Since the invention of the first monolithic integrated circuit by Jack Kilby of Texas Instruments in 1958, the integration of electronic components to improve even further the point that we now run hundreds of thousands of HP Pavilion DM4 components on the chip (chip) is only 1 cm 2, is ULSI (Ultra Large Scale Integration), which dethroned the VLSI today. In this scale circuits measure a fraction of a micron!
But this scale is the difficulty of producing worthy of a Mission Impossible. Not only quantum effects become apparent, but works much heat components, making it consume their lives. Circuits Finally, the solution is thus integrated mechanical stresses which can not be overcome.
To these difficulties, in 1982 invented the Nobel Prize in Physics, Richard Feynman, to overcome a quantum computer, a computer would be able to take advantage of quantum properties, particularly the stratification of the state.
Again, this is the Bell Laboratories, and discussed in particular Peter Shor invented an algorithm for factoring large numbers, convert them into products of simple factors. For example, the factorial of 5 = 120! = 5x4x3x2x1.
What is the relationship between the factorization and quantum computers? Cryptography! With this algorithm, a quantum HP G32 computer capable of the encryption codes most sophisticated to be broken in seconds!
Faced with this challenge that calculation a major interest of intelligence or military, hundreds of researchers worldwide have set a goal to set the first quantum computer in a few years. We went on the same day, a 2008 or 2020. The competition is open to your ideas!
How does a quantum computer?
We know that some classical HP G72 computer bits to present basic information that is processed one of two possible states: 0 or 1 This is the binary language.
0000, 0001, 0010, 0011, etc.: 4 bits are treated with a conventional computer, a state of less than 24 or 16 different states. In our example, the advantage of the quantum computer is capable of simultaneously processing 16 states.
We no longer live on the bits, but “Quantum” qubits to talk, have shown that for artistic illustration just above. Quantum computers with processors from N to 2 N different qubits can therefore manage the same information! Then N times faster than a classical computer to calculate, because they are in a position parallel to the implementation of these calculations! The number of qubits increases exponentially, so that the performance of parallel processes.
Today we are far from it, manage, how many states and most powerful HP Pavilion g4 quantum computers work best with seven qubits, the equivalent of a 7-bit processor but massively parallel. The advantage is obviously a very important moment backup. We will see that this technology has other advantages. But it also has some disadvantages.
Management of decoherence
We know it can be difficult, by the laws of quantum mechanics escapes control the behavior of a fuzzy logic that govern us are. A qubit has a consistent state, ie it shows the two possible states at once: it is quantum entanglement, or a nest. But if “decohere” the observable event, interact with the environment and falls into a classic of both countries.
This change in the quantum state is a major obstacle to making quantum computers, because it means that the potential power of these machines depends on the HP G62-100 properties of parallelism of the quantum state of the nesting.
Therefore, a fundamental question still remains unanswered: can we have a quantum computer, if you observe that the qubit decoherence know, is the cause? As the physicists say that a solution as difficult as cracking is a secret code!
Find the result
But this is not the only problem for physicists. A quantum computer operates in a multidimensional universe mathematically, the results of a calculation is performed in parallel in several parallel universes, or distributed. What is the practical consequence of this phenomenon?
As a holographic image, this means that the solution is a calculation from any interference from other results. In practice this means that if you see a certain result, which corresponds to an intermediate state occurs, no more interference will not occur, which stops, or rather the “crash” of the quantum computer .
As Young’s interference fringes, the results of quantum computing constructive and destructive interference, which could affect the observed results. The quantum results are specific to each algorithm, these differences can be used to compute the solution of a problem.
Avoid loss of information
Today one of the most important problems in computer science is the thermal design of components. Today, the temperature of the majority of Intel, AMD and Motorola is the fastest way quickly, the 80 ° C! Overheating when it is not cooled (vented or circulating oil bath) should be at the risk of “crash” the HP Pavilion g6 computer.
As in the computer room where the server, they must, if the ambient temperature exceeds 45 ° C, most of the computer should not be conditioned. It is the same for appliances (refrigerator, etc..)
The quantum computer presents a similar problem, although its origin is different. Physicists believe that quantum computers are not really limits, or computational speed and storage capacity or reliability, a leap forward on the current technology.
However, HP G62 there is another problem: no information during the calculation to lose. Physicists believe that will work as quickly as possible should come from the operations of a quantum computer is reversible: the input data must be drawn from these results. A calculation means irreversible loss of information used to determine the thermal effect, which may limit the performance of your computer are compared.
