Quantum Computers

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

History

Abacus Gear DrivenIntegrated CircuitsOver 200 million transistors.

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

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.

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

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.

Quantum Computers• Completely new approach to computing.• Uses quantum particles to achieve

computation.•Still Theoretical.

Entanglement Albert Einstein Baffled Coined phrase “spooky action-at-a-

distance” Still remains a mystery Superposition

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

Example

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

Example (cont.)

• Proof ….. Both detectors record photon?

• Qubit – Quantum bit is in superposition (0 and 1).

Why Is This Helpful?

• Multiple computations simultaneously• Computing power is exponential

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)

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

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...';

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.

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.

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).

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 ……

Timeline Desktop Quantum computers expected by

many within 20 years Faster than anticipated progress

Questions ?