1. CSC 110 – Fluency in Information Technology Ubiquitous Computing Quantum Computing
Dr. Curry Guinn

2. Today’s Class What’s ahead Ubiquitous Computing
Quantum Computing (is to computing as nuclear fusion is to energy)

3. What’s Next? Today Future of Computing Nov 26 Wed No Class
Nov 28 Fri No Class.
Dec 01 Mon Review
Dec 03 Wed Exam 2
Dec 10 Wed Final Exam Due

4. Ubiquitous Computing (Ubicomp, Pervasive Computing, Ambient Intelligence)
“The most profound technologies are those that disappear. They weave themselves into the fabric of everyday life until they are indistinguishable from it...”
Mark Weiser (1991), The Computer for the 21st Century, Scientific American,

5. “Moore’s Law of User Interfaces”
“The number of computers per user will double every two years.”
Source: [Vertegaal, 2003]

6. Major Trends in Computing
Source: Weiser and Brown, 1998

7. Situation Today?
How many personal computing devices do you regularly use?

9. Wireless Body Area Network (WBAN)

11. Intelligent Home Objectives Application Scenario
Ambient Light Sensor, Humidity Sensor, Temperature Sensor for comfort
Blind Actuators to enable natural lighting
Smart furniture like Chair, Table, Refrigerator, Bed, Mirrors etc with built in sensors
Treadmill & other gym. equipment
Gas leakage sensor in kitchen
Alarms & Reminders
Powerline Communication Control
Wireless communication with central control unit
Objectives
Maximize comfort
Minimize cost
Safety & Security
Application Scenario
RFID at doorstep – identification
Camera at doorstep
Displays, Cameras, Mikes & Speakers for inter-house communication
Floor Pressure Sensor - sensing

12. Example of Natural Gestures: DreamSpace
Source:

13. Social Issues
Access rights
Secure storage
Users in control

14. Security, Privacy, Trust
What data do I wish to expose? To whom?
Who can presently access my data?
How can I retract data exposed?
Who am I communicating with?
How do can the privacy of my communication and communication patterns?
Who do I trust as a source of information?
How do I convince others that I am trustworthy?
How to make systems simultaneously secure and usable?

15. Ubicomp Nightmare

16. Quantum Computing
Going beyond Moore’s Law

17. Our goal for today
Understand about quantum computing that you can process news articles like

18. What is the promise of quantum computers?
Computing power has increased exponentially since the 1940s.
Current techniques will reach a limit.
Current computers are limited in solving certain mathematical problems.
These problems are used in today’s current encryption methods.
Accurately modeling quantum mechanical processes.

19. Why Quantum Computing?
By 2020 we will hit natural limits on the size of transistors
Max out on the number of transistors per chip
Reach the minimum size for transistors
Reach the limit of speed for devices
Eventually, all computing will be done using some sort of alternative structure
DNA
Cellular Automaton
Quantum

20. Background The idea of the quantum computer first immerged in 1981.
Richard Feynman
A quantum computer uses the physical characteristics of atoms in order to create powerful computational devices.

21. "Do not take the lecture too seriously. just relax and enjoy it
"Do not take the lecture too seriously just relax and enjoy it. I am going to tell you what nature behaves like. If you will simply admit that maybe she does behave like this, you will find her a delightful, entrancing thing. Do not keep saying to yourself "But how can it be like that?" because you will get into a blind alley from which nobody has yet escaped. Nobody knows how it can be like that."
Richard Feynmann on Quantum Mechanics.

22. Strange aspects of quantum mechanics:
Superposition – object doesn’t have definite properties (location, speed) but has probabilities over them.
Measurement – object’s properties collapse to definite value when measured, collapsing also properties of other entangled objects.
Entanglement – properties of many particles can be correlated.

23. Double-Slit Experiment
How does electron passing thru top slit know to avoid mid point if bottom slit is open?
We can never catch an electron “red-handed” behaving bizarrely
If we place detector then pattern turns to be as expected.

