Nanocomputers

1. Nanocomputers Patrick Kennedy John Maley Sandeep Sekhon

2. History • Since Feynam’s “There is Plenty of Room at the Bottom”, nanotechnology has become a hot topic. • With computers being an integral part in today’s society, nanocomputers are the easiest and most likely route in which computer development may continue.

3. Moore’s Law • According to Moore’s Law, the number of transistors that will fit on a silicon chip doubles every eighteen months. • Presently, microprocessors have more than forty million transistors; by 2010 they could have up to five billion. • By the year 2020, the trend line of Moore’s law states that there should be a one nanometer feature size.

4. Transistors • The transistor is the most important component of a computer today. • More transistors = larger computer memories and more powerful computers

6. What is a nanocomputer? • The general definition of a nanocomputer is a computer which either uses nanoscale elements in its design, or is of a total size measured in nanometers.

7. Types of nanocomputers • Electronic • Mechanical • Chemical • Quantum

8. Electrical Nanocomputers • Electronic nanocomputers would operate in a manner similar to the way present-day microcomputers work. • Due to our fifty years of experience with electronic computing devices, advances in nanocomputing technology are likely to come in this direction. 

9. How it works • Although electronic nanocomputers will not use the traditional concept of transistors for its components, they will still operate by storing information in the positions of electrons.  • There are several methods of nanoelectronic data storage currently being researched.  Among the most promising are single electron transistors and quantum dots. • All of these devices function based upon the principles of quantum mechanics.

10. Transistor replacements • Resonant Tunneling Transistor • Single Electron Transistor • Quantum Dot Cell • Molecular Shuttle Switch • Atom Relay • Refined Molecular Relay

11. Single Electron Transistors • The single electron transistor (SET) is a new type of switching device that uses controlled electron tunneling to amplify current

12. SET • When the gate voltage is set to zero, very little tunneling occurs. • The charge transfer is continuous. • This voltage controlled current behavior makes the SET act like a field effect transistor, just on a smaller scale.

13. Resonant Tunneling Device • RTD’s are constructed from semiconductors hetero-structure made from pairs of different alloys III-IV alloys.

14. Quantum Dots • They are nanometer scaled “boxes” for selectively holding or releasing electrons. • The number of electrons can be changed by adjusting electric fields in the area of the dot. • Dots range from 30nm to 1 micron in size and hold anywhere from 0 to 100s of electrons.

15. Quantum Dot Cell • Logic gates can be created using dot cells.

16. Molecular Shuttle Switch • The shuttle is a ring shaped molecule the encircles and slides along a shaft-like chain molecule. • The shaft also contains a biphenol and a benzidine group which serve as natural stations between which the shuttle moves.

17. Atom Relay • It consists of a carefully patterned line of atoms on a substrate. • Consists of two atom wires connected by a mobile switching atom.

18. Refined Molecular Relay • Based on atom movement. • Rotation of molecular group affects the electric current.

19. Comparison

20. Mechanical Nanocomputers • Mechanical nanocomputers would use tiny moving components called nanogears to encode information. • Other than being scaled down in size greatly, the mechanical nanocomputer would operate similar to the mechanical calculators used during the 1940s to 1970s.

21. Mechanical Nanocomputers • Eric Drexler and Ralph Merkle are the leading nanotech pioneers involved with mechanical nanocomputers. • They believe that through a process known as mechanosynthesis, or mechanical positioning, that these tiny machines would be able to be assembled.

22. How it works • In today’s conventional microelectronics, voltages of conducting paths represent digital signals, and logic gates used as transistors. • For the mechanical nanocomputer, the displacement of solid rods would represent the digital signal. • Rod logic would enable, “the implementation of registers, RAM, programmable logic arrays, mass storage systems and finite state machines

23. Nanosystems • Drexler declared that the nanocomputer could contain about, 106 transistor like interlocks within a 400nm cube, have clock speeds of about 1 GHz with an execution time of about 1000 MIPS; all with only about 60nW of power consumption. • Ralph Merkle stated that, “In the future we'll pack more computing power into a sugar cube than the sum total of all the computer power that exists in the world today.”