Consider an example with a logic circuit. An AND gate having two inputs to an output, so that a lost bit of information in the summation. We need a way to make some reversible logic gates and explore to find a method of control, so that information by a message of support of the sampling process (Shannon theorem) mediates reversible remains limited.
In 1976, Charles H. Bennett of IBM showed that it was possible to use a general purpose computer, the famous Turing machine, which use only with reversible doors. With the expression of a program in the form of primitive reversible operations, it turned out that the treatment was not significantly slower. This leads to the Toffoli gate, whose inputs are fully deductible travel.
The Church-Turing thesis
Before the implementation of a quantum computer HP Pavilion g6-1000, there are still many steps to the theory, to solve most of the approach of the concepts of cybernetics.
Among them, discovered in 1982, Richard Feynman, as they simulate a Turing machine, or rather copy the behavior of any physical object. He confirmed the Church-Turing thesis is: “. It can be programmed, or a general purpose computer in a way that all computing tasks can be performed by a physical object”
In 1984, David Albert has discovered that in the description of a quantum computer capable of measuring, the system is capable of the tasks of conventional computers can not simulate. His machine was able to buy their own subjective information, it is absolutely impossible that it should be measured from the outside world.
Finally, in 1989, was David Deutsch’s theoretical qubit is the greatest discovery to date. He proved that the computing power of a finite state machine with the laws of quantum computing in a single machine obeys the universal quantum computer were included. This HP Pavilion g7 computer is the corresponding quantum gates Toffoli, some additional helpers would be made so that a linear superposition of states 0 and 1, this machine can turn to a real quantum computer.
The discovery of English involves a slight change in the Church-Turing thesis: “There is, or you can make a universal quantum computer programmed to perform all the computing tasks of any physical object can be done. ”
The problem of consciousness
As interesting implications for quantum computing in the world of artificial intelligence. Since the advent of technology, some inventors have wanted to give their robots with artificial intelligence, or perhaps they were sentient on philosophical principles. From humble beginnings of the “animal machine” of Descartes, made great progress in developing artificial intelligence and robotics now be able, without fear of an imbalance or lack of energy. But these are not necessarily the cyborgs in science fiction of the bionic remain despite increasingly invade our daily lives.
If you look at the artificial creatures that look like NASA robonautes, P3, COG, or the AIBO dog, it is sometimes difficult to distinguish things, what, where, what programming of reflective consciousness and purchased .. . simulated. To see them react logically to ask irresponsible acts or look in the mirror now and then, if anything, these robots are not aware of something of himself. Its creator, at least like to believe. However, some people consider the human mind is capable of action can not be achieved through the implementation of a Turing machine. The debate is far from over.
In a quantum HP Pavilion g7-1000 computer , the problem of consciousness is a whole other dimension. Pressing the Church-Turing thesis, one must admit that any object, stone to the universe as a whole can be regarded as a quantum computer, and all identifiable physical processes may be the result of a calculation.
It can be argued that the human brain, computers and consciousness regarded as the result of calculation can be. The Church-Turing thesis, it allows us a very bold idea, but logical: since all computers are functionally equivalent and that a particular computer can simulate another, it must be possible to simulate consciousness, rational thinking, with using a quantum computer. And this can be itself be also the story of a lifetime of research.
If you think the engineers at MIT, or qubit, it is possible to solve the problem of artificial intelligence, thinks that some physicists like Roger Penrose of Oxford University, consciousness is so complex that it is much more exotic and physical stress is unknown. Decidedly, we are still far from solution. Despite trying a bit to go before the debate.
Production of a quantum computer (II)
Before considering the applications of quantum computers to see how we do it this way, a leap into the future.
Since a quantum computer manipulates qubits, whose preparation has nothing to do with that of a conventional computer, the processor runs at the transistor or a diode for example.
We have a new and high technology are the HP Omnibook 6000 qubits in superpositions of states 0 and 1 The way to do … does not exist, we are still experimenting with all the mistakes and successes of some fact that this step.
Today, there are several technologies:
- The laser and the quantum dot
- The computer NMR in solid
- The computer liquid or gas
- The semiconductor computer.
A., and quantum dot laser
To create a solution to a qubit, is a “quantum dot” which is essentially to develop an electron trapped in a cage made of atoms, the technical capacity now at Bell Labs and IBM, for example, atoms can be manipulated individually.
