1. Superconducting computer
The higher the integration of the chip, the smaller the size of the computer, so that the speed of the whole machine will not be reduced because of signal transmission. But this will cause the machine to heat up seriously. The solution to the problem is to develop superconducting computers.
When the current flows through the superconductor, the resistance is zero and the medium does not generate heat. 1962, the British physicist Josephson put forward the "superconducting tunneling effect", that is, a device composed of superconductor-insulator-superconductor (Josephson device). When a voltage is applied across the device, electrons will pass through the insulating medium unimpeded like a tunnel, forming a tiny current, and the voltage drop across the device is almost zero. Compared with traditional semiconductor computers, the power consumption of superconducting computers using Josephson devices is only a few thousandths, but the time required to execute an instruction is 100 times faster.
1999165438+1October, Japan Institute of Superconducting Technology cooperated with enterprises to produce a superconducting integrated circuit chip consisting of 10000 Josephson elements. It is reported that the institute plans to produce this superconducting chip in 2003 and this superconducting computer in about 20 10.
2. Nanocomputers
On the nanometer scale, due to quantum effect, silicon microelectronic chips can't work. The reason is that the work of this chip is based on the overall characteristics of solid materials, that is, the statistical average law when a large number of electrons participate in the work. If the quantum effect of finite electron motion is used on the nanometer scale, the above difficulties may be overcome. Nano-scale calculation can be achieved through different principles. At present, four working mechanisms are proposed: 1) electronic nano-computing technology; 2) Nanocomputers based on biochemical substances and DNA; three
) mechanical nano computer; 4) Coherent calculation of quantum waves. They may develop into the basis of future nano-computer technology.
3. Optical computer
Different from traditional silicon chip computers, optical computers use light beams instead of electrons to calculate and store: different data are represented by light with different wavelengths, and data are transmitted from one chip to another by a large number of lenses, prisms and mirrors. As early as the late 1950s, people put forward the idea of developing optical computers. From 65438 to 0986, David Miller of Bell Laboratories successfully developed a small optical switch, which provided the necessary components for Allen Huang in the same laboratory to develop an optical processor. 1990 65438+ 10, Huang's laboratory began to work with a full computer. Optical computers have all-optical type and photoelectric hybrid type. The above-mentioned optical computer of Bell Laboratories adopts a hybrid structure. In contrast, all-optical computers can achieve higher operation speed. To develop an optical computer, it is necessary to develop an optical "transistor" that can control the change of another beam of light with one beam of light. The existing optical "transistor" is huge and clumsy. If it is used to make a desktop computer, it will be as big as a car. Therefore, it is still difficult to make the optical computer practical in a short time.
4.DNA computer
1994165438+1October, Dr. Adlerman of the University of Southern California, USA, used the DNA base pair sequence as the carrier of information coding, and made the DNA base pair sequence react under the action of control enzymes in a test tube to realize data operation. Adlerman published the theory of DNA computer in the journal Science, which attracted wide attention from scholars all over the world. Adlerman's computer calculation is different from the traditional computer. Calculation is no longer just simple addition and subtraction of physical properties, but also adds various ways of cutting, copying, pasting, inserting and deleting chemical properties.
The biggest advantage of DNA computer lies in its amazing storage capacity and operation speed: 1 cubic centimeter of DNA stores more information than one trillion optical disks; More than ten hours of DNA calculation is equivalent to the total amount of calculation since the advent of all computers. More importantly, its energy consumption is very low, only one tenth of that of electronic computers.
Unlike the traditional "tangible" computer, the current DNA computer is still a liquid lying in a test tube. It is far from development and practical application, and there are still many practical technical problems to be solved. For example, the difficulty of biological operation, sometimes slight oscillation will break DNA; Some DNA will stick to the test tube wall and tip, thus losing prediction in calculation. It will take 10 to 20 years for DNA computers to enter the practical stage.
5. Quantum computer
Quantum computer uses atoms in quantum state as central processor and memory, and uses the quantum characteristics of atoms to process information. Because atoms are in two different positions at the same time, that is, the atoms in qubits can represent 0, 1, and the intermediate values between 0 and 1 and between 0 and 1, so the ability of qubits is twice that of transistors in data storage and processing. In this regard, someone has made such a metaphor: suppose a mouse wants to bypass a cat. According to classical physics theory, it passes either from the left or from the right, while according to quantum theory, it can bypass the left and right sides of the cat at the same time.
A quantum computer is very different in appearance because it has no box-shaped shell. It looks like a huge magnetic field, surrounded by other substances; It can't realize the long-term storage of information with hard disk; However, the efficient computing power makes quantum computers have broad application prospects.
There are many schemes to realize quantum computing, but the problem is that it is really too difficult to manipulate micro quantum States in experiments. These computers are extremely sensitive, and even the smallest interference, such as the passing cosmic rays, will change the direction of calculating atoms in the machine, leading to wrong results. At present, quantum computers can only do the simplest calculations with about five atoms. Millions of atoms must be used to do any meaningful work.
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