24. Problems! • Slow process that would be required to assemble the computers. • Hand made parts would have to be assembled one atom at a time by an STM microscope. • Due to this slow and tedious process, researchers also believe that reliability of the parts would suffer.

25. Quantum Nanocomputer • The basis for the idea of a quantum nanocomputer came from the work of Paul Benioff and Richard Feynam during the 1980s.

26. How it works • The quantum nanocomputers are planned to hold each bit of data as a quantum state of the computer • By means of quantum mechanics, waves would store the state of each nanoscale component. • Information would be stored as the spin orientation or state of an atom.

27. How it works • With the correct setup, constructive interference would emphasize the wave patterns that held the right answer, while destructive interference would prevent any wrong answers.

28. Problems with Quantum computers • The main problem with this technology is instability. Instantaneous electron energy states are difficult to predict and even more difficult to control. • An electron can easily fall to a lower energy state, emitting a photon • A photon striking an atom can cause one of its electrons to jump to a higher energy state.

29. Chemical Nanocomputers • Also known as biochemical nanocomputers, they would store and process information in terms of chemical structures and interactions. • The development of a chemical nanocomputer will likely proceed along lines similar to genetic engineering. • Engineers must figure out how to get individual atoms and molecules to perform controllable calculations and data storage tasks

30. Advances • In 1994, Leonard Adelman took a giant step towards a different kind of chemical or artificial biochemical computer. • He used fragments of DNA to compute the solution to a complex graph theory graph.

31. Adelman’s methods • Adleman's method utilized sequences of DNA's molecular subunits to represent vertices of a network or "graph". • Combinations of these sequences formed randomly by the massively parallel action of biochemical reactions in test tubes described random paths through the graph. • Adleman was able to extract the correct answer to the graph theory problem out of the many random paths represented by the product DNA strands.

32. Problems • These systems are largely uncontrollable by humans. • Limited problem domain, lacking efficient input and output techniques.

33. Big problems • Though each nanocomputer has its own set of problems, each share some common problems. • A way must be found to manufacture components on the scale of a single molecule. • How to actually constructing a nanoelectric device.

34. The Interconnect Problem • Perhaps the greatest problem is something termed the "Interconnect Problem." • Basically, it's the question of how to interface with the nanocomputer. • With such a dense computational structure, how does one get information in or out? • There so many separate elements that there would have to be a multitude of connections within the computer itself.

35. Future of nanocomputers • Nanotechnology has huge potential in building smaller and smaller computers. • Far greater amounts of information would be stored in the same amount of space. This has enormous space-saving implications. • Someday, all the books in the world could fit into the space of a square inch. Such efficient data storage has great potential for business and scientific research in all fields. • Such microcomputers also have great potential for the entertainment industry. With such great data storage capacity, extremely elaborate computer games and virtual reality environments could be created.

36. Resources • 1. http://www.mitre.org/tech/nanotech/futurenano.html • 2. http://whatis.techtarget.com/definition/0,,sid9_gci514014,00.html • 3.http://searcht.aimhome.netscape.com/aim/boomframe.jsp?query=mechanical+nanocomputers&page=2&offset=0&result_url=redir%3Fsrc%3Dwebsearch%26requestId%3D7eb7002b08196fa7%26clickedItemRank%3D18%26userQuery%3Dmechanical%2Bnanocomputers%26clickedItemURN%3Dhttp%253A%252F%252Fwww.rootburn.com%252Fportfolio%252Fnano%252F%26invocationType%3Dnext%26fromPage%3DAIMNextPrev%26amp%3BampTest%3D1&remove_url=http%3A%2F%2Fwww.rootburn.com%2Fportfolio%2Fnano%2F • 4. http://washingtontimes.com/upi-breaking/20050317-124226-2271r.htm • 5. A. Aviram, M. Ratner, “Molecular Rectifiers” Chem.phys letter Vol. 29. pgs 277-283

37. Questions??