If this little “dot” illuminated by a laser pulse with a wavelength and a period of time, the electron goes into an excited state. A second laser pulse causes of falling to the ground state. The ground state and excited states of electrons are each 0 and 1 of a qubit, applying the laser beam on which a NAND function, wherein the change of state, 0 to 1 or 1 to 0 of the qubit.
When the laser pulse is shorter than half the time required for the NOT function, while the electron goes into a superposition of ground and excited states, it is the state of the qubit quantum nesting. More complex logic functions can be arranged in pairs with quantum dots. If this principle works in theory, create a good quantum puts quite a few difficulties that are preventing progress.
- The electron HP Pavilion G62 remains in its excited state is about 1 micro-second before he was in his stable. But the duration of a laser pulse is a thousand times shorter (1 ns). This technical problem currently limits the number of intermediate calculations before the information is lost.
- The construction of quantum dots is complicated by the minute because of their size. A quantum dot is only 10 atoms in length, one nanometer. Current computer technology does not develop these points.
- Adaptation measures Finally, to prevent thousands of lasers in a very small space, perhaps to allow the quantum dots of different light frequencies. Can emit a laser system, and lighting and various types of quantum dots. But here is the technology did not exist.
Like computers, solid, liquid or gaseous
MIT researchers to alternatives experiences of IBM and JPL to develop quantum dot quantum computer. Various techniques are atoms or molecules, or polarization of the laser light as information carrier. Again, the main HP Pavilion G42 problem is decoherence.
Attempts were made to protect the experience of the influence of the environment by cooling the sample to a thousandth of a degree above absolute zero, but these solutions are not entirely satisfactory.
The most interesting is a completely different approach. It is believed that the quantum medium must be isolated from the environment and very small businesses, information is stoquée in a sea of molecules. Exposed to a magnetic field rotates respectively basic molecules in a direction that its status: an illustrated spin provides a state, a spin 0, it is the principle by nuclear magnetic resonance (NMR), the output of the radio waves of certain detect changes to use spin.
How does an NMR system? Just as medical devices, instruments used in NMR quantum physics, superconducting magnets produce magnetic fields may be greater than 2 Tesla whole. The intensity is necessary because of the sensitivity of the HP Envy 17-1000 system increases with the intensity of the magnetic field. To examine the atomic and molecular structures, the RF fields emitted by about 500 to 750 MHz.
These magnets in a coil of wire in a dewar with liquid helium at -269 ° C, which are surrounded by a second Dewar of liquid nitrogen at -196 ° C submerged to eliminate these very low temperatures, the electrical resistance of the conductor and son getting very large current in the coil (30-90 A) without heat dissipation (Joule zero).
The advantage of this system is not energy is used to generate magnetic fields. The only restriction is replaced dozens of liters of liquid helium and at regular intervals to ensure that nitrogen superconductivity. Otherwise, loses coil increases and the system of its superconducting properties, the liquid evaporates probably due to damage of the HP G56 magnet.
A quantum computer technology using NMR reduced to a molecule, represented by the qubits these nuclei in the molecule. In fact, in the calculations, the system is not a single molecule, but a “soup” or a “cup” of liquid molecules. The advantage of this method is to avoid the risk of error, even when the liquid molecules to move to a different state, are the spin state of the nuclei in it unchanged. The problem of decoherence is present, but it seems much later than in any other technical maintenance to date. According to the results obtained in 2001 by Isaac Chuang of IBM Almaden Research Center, could be a few thousand primitive logical operations are performed before making décohèrent qubits.
The first results were obtained, and finally in 1998 by Isaac Chuang. With his team, he was fully able to create a quantum computer with two qubits in a thimbleful of chloroform and HP Pavilion g4-1000 was able to calculate the different periodicities of a function. He also managed to find a given 1-4 in one step by Grover’s algorithm.
The current work of researchers is more complex tasks that a larger number of qubits, so that the molecules increasingly necessary to achieve the nuclei. In 2001, Chuang and his team have succeeded in creating a system of seven qubits, which allowed them to perform the factorization of the number 15 with Shor’s algorithm. In practice, this means one billion billion molecules of control! That said the chloroform solution is unstable and its lifetime is limited to a few minutes.
Gershenfield Neil, director of MIT’s Media Lab is based on the caffeine molecules, a quantum computer would have to work with 10 qubits.
