Molecular Cybernetics - "a proposal for the construction of a Quantum Dot Utility Fog"
Microelectromechanical (MEM) Utility Fog familiarized us with the notion of individual polymorphic micro-machines using mechanical changes for movement and optical characteristics. This proposal takes a simpler approach, by configuring Quantum Dot devices in a polygonal shape with a processor at its center it can changes its magnetic effect for movement, confine electrons for optical characteristics, and exchange photons for power and communication.
In 1993, J. Storrs Hall intrigued us with the notion of Utility Fog(1), a substance that could alter its color and shape. Each 'foglet' was a tiny twelve armed micro-machine that mechanically altered its shape and reflectively. With the correct software a brick of Utility Fog could take on the color and shape of about any object conceivable, and then just as quickly change to another.
Unfourtantaley, Utility Fog confronts a few problems, When working on the micro-scale you run into a atomic friction force called "stiction", which tends to jam and erode very small moving parts(2).
Utility Fog might still have a chance at reality in a device called Quantum Dots. This is a solid-state sandwich of semiconductor material that trap electrons and take on atomic characteristics. The capability's of these devices that concern us are controlled photon absorption-emission, controlled magnetic/non-magnetic modification, and controlled optical reflectively. All the effects needed for a solid-state Utility Fog.
QUANTUM DOTS (3)
Quantum Dots have become routine pieces of experimental hardware found in laboratories through out the world. It is simply a layered structure of semiconductor material with control wires, often called a P-N-P junction, though there is nothing simple about the effects that are preceded by this device.
When a Negative Layer of semiconductor is deposited between two Positive semiconductors and attached to a voltage, the electrons pumped in become "trapped" in the Negative Layer and form electron holes in the upper layer at very precise energies. When you configure this P-N-P junction around ten nano-meters or so the size of the trap approaches a quantum-mechanical limit, electrons are no longer able to flow, not able to move as particles, the trapped electrons must instead behave as de Brogile standing waves, or probability density functions, clouds of diffuse electric charge.
Electrons trapped in a Quantum Dot arrange themselves as if they were part of an atom, even though there's no atomic nucleus for them to surround. There repulsive effects combine and each electron try's to get as far away from any other electron as possible, causing orbitals to form similar to the ones they naturally form around real atoms (4).
Now if you embed the electrodes in a fence shaped configuration on the face of the Quantum Dot you can utilize the electrostatic principal for electron control. This is the preferred method for Quantum Dot production, vary the voltage on the fence and you modify the underlying material.
Effects produced by Quantum Dots are numerous, but we are concerned with three basic applications in our drive for Utility Fog: optical characteristics, motive force, and communication.
Optical effects produced by Quantum Dots are achieved by varying the confinement of the electrons (5). If you confine seventy-nine electrons within the trap you produce a artificial atom of pseudogold with the reflective of the color gold.
Quantum Dots also exhibit photon emission (6) in addition to reflective optical characteristics. Place a voltage across the dot and they bring large numbers of electrons and electron holes together at fixed energies, producing photons of very precise wavelengths. This principal behind the key-chain laser pointer.
Controlled photon emission is a communicative tool, though to communicate you must have a receiver as well as a emitter. Quantum Dots rill this feature as well through the photovolatic effect (7). Light shined on the surface of a Quantum Dot generates electron-hole pairs, forcing electrons in one direction and holes in another generating a voltage.
Quantum Dots also have the possibility of producing magnetic forces, "...by either pumping electrons in and out, moving electrons to excited states where there spins are different, or distorting or reshaping the orbital structure."(8). This means that one dot could have a south polarity and another a north polarity and they would be attracted to one another just as natural magnets are. Change the forces so both are the same polarity and the two will push each other away. This is exactly the principal used in every electric motor today.
A individual micromachine of Utility Fog was called a 'foglet', which reacted with numerous other foglets through its tweleve tiny arms. A individual substance of Quantum Dot Utility Fog could be called a "Qmote", for Quantum Mote, and would follow the same interactions minus the mechancis. A Qmote could emit photons or absorb photons for communication and power, (9) modulate there magnetic force for motive action, and configure there electron confinement for correct optical effects.
A Qmote as I lay out here is a cubit ploygone, though it could in principal be a dodechedron, and most likely will be, but for demonstrativeness purposed a cubic form is simpler to wrap the mind around.
A cubit Qmote would have six sides, each a separate Quantum Dot, with a processor at the center of the cube. A processor in this sense is most likely going to have to be a single-electron transistor (SET). (10) This will also allow for consistency in fabrication as a SET is a semiconductor composite made of the same materials as our Quantum Dot.
Programming Qmotes could be achieved through cellular automation principals(11). Each Quantum Dot has numerous states it can take on from photon absorption, to photon emission, and electron confinement, which not only involves the number of electrons trapped but the control of the orbitals as well. Multiply that figure by six for a cubic Qmote and you have your operating parameters.
The outer sides of the mores could then take on optical features, another side might emit photons, another absorbing them in a communication/power chain. The other three sides would very there magnetic effects to link with other Qmotes into a conglomeration of millions, each effecting and being effected by its neighbors.
