of creating machines based on the laws
of Q.M. instead of the laws of C.M.
• 1985 - David Deutsch developed the Quantum Turing Machine (Q.T.M.)
showing that quantum circuits are universal.
• 1994 - Peter Shor came up with a quantum algorithm to factor very large
numbers (O(N)).
• 1997 - Lov Kumar Grover developed a quantum search algorithm,
known as "Grover Algorithm" with O(√N) complexity.
courtesy: Google Images

7. History of Quantum Computers cont..
• 1998 - The first working NMR quantum computers demonstrated.
• 2001 - Researchers demonstrated Shor's algorithm to factor 15
• 2006 - Scientists at MIT develop the first working 12 - qubit platform.
• 2009 - First universal programmable quantum processor is unveiled.
• 2011 - D-Wave systems announced the 1st commercial quantum computer.

8. History of Quantum Computers cont..
• 2012 - D-Wave Systems reveals a 512-qubit processor (D-Wave Two)
• 2012 October - Nobel Prizes were
presented to David Wineland and Serge Haroche
for measuring and manipulating quantum systems.
• 2012 December - The 1st Quantum Computing
Software company 1QBit was established.

9. Current Status of Quantum Computers
• June 2015 : D-Wave Systems Breaks the
1000 Qubit Quantum Computing Barrier
• June 14, 2017: D-Wave Systems
announced it's 2000 Quantum Computer.
ORNL, Google, NASA, USRA, CyberSecurity upgraded to D-Wave
2000Q to support their pioneering research on how quantum computing
can be applied to artificial intelligence, machine learning, and difficult
optimization problems.

10. The 3 Giants working on Q.C.
17Q- commercial prototype30Q-testing stage

11. Processes/ Technologies involved
• Nuclear Magnetic Resonance (NMR) - nuclear spin
• Ion Trap - Qubits are stored in stable electronic states
of each ion
• Quantum Dot - very small semiconductor particles, only
several nanometres in size with different optical and
electronic properties from their macro sized bodies.
• Optical Method

12. Let's see a Quantum Computer at NASA
courtesy: D-WAVE systems

13. Let's see a Quantum Computer at NASA
courtesy: D-WAVE systems

14. D-WAVE system's 128 qubits processor
courtesy: D-WAVE systems

15. Inside the
Quantum
Computer..
courtesy: IBM-Quantum Lab

16. courtesy: IBM-Quantum Lab

17. How do Quantum Computers work?
• Quantum computers are based on qubits, which operate according to two key
principles of quantum physics: superposition and entanglement
• Superposition: Each qubit can represent both "1" and "0" at the same time.
• Entanglement: Qubits in a superposition can be correlated with each other; that
is, the state of one (whether it is a 1 or a 0) can depend on the state of another.
Using these two principles, qubits can act as more sophisticated switches, enabling
quantum computers to function in ways that allow them to solve difficult problems
that are intractable using today’s computers.

18. More about the "Superposition"
courtesy: A K Ahmed, PhD thesis, Helwan University

19. Advantage of quantum "Superposition".
courtesy: RF Wireless World - http://www.rfwireless-world.com & Google Images

20. Before entanglement.. Let's know "Polarisation"

21. more about Quantum Entanglement
There is no known means for communication between the particles,
which at the time of measurement may be separated by arbitrarily large
distances.
courtesy: wikipedia

22. How to create entangled pair
Courtesy: Centre for Quantum Technologies, National University of Singapore
β - BaB2O4 or BBO
Appl. Phys. A 52, 6 (1991) 359-368
Chin. Opt. Lett. 14, 2 (2016) 021404

23. More about "Entanglement"
• Entangled pair can be created by many ways
Few ways to obtain entangled pair:
• a subatomic particle decays into an entangled pair of other
particles.
• Particles produced in "Pair production".
• By using radioactive Na22 (entangled γ-photons)
• Hg atoms - Ordinary light, etc.

24. Present status of Dragon's Quantum Computer
Quantum internet is expected
to be up for commercial use by
the end of August in the City of
Jinan, which is a ‘node’ in
the 2000-km quantum link
built between Beijing and
Shanghai.
China’s quantum satellite achieves ‘spooky action’ at record distance of 1200 Km.
Saying a different approach.. not releaving much details.. seems to be 5 qubit
courtesy: Chinese Academy of Sciences, Shanghai & Google images, [Photo: Xinhua, press release: May 25th 2016]

25. Quantum Communication
• Quantum communication science is an area of study based on the idea
that information science depends on quantum effects in physics.
• Sub-fields:
• Quantum computing
• Quantum correction
• Quantum teleportation
• Quantum cryptography

26. Quantum Network
• Optical networks using existing telecommunication fiber can be
implemented using hardware similar to existing telecommunication
equipment.
• At the sender, a single photon source can be created by heavily
attenuating a standard telecommunication laser such that the mean
number of photons per pulse is less than 1
• For receiving, an avalanche photodetector (analog to photomultipliers)
can be used.
• Free space quantum networks operate similar to fiber optic networks but
rely on line of sight between the communicating parties instead of using
a fiber optic connection. Free space networks can typically support
higher transmission rates than fiber optic networks

27. Quantum Network cont..
• Entanglement purification: Quantum decoherence can occur during the
transmission. Entanglement purification allows for the creation of nearly
maximally entangled qubits from a large number of arbitrary weakly
entangled qubits.
• Many existing quantum networks are designed to support quantum key
distribution (QKD) between classical computing environments. In this
application, the quantum network facilitates the sharing of a secret
encryption key between two parties, unlike classical key distribution
algorithms.
• QKD is the "unhackable" quantum communications technology.

28. Principle behind the unhackable QKD technology
Heisenberg's uncertainty principle: one cannot simply
observe a quantum particle (in this case a photon)
without changing that particle's quantum state.

29. Conclusions
• Pioneering Stage
• NEW hardware - Quantum HARDware
• Exploring the new methods of creating better "qubits"
• WHEN?? - will we get a Quantum Computer??

30. If Quantum Mechanics has not
profoundly shocked you, you
have not understood it yet..
-Neils Bohr

31. •Anyone, who claims to
understand Quantum
Theory is either lying or
crazy
- Richard Feynman