Quantum computing
Imagine a computer whose memory is exponentially larger than its apparent physical size; a computer that can manipulate an exponential set of inputs simultaneously; a computer that calculates in the twilight zone of space. You would be thinking of a quantum computer. Relatively few and simple concepts from quantum mechanics are needed for quantum computers to be a possibility. The subtlety has been in learning to manipulate these concepts. Is such a computer an inevitability or will it be too difficult to build?
Based on the strange laws of quantum mechanics, Folger, the senior editor at Discover, points out that; an electron, proton or other subatomic particle is “in more than one place at a time”, because individual particles behave like waves, these different places are different states in which an atom can exist simultaneously.
What is the problem with quantum computing? Imagine that you are in a large office building and you had to retrieve a briefcase left on a randomly chosen desk in one of hundreds of offices. In the same way that you would have to walk through the building, opening the doors one at a time to find the briefcase, an ordinary computer has to fight its way through long strings of 1’s and 0’s to reach the answer. But what if instead of having to search for yourself, you could instantly create as many copies of yourself as there are rooms in the building? All copies could simultaneously spy on all offices, and whoever finds the briefcase becomes your real you. the rest just disappear. – (David Freeman, discover)
David Deutsch, a physicist at the University of Oxford, argued that it might be possible to build an extremely powerful computer based on this peculiar reality. In 1994, Peter Shor, a mathematician at AT&T Bell Laboratories in New Jersey, showed that, in theory at least, a full-blown quantum computer could factor even the largest numbers in seconds; an impossible achievement for even the fastest conventional computer. An outbreak of theories and discussions about the possibility of building a quantum computer is now permeating through the quantum fields of technology and research.
Its roots go back to 1981, when Richard Feynman pointed out that physicists always seem to run into computational problems when trying to simulate a system in which quantum mechanics would take place. Calculations involving the behavior of atoms, electrons, or photons require an immense amount of time in today’s computers. In 1985, in Oxford, England, the first description of how a quantum computer could work came from the theories of David Deutsch. The new device could not only out-speed today’s computers, but it could also perform some logical operations that conventional computers couldn’t.
This investigation began to look at the construction of a device and, with the go-ahead and additional funding from AT&T Bell Laboratories in Murray Hill, NJ, a new member was added to the team. Peter Shor made the discovery that quantum computing can greatly speed up the factoring of integers. It is more than just a step in microcomputer technology, it could offer insight into real-world applications such as cryptography.
“There is hope at the end of the tunnel that quantum computers will one day become a reality,” says Gilles Brassard of the University of Montreal. Quantum mechanics gives unexpected clarity in describing the behavior of atoms, electrons, and photons at the microscopic levels. Although this information is not applicable in everyday household uses, it certainly applies to all interactions of matter that we can see, the real benefits of this knowledge are only just beginning to show.
In our computers, circuit boards are designed so that a 1 or a 0 is represented by different amounts of electricity, the result of one possibility having no effect on the other. However, a problem arises when quantum theories are introduced, the results come from a single piece of hardware that exists in two separate realities and these realities overlap each other and affect both results at the same time. However, these problems can become one of the greatest strengths of the new computer, if it is possible to program the results in such a way that the undesirable effects cancel out while the positive ones reinforce each other.
This quantum system must be able to program the equation into it, verify its calculation, and extract the results. Researchers have examined several possible systems, one of which involves using electrons, atoms or ions trapped within magnetic fields, then crossing lasers would be used to excite confined particles to the correct wavelength and a second time. to restore the particles. to its fundamental state. A sequence of pulses could be used to arrange the particles in a usable pattern in our system of equations.
Another possibility from MIT’s Seth Lloyd proposed the use of organic-metallic polymers (one-dimensional molecules made of repeating atoms). The energy states of a given atom would be determined by its interaction with neighboring atoms in the chain. The laser pulses could be used to send signals along the polymer chain and the two ends would create two unique energy states.
A third proposal was to replace organic molecules with crystals in which information would be stored in the crystals at specific frequencies that could be processed with additional pulses. Atomic nuclei, rotating in either of the two states (clockwise or counterclockwise) could be programmed with the tip of an atomic microscope, either “reading” their surface or altering it, which of course would be “writing” part of the storage of information. “Repetitive movements of the tip, eventually you could write any desired logic circuit,” DiVincenzo said.
However, this power comes at a price, as these states would have to remain completely isolated from everything, including a missing photon. These outside influences would build up, causing the system to drift off track and could even turn around and end up backtracking, leading to frequent errors. To prevent this from forming new theories have emerged to overcome this. One way is to keep the calculations relatively short to reduce the chances of error, another would be to restore redundant copies of the information on separate machines and take the average (mode) of the responses.
This would undoubtedly give up any advantage for the quantum computer, which is why AT&T Bell Laboratories has invented an error correction method in which the quantum bit of data would be encoded into one of nine quantum bits. If one of the nine were lost, then it would be possible to recover the data from the information that was transmitted. This would be the protected position the quantum state would enter before being transmitted. Also, since the states of atoms exist in two states, if one were to be corrupted, the state of the atom could be determined simply by looking at the opposite end of the atom, since each side contains the exact opposite polarity.
The gates that would transmit the information is what today’s researchers primarily focus on, this single quantum logic gate and its arrangement of components to perform a particular operation. One of those gates could handle the change from 1 to 0 and vice versa, while another could take two bits and make the result 0 if both are equal, 1 if they are different.
These gates would be rows of ions held in a magnetic trap or individual atoms that pass through microwave cavities. This single gate could be built within a year or two, but a logic computer must have millions of gates to be practical. NYU’s Tycho Sleator and UIA’s Harald Weinfurter see the gates of quantum logic as simple steps in making a quantum logic network.
These networks would not be more than rows of doors interacting with each other. The laser beams shining on the ions cause a transition from one quantum state to another, which can alter the kind of collective motion possible in the matrix, and therefore specific light frequencies could be used to control interactions between the elements. ions. A name given to these matrices has been called “quantum dot matrices” because the individual electrons would be limited to the structures of quantum dots, encoding information to perform mathematical operations from simple addition to factorization of those integers.
The “quantum dot” structures would build on advances in the manufacture of microscopic semiconductor boxes, the walls of which keep electrons confined to the small region of the material, another way to control how information is processed. Craig Lent, the principal investigator on the project, bases this on a unit consisting of five quantum dots, one in the center and four, and at the ends of a square, the electrons would be tunnelled between either site.
Putting them together would create the logic circuits that the new quantum computer would require. The distance would be enough to create “binary cables” made up of rows of these units, flipping the state at one end causing a chain reaction to flip all the states of the units down along the cable, just like current dominoes. they transmit inertia. Speculation about the impact of such technology has been debated and dreamed of for years.
In the discussion points, the point that its potential damage could be that the computational speed could thwart any security attempts, especially the NSA data encryption standard would now be useless as the algorithm would be a trivial problem for such a machine. . In the last part, this dream reality first appeared on the television show Quantum Leap, where this technology becomes evident when Ziggy, the hybrid parallel computer that he has designed and programmed, is mentioned, the capabilities of a quantum computer reflect the of the program’s hybrid computer.