Manufacturing Qmotes have the same limitations as other areas of nano-technology, the control of individual atoms into a structure. Individual Qmotes may have a surface area around thirty manometers cubed (12), and since there solid-state you have to build them up by layers. Out of the Question? Maybe but we can utilize the same principal in computer chip manufacturing. Molecular-beam epitaxy might be up to the job, it is capable of building up layers only a few atoms thick. If this achievable you would be able to produce Qmotes wafers with billions of individual Qmotes arrayed on it. You then delicately cut them along the outer P-layer to set them free.
With Utility Fog we were concerned with two main characteristics, color and shape, which Quantum Dot Utility Fog achieves, but it has so much more potential. A Qmote is actuality a artificial molecule made up of artificial atoms(13).
A molecule is "the smallest physical unit of a element or compound, consisting of one or more atoms in a element or compound,"(14). A cubic Qmote has six faces that can simulate the atomic characteristics of all atomic states, and then some, which leads one to the equation that a Qmote could be called a artificial molecule.
Andre-Marie Ampere, the famous physicist described cybernetics as the science of governance, (15) and the governance of molecules could be called molecular cybernetics, which seems to have a certain ring to it.
Molecular Cybernetic applications are numerous, they can achieve all the polymorphic actions of Utility Fog in color and shape change. Qmotes are also thousands of times smaller than the foglet design so you get greater detail.
They could be utilized for data storage and computation by arranging them into a FPGA (Field Programmable Gate Array) chip.(16) In fact the computational and data capacity would greatly exceed our current levels by a huge lead.
Since this design rest on photon absorption the use as solar collects is a given (17). Of course, it could as well switch from collecting energy to become anything you want.
There is the possibility they could configure into a tubular design and serve as polymorphic fiber optics, allowing photons to transverse the center area. Or maybe they could even serve as a kind of superconductor power cable with the charge suspended in the center due to overlapping magnetic effects.
Quantum Dots have also been shown to emit highly polarized light (18). This is exactly the effect needed for Quantum Cryptography (19). If you can factor this into each Qmote processor you can not only control Qmotes, but deny control to those without the code.
Medical applications seem the most revolutionary, as a thirty nano-meter Qmote is just slightly larger than the common cellular membrane which is around ten nano-meters. Qmotes should be able to react with numerous biological functions, whether that is mechanically, electrically or chemically.
Dr. J. Storrs Hall gave us a concept that opened a portal to a future of matter that changed for our need. Micro-machines might not be up to the job, but the idea might still be achievable. Maybe tomorrow instead of tossing out that empty carton you reconfigured it into a data storage module.
(1) J.S. Hall, "Utility Fog: A Universal Physical Substance", Vision-21, Westlake, OH; NASA Conference Publication 10129, pp. 115-126, and "Utility Fog: the stuff dreams are made of", www.nanotech.rutgers.edu/nanotech/Ufog.html
(2) W.McCarthy, "The Heart of (Programmable) Matter", www.scifi.com/sfw/Issues203/labnotes.html
(3) All my knowledge on Quantum Dot capabilities are from W. McCarthy, "Hacking Matter: Levitating Chairs, Quantum Mirages, and the Infinite Weirdness of Programmable Atoms, " 2003 Basic Books, New York, NY
(4) Ibid, pp. 15-19
(5) Ibid, pp. 143, "An individual quantum dot can produce light only at one specific frequency (color) which is determined by the energy levels of its trapped electrons."
(6) Ibid, pp. 16, "An when voltages are placed across them, they bring large number of electrons and electron-holes together at fixed energies, and thus have the interesting property of producing photons of very precise wavelengths. This means they can be used to make laser beams, including "surface emitting" lasers that can be fashioned directly onto the surface of a microchip."
(7) Ibid, pp. 53-54
(8) Ibid, pp. 103, direct quote
(9) Ibid, pp. 130
(10) Ibid, pp. 31, and G.J. Milburn, "Schrodinger's Machines: the Quantum Technology Reshaping Everyday Life", Freeman, New York, NY, pp. 105-113
(11) S. Wolfram, "A New Kind Of Science", 2002 Wolfram Media, Champaign, IL pp. 182-183, and 1193
(12) W. McCarthy, "Hacking Matter", pp. 127, for discussion on Quantum Dot size.
(13) Webster American Family Dictionary, pp. 614
(14) W. McCarthy, "Hacking Matter", pp. 104-108
(15) J. Martin, "After the Internet: Alien Intelligence", 2000, Capital Press, Washington DC, pp. 240
(16) Ibid, pp. 289-290
(17) W. McCarthy, "Hacking Matter", pp. 53-54
(18) Ibid, pp. 97, "...in some instances, the electrons don't occupy the atom in spin-up/spin-down pairs - most especially if the atom is large or asymmetrical. This behavior is complex and not well understood. Furthermore, any deviation from spherical symmetry will radically distort the shape and properties of the orbitals. the most extreme example is a perfect square or cubical quantum dot, in which the "orbitals" are linear tracks along which the electrons bounce back and forth. An electron traveling along the left-right axis would have no way to transition to the perpendicular sine waves. If one axis were much longer than the other, any light emitted by the dot would be highly polarized."
(19) G.J. Milburn, "Schrodinger's Machines." pp. 123-130