Scientists at the NIST (National Institute of Standards and Technology) have found a way to manipulate the properties of two electrically charged atoms simultaneously by entangling them using microwave technology. Till now, laser beams had been used for evaluating and entanglement of atoms. This entanglement phenomenon is considered so important because of the fact that it helps in error detection and correction in quantum computing. Quantum computing is regarded by many computer experts as the future of computers because of their unique ability to solve extremely difficult problems and algorithms that require a lot of combinations of solutions. Quantum computers that use the laser technology are really bulky with some of them large enough to occupy an entire room. However, this research breakthrough promises that the future devices using commercial microwave tech can be as small as smart phones.
The setup for the entanglement experiment at NIST
For many decades, microwaves have been used as carriers for mobile communication signals. They had also been successfully utilized for manipulating single atoms or ions. However, this is for the first time that the technology has been developed to tangle these electrically charged atoms by placing the microwave beams close enough (roughly 30 micrometers). This is a significant step towards data transportation and error correction in futuristic quantum computers. A paper related to this theory was published in the 11<sup>th</sup> August edition of the science journal <em>Nature. </em>In the experiment, the NIST physicists were able to condense the entire microwave source circuitry on a chip sized ion trap. The other equipments in the setup consisted desktop sized optic table, lenses, ultraviolet lasers for cooling, etc. The contraption was 10 times smaller than the previously used laser beam arrangement. The UV lasers used for cooling the ions will