Chuang and Gershenfield that solutions of more than 15 or 20 qubits, since the magnetic signals indicative of the orientation of the spin quantum states and to measure low as to increase the number of qubits, the attenuation of a factor about 2 to each qubit.
Seeing the limits of NMR, Colin Williams of NASA JPL beat captures the attitude of the qubits in semiconductors and photons in optical resonators. The procedures for this are many: use of electrons in semiconductor materials, the flow of nuclei with other impurities in a semiconductor single-atom or HP Pavilion DV7-1000 electronic or magnetic flux in the superconducting environment is limited.
Whichever method you use, how we go beyond the manipulation of qubits? In theory, hundreds probalement, but never in organic solutions, but as a semiconductor. According to David Deutsch, a computer of 100 qubits could simulate the operation of an entire human brain. Remember that 100 billion neurons (1011), the digital equivalent of the brain manages approximately 21 011 possible states! The human brain has the best of 1015 and 10,000 synapses per cell contacts. This means that a quantum computer of 100 qubits could be the equivalent of 1,019 pieces of information processing in computer jargon or the equivalent of 10 000 teraflops of power! With about 300 qubits to simulate the Big Bang …
But realistically, with 7 qubits are still far from being able to design a quantum computer capable of competing with it was a handheld. In addition, the current prototypes are still very unstable.
Applications of quantum computers (III)
Suppose that our quantum computer is in use. If we make a calculation based on a classical algorithm on a quantum computer, the process will not run faster, no matter what. By what magic they can speed up the calculations, a quantum computer?
Any programmer knows that if such a multiplication calculation on a computer, an 8-bit encoding supported on the processor speed is programmed the same will not be quickly when run on a platform 32-bit. For faster results, they must re-compile the program for the new platform to participate in the benefits of the new 32-bit operations.
It’s the same with a quantum computer. For a quantum computer performs a task faster than a classical computer, we need to exploit the computational HP HSTNN-IB75 power of quantum parallelism. These algorithms are difficult to develop, and you can count on the fingers of one hand today, including Shor’s algorithm and Grover.
Well, if our programmers use one of these two algorithms on a quantum computer, I think it will not even have time to sit down to enjoy his surprise at the speed of their program. In fact, he was like a classical computer requires 10 million billion years to 1000 a number of figures factor. With Shor’s algorithm, our programmers will get the result … in 20 minutes!
A. The algorithms of Shor and Grover
Unfortunately, we do not describe algorithms Peter Shor and Lov Grover is beyond the scope of this article, but you will find enough information on the Internet, as they are now inseparable from the development of quantum computers.
Briefly say that the algorithm by Peter Shor in 1995, invented to account for a large number of rapidly enabled. It is mainly used in cryptography and probably find applications in public key encryption such as RSA (public key used to encrypt a message, while the private key can be decrypted).
Lov Grover algorithm (sorted), mainly to information in databases that are not indexed faster than a classical computer designed to look at.
It usually takes a survey N / 2, to find a record in a database with entries N Grover’s algorithm finds the data in a time √ N.
If the distributed databases are very large, the time gained is very valuable because the entire database in a variety of universes allows a search to find one of them the result. Grover’s algorithm is also used in cryptography.
B. Simulation of quantum systems
In 1982, Richard Feynman, one day it will be possible to use quantum computer quantum systems with much precision is more than ever possible to simulate, to do with conventional computers.
He imagined that a quantum computer and a few tens of qubits quantum simulations may need to try on classical computers because of the time it would take to implement necessary for the performance. This problem is purely technical, based on the fact that in a conventional computer, wherein the CPU and memory to simulate exponentially with the size of the HP HSTNN-DB75 quantum system.
On a classical computer, the dynamics of a quantum system in general by simulated approximations. Conversely, a quantum computer can be “programmed” to simulate the behavior of a system by deriving the interactions between variables, in this case mimics the properties of the system in question. Can a quantum computer, as the Hubbard model, the movement of electrons in a crystal, the simulation of a simulation is currently not being with a classical computer.
C. Quantum Communications
The development of quantum computing has created a new technology unexpected quantum communication. It is assumed that can be coded to the state of polarization of the photons (in the sense of its direction of oscillation) which is in each case with a direction of vibration quantum state 0 or 1. These two polarization modes are known, the linear mode (for specific vertical and horizontal polarizations) and the method of diagonal (bias from 45 to 135 °).
