Quantum Leap in Computing
Researchers in the field of computing are looking at the natural rotation of electrons, known as "spin," as holding a great deal of promise for the future of electronics. If scientists could figure a way to use spin to carry information, the ability of electronic components to process would increase several times their current output. Physicists in Dortmund, Washington, and St. Petersburg, have joined forces with those from the Ruhr Universistat Bochum with the result that the team was able to align the spin of an electron, bring it to "waver" point and obtain a read-out too. The scientists also discovered that the electron spin can be realigned as needed through the use of optical pulses.
Prof. Andreas Wieck, lead author of the study believes that this was a first, important step in understanding "quantum bits." This knowledge is bound to be integral to future systems relating to data transfer and processors. The results of the study have been published in Nature Physics.
The basis of modern electronics is electrical charges. A memory cell or bit that holds an electrical charge is represented by a "1." If the bit holds no charge, it is understood as "0."
But there's more to electrons than a charge. Electrons spin, too, in much the same way as a top, going around and around in their own axes. This produces a magnetic field, similar to that produced by the earth. An external magnetic field, applied to this spin can cause it to accelerate or decelerate. The top of the spin will begin to wobble. This is called "waver." Once waver is achieved, the axis can be tipped to a projected angle.
Being able to manipulate the spin in so many different ways opens up infinite possibilities were these variations capable of storing information. An electron would no longer be limited to 0 and 1. The possibilities are even greater when one takes into consideration the fact that other electrons could be positioned so as to exert force on other electrons in much the same way as two magnets on either side of a metal sheet. This would open a whole new field for data storage and processing. These little bits of information this new process can generate are called quantum bits or qubits. A small number of qubits can be used to calculate even very complicated computations. Those same computations, at the present time, would need millions of bits to perform.
A single electron has only a miniscule effect and it can be difficult to obtain electron measurements even with very sensitive implements. Because of this, the researchers concentrated on trapping one million electrons in indium-arsenic islands known as "quantum dots." In this way, the results become easy to measure, multiplied as they are by six, which makes for a stronger signal. Wieck comments that, "Contrary to the preconceptions of many international competitors, all associated electron spins exhibit precisely the same behavior and the microscopic effects can therefore be measured very easily."
The scientists also found they could rotate the aligned electron spin by using a laser pulse aimed at the desired angle. This action could then be read out through the means of another laser pulse. This is the first incidence of the manipulation of qubits. As Prof. Wieck commented, "The interesting factor here is that these electrons are enclosed in solid bodies, so we no longer need complex high vacuum equipment and light occlusion on all sides to keep them permanently in a module as in quantum optics."
The scientists at Bochum used the high vacuum a single time during the creation of the quantum dot. At this point, the semiconductor system gets sealed against air so that it has a long, reliable life.