This document provides an overview of quantum computers, including a brief history of computing technology, limitations of current computing approaches, and the theory behind quantum computing. Quantum computers use quantum particles and properties like superposition and entanglement to perform exponentially more computations than digital computers. While quantum computers currently exist only as theoretical constructs or limited prototypes, algorithms like Shor's algorithm show their potential to solve problems much faster than classical computers for applications like factoring large numbers. Several research groups worldwide are working to advance the technology with the goal of developing fully functional quantum computers within the next 10-20 years.

1. Quantum Computers

2. Overview
 Brief History Computing – (generations)
 Current technology Limitations
 Theory of Quantum Computing
 How it Works?
 Applications
 Timeline
 Questions

3. History
Abacus
Gear Driven
Integrated Circuits
Over 200 million transistors.

4. Moore’s Law
In 1965 Gordon Moore predicted that
number of transistors per square inch on
integrated circuits had doubled every year
since the integrated circuit was invented.
Moore predicted that this trend would
continue for the foreseeable future.
This has held true …….. So far

5. Moore’s Law (cont.)
Recently Gordon Moore announced that
his prediction in 1965 would not remain
true for much longer.
The Microprocessor Industry was getting
closer to the limits of the current
technology.
The ability to put transistors on chips was
approaching the atomic level.

6. Stretching the limits
Intel has announced new SRAM chips for
high density memory.
Contains 330 million transistors.
Pentium IV has 30 million transistors

7. Problems …
•Current technology is not having difficulty
adding more transistors….
•At current rate transistors will be as small as
an atom.
•If scale becomes too small, Electrons tunnel
through micro-thin barriers between
wires corrupting signals.

8. Quantum Computers
• Completely new approach to
computing.
• Uses quantum particles to achieve
computation.
•Still Theoretical.

9. Entanglement
 Albert Einstein Baffled
 Coined phrase “spooky action-at-a-
distance”
 Still remains a mystery
 Superposition

10. Two States Are Better Than One!
• Digital Computers rely on O’s and 1’s
• Voltage produces high and lows
• Can only have one state
• Quantum computers can have
multiple states
• Two places at once

11. Example
• Reflecting photons off half -silvered
mirror (deflects half the light)
• Where do you think the photon
landed?

12. Example (cont.)
• Proof ….. Both detectors record
photon?
• Qubit – Quantum bit is in
superposition (0 and 1).

13. Why Is This Helpful?
• Multiple computations simultaneously
• Computing power is exponential

14. Digital vs. Quantum
• Digital produces serial results, Even with
threads!
• Quantum is truly concurrent
• Digital computers need an exponential amount
of resources to accomplish a task
• Quantum computers only performs 2^n
computations. (n = number of Qubits)

15. The Larger the problem …
• Because of the exponential factor the
larger computations save more
resources than smaller ones.
• Adding large calculations to existing
algorithms does not complicate
computation
• Efficiency due to Qubits

16. Power of Algorithms
 Multiplication Algorithms assist in
large computations
 Quantum Algorithms can speed up
processes by using logic
 instructions such as `... and now
take a superposition of all numbers
from the previous operations...';

17. Algorithms (cont.)
 Will be extremely effective in any logic
based algorithms such as factoring large
numbers.
 Algorithms are not just theoretical
anymore
 In 1994 Peter Shor, of Bell Labs devised a
polynomial time algorithm for factoring
large numbers on a quantum computer.

18. Status …
 Quantum Algorithms do exist (Peter Shor)
 Intellectual hives devoted to quantum
computing: Oxford University, University of
Innsbruck in Austria, Boulder-Colorado, labs of
the National Institute of Standards & Technology
(NIST) , Los Alamos National Laboratory
Massachusetts Institute of Technology , many
others.
 Even Microsoft Research in Redmond, Wash.,
now counts a quantum computer scientist
among its theorists.

19. Status (cont.)
 Rudimentary Quantum Computers exist
 December 19, 2001 – IBM performs
Shor’s Algorithm
 Quantum computing is so complex that
expanding on simple operations is still 10
–20 years away.
 Most well known QC’s based on nuclear
magnetic resonance (NMR).

20. Who’s Who in Quantum
Computing
 Albert Einstein – Theorized about
quantum computation
 Richard Feynman – considered simulation
of quantum-mechanical objects by other
quantum systems in 1982
 Peter Shor – developed first quantum
algorithm in 1994
 A ton of well-formed teams ……

21. Timeline
 Desktop Quantum computers expected by
many within 20 years
 Faster than anticipated progress

22. Questions ?