Molecular Computing

A Seminar By:

PANKAJSHARMA

Definition

The field of molecular computing seeks to useindividual molecules to perform functions inelectronic circuitry used for computational processespresently performed by semiconductor devices. 

Individual molecules are hundreds of times smallerthan the smallest features conceivably attainable bySemiconductor technology.

Origin

Inspiration came when, on June 25, 1992, thespace shuttle Columbia thundered into orbitcarrying a most unusual payload:

A purplish looking, coastal swamp marsh bacteriacommonly found in the San Francisco Bay area.

Features…

Can meet modern computational requirements.

(i) Massively Parallel and distributed

(ii) Sleek Sized/ Palm held

(iii) Tremendous processing power

(iv) Outsized Storage capacity (in TB)

(v) Lesser heat radiant

Features (Contd)…

(vi) Use ‘WET’ intelligence ( beyond AI).

(vii) Lesser power requirements

(viii) Multi-dimensional/ Holographic Computing

(ix) Revolution in Technology

1) Bio-molecular Electronics

2) Nanotechnology

Theory Behind…

This bacteria, HALOBACTERIUM HALOBIUM, has a unique pigment found in its cell membrane called bacteriarhodopsin (bR).

bR protein captures incoming energy and converts it into cellular energy for Halobacterium.

bR devices can switch between alternate states, just like the binary logic of today's semiconductor-based digital systems.

Molecular Computing Tree

Molecular Computing

Bio-molecularElectronics Nanotechnology

Ultra fast molecular sized devices grown from biological systems

Miniaturized molecular devices

Bio-molecular approach…

This approach circles around two researches: By Prof. Robert Birge bR light output as information carrying medium. By Dr. Hong bR’s electrical signal as output signal.

Concept of Birge

It states:

The bR molecules will kink out of shape when struck by a green laser.

The altered bR molecules can be made to snap back to their original form if hit by a red laser.

Thus bR can act as the basis for a molecular binary switch

Concept of Hong

Based on Genetic engineering it :

Used chemistry to control the switching by modifying the pH surrounding the protein.

Easily modulates the electrical behavior of his mutant bR device.

Molecular Computing Tree

Molecular Computing

Bio-molecularElectronics

Nanotechnology

Ultra fast molecular sized devices grown from biological systems

Miniaturized molecular devices

Nanotechnology approach…

Richard Potember has patented new kind of storage device called Scanning Tunneling Microscope (STM). This is already been brought in use in form of Digital Versatile Disk (DVD) storing 4.7 GB. This storage is extensible to 20 GB. It has capacity to offer Tera bytes of storage space. Implies no more data compression required to store audio/visual data.

Scanning Tunneling Microscope (STM)

Sharp STM Needle

Storage Material

Needle is brought so close that their respective electrons spinning within their atomic orbits actually overlap

Scanning Tunneling Microscope (STM)

Tetracyanoquinodimethane (TCNQ) +

-When a small potential difference is applied between the STM needle and the underlying material, electrons will 'tunnel' from the needle's tip to the material, or vice versa.

Scanning Tunneling Microscope (STM)

Tetracyanoquinodimethane (TCNQ) +

-The electric field thus induced at the tip of the needle causes REVERSIBLE phase transition in underlying substrate like TCNQ which cause TCNQ to go back and forth from a high impedance state to a low impedance state, thereby yielding specific angstrom-sized domains.

Revelation…

Scanning Tunneling Microscope (STM)

device is designed to do read, write, and erase operations within individual domains whose dimensions are just 30 to 40 angstroms

Vs

present-sized domains on magnetic or electro-optical disc drives are at about one square micron

Storage Capacity (Summary)

bR-based molecular storage devices can: store as much as 480 gigabytes of data. size five cubic centimeters. Be read, written, or erased in as little as

five picoseconds using present laser diode technology.

Pros…

Escalating costs to design and fabricate semiconductor devices.

Bio-molecular systems, like bR, are economical. Can be quickly harvested in a normal working environment (cleanliness restrictions). Can be easily controlled via ordinary chemistry, or

use of the shelf laser diodes no need to build complex and expensive control circuitry.

The continuing revolution in genetics engineering also offers the promise of being able to easily refine and extend the useful features of such biologically-based systems.

Pros…

The weird world of quantum mechanics.As the size of semiconductor materials goes on decreasing,According to Heisenberg's uncertainty principle it is impossible to ever know what is precisely going on in theatomic realm. Obviously, this can cause all sorts of problems, especiallyfor those engineers designing semiconductor systemshaving vanishingly small transistors.

LET US NOW LOOK HOW MOLECULAR SYSTEMS HANDLE IT!!

Answer to Quantum Mechanics Problem

Answer Is

REDUNDANCY

But in semiconductor computers introducing redundant circuits adds to the already high costs and thus is not feasible…

BUT

Answer to Quantum Mechanics Problem

Molecular-based systems can have as many billions of atoms stuffed into even the smallest patch of material. Thousands of molecules can thus be used to carry or encode identical information without worrying about using up all of the available storage capacity.

By taking advantage of this natural redundancy, and using averaged output, one can predict that the data is being handled correctly, despite quantum effects. This particular technique is called

ENSEMBLE AVERAGING

Pros…

In the possible case of semiconductor-based processors, massive heat generation is a big problem.

Molecular systems offer great solution to this problem.

Cons..

Relatively new technology so less reliability Difficult to operate at molecule or atomic realm

because of their size Research and development phase still on Initial costs are large

Conclusion

Though highly promising, but like any radically new technology,

there is a daunting learning and manufacturing curve that must

first be overcome before these molecular devices can be mass

produced. They are still 5 to 10 years away from becoming

commercial reality. Given such projected long lead times, one

could speculate that advances in semiconductor based

systems, as well as in magnetic and laser storage technologies,

might put them on an equal footing with any far off molecular

system.

Bibliography

Relevant Sites:

Vxm.com Calmec.com Ananova.com Howstuffworks.com

Thank You!!

Questions…

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