Data can be in the polarization of the photons to be coded. To receive or read data from the plane of polarization of the filter corresponds to that of photons. If the plane of polarization of the receiver is not correct, but it is a simple example, while the photon is transferred diagonally, the result is completely random and the message is unreadable. With this technique it is possible to avoid reading or listening to a HP HSTNN-DB72 message intrusive, which is kept secret.
In practice, will be a quantum transmission in several stages. The first, the transmitter sends the message regardless of the mode polarization. The receiver stores information with its random polarization.
The transmitter then sends the information to the receiver, it uses the polarization through a public channel. The receiver and transmitter then compare a random selection of the information received. If an officer stopped and the information presented, the sender and the recipient is informed by an error rate because it can be much higher than normal. In this case, the process will be repeated.
Thus, in a message with an estimated 50% of the correct reception, there are 50% of random information. Imagine a hacker intercepts the message and again at the receiver quantum. In fact, look at the message, its contents change, because it is a superposition of quantum states. It is therefore necessary to re-transmit, as if nothing had happened. Mistake, piracy is already registered? Let’s see why.
If half of the random information is in the best case, this means that 75% of the information by a third party, and could then be transferred back to be intercepted. If the noise is negligible on the line (0%), the pirates attempted to identify, because the information that the receiver in this case has received more than 25% error may be present. He sent this information by comparing a random selection of the HP HSTNN-IB20 message with the original message to the public sewer to be.
And if the attacker’s own message rather reflects the original, you might ask? The transmitter and receiver to discover when she passes the test, he will collect a set of random values. If an attacker has inserted his message, he will certainly be more similar to the original message. Although the attacker can make his message, the sender and the receiver will always find that their line was tapped.
Of course, the method only works when the noise is negligible on the transmission line. If the noise level, over 25% in our example, it is impossible to distinguish pirates ambient noise. Currently, such a system already exists. British Telecom is testing a quantum wire with the error of 9% over a distance of 10 km. Telecommunications piracy will soon be an old story!
The computer “liquid” invented by Dr. Chuang Gershenfield and allows us to envision a bright future quantum computer in the eye of the eye. They believe that may arise computer revolution in less than a generation, if progress continues at current rates.
The good news in these developments is that the problems of today, considered a technical problem, rather than fondamentaux.Demain perhaps a test tube with an organic solution, and a core electromagnet consists of computers quantum.
The most compact models will also be decorative items, sometimes sulphide office desktop. To celebrate, they are in the fruit juice or coffee.
If decoherence. Person, or Los Alamos, MIT, Princeton or IBM do not have a look at solutions for systems of more than 10 qubits that decoherence effect systems too fragile to be exploitable. Oh, when Richard Feynman was still with us, maybe he would have another of his big ideas …
However, we remain optimistic. Scavenging semiconductor qubits remains an area of research. Partial quantum computer can now communicate securely removed up to 10 km. Depending on the price that these lines costs and demand, it might be a good future for the quantum telecommunication.
If the conventional approach to slow computer limitations, quantum computers promises to her, giving us the performance and execution time will never be overcome. With it comes a whole new revolutionary computer theory, taking into account the effects of quantum mechanics and consider this act a physical object, like a quantum computer.
In this highly original, the quantum computer is theoretically able to simulate an infinite number of physical processes, and it can be in these circuits atomic secrets to the creation of hidden HP G62-130 computer with artificial intelligence.
Processing speed characterize, making quantum computers, the notion of parallel universe more tangible than ever. This power can only be achieved by using appropriate algorithms, but the theorists themselves, they will be extremely difficult to be released. Those we have invented already proven their skills in the world of cryptography in decoding codes to be untouchable for a classical computer.
The twenty-first century is undoubtedly that of information, information that is free of irony risk of piracy. Tomorrow, our network administrators and Dell Latitude D630 computer support of our teams to control quantum physics to help users and we will soon learn its basics in elementary school! Finally, preparatory courses in quantum physics to young students of Star Trek may not be as utopian as the …
Quantum laws that seem strange if we can help solve the problems with the more metaphysical science is now on the mind or the universe. As its means allow us to really understand the complex issues that no conventional computer can understand. Naturally remains to complete the program, which will probably be many years of hard work. But one day I hope we can quantum computers are questions that are now the responsibility of the philosophy that remain largely unanswered.
With such motivation, we can only encourage researchers who are engaged in this highway and we wish them a successful business.
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