24. Qubits Quantum Bits: Qubits
The basic unit of a quantum computers is the qubit.
Acts like a normal bit in the fact it can be a one or zero.
Because of superposition, a qubit can also be both at the same time.
This superposition allows for every possible output or input to exist at the same time.
Ex. 2-bit word would be 00,01,11,10 all at the same time.

25. Bits and Qubits
The common characteristic of any digital computer is that it stores bits
Bits represent the state of some physical system
Electronic computers use voltage levels to represent bits
Quantum systems possess properties that allow the encoding of bits as physical states
Direction of spin of an electron
The direction of polarization of a photon
The energy level of an excited atom

26. Spin States An electron is always in one of two spin states Notation:
“spin up” – the spin is parallel to the particle axis
“spin down” – the spin is anti-parallel to the particle axis
Notation:
Spin up:
Spin down:

27. Qubit A qubit is a bit represented by a quantum system By convention:
A qubit state 0 is the spin up state
A qubit state 1 is the spin down state 1

28. A qubit is governed by the laws of quantum physics
While a quantum system can be in one of a discrete set of states, it call also be in a blend of states called a superposition
That is a qubit can be in: 1
c c1
|c0|2+|c1|2 = 1 1

29. Cryptography (or why the NSA is interested in quantum computing)
Current encryption methods work by factoring numbers.
Ex. 12=2*2*3.
Very easy to do for small numbers.
Current encryption numbers use over 400 digits in size.
Today’s computers would take about a billion years to factor these numbers.

30. So How Hard is Factoring?

31. Cryptography (Continued)
1994 Peter W. Shor of AT&T deduced how to take advantage of entanglement and superposition to find the prime factors of an integer.
Shor found that a quantum computer could accomplish this factoring much faster in principle than a classical calculator.

32. Cryptography (Continued)

33. Quantum Computer Designs
NMR (Nuclear Magnetic Resonance)
This is just one technique

34. NMR (Nuclear Magnetic Resonance)
Developed at IBM by Issac Chaung.
NMR was thought of in 1996
Protons and Neutrons have spin.
In a normal atoms these spins cancel out.
In isotopes there are extra neutrons.
These extra neutrons create a net positive or negative spin in an atom.

35. NMR How to implement a logic operation. Lining up all the spins
A molecule is suspended in a solvent
The solvent is then put into a spectrometer’s main magnetic field.
This magnetic field aligns all the spins.
Radio frequency pulse.
One of the atoms’ spins will flip or not flip depending on the spin of the other atoms.
Multiple pulse sequences.
A quantum algorithm.

36. NMR (example) Example of radio frequencies interacting with spin.
Current NMR Machine

37. NMR (Pro’s & Cons) Pro’s Con’s
Nucleus is naturally protected from outside interference.
Once the spins are lined up they will stay in the proper order for a long time.
Nuclear qubits already exist in nature.
Technology for manipulating these qubits already exists.
Hospital magnetic resonance imaging.
Con’s
Very large in size.
Many are 10 feet tall.

38. NMR (In The Works) Currently NMR machines 3 and 7 qubit machines.
Development by IBM to create a 10 qubit machine is in the works.
There is also development of small, room temperature NMR machines for more practical uses.

39. Current Challenges Number of bits in a word.
12-qubit machines is the most advanced to date.
Difficulty with large words is too much quantum interaction can produce undesired results. All the atoms interact with each other.
Physical size of the machines.
Current machines are too large to be of practical use to everyday society.

40. IBM’s Implementation
A modification of Shor’s algorithm was implemented by IBM in 2001 using a “designer molecule” with 7 individually addressable qubits. NMR (nuclear magnetic resonance) techniques enabled them to factor 15.

41. Implementation
Scaling up for larger numbers is theoretically unlimited; practically, error-correcting codes will be required
If you can build a big enough quantum computer, you can crack RSA-1024 (about 300 decimal digits) in your lifetime.

42. Wrap-up Mon, December 1: Review for Exam 2 Wed, December 3: Exam 2
In the meantime, study chapter questions on Blackboard.
For Exam 2, you may bring one 8 ½ x 11 inch sheet of paper with whatever you want on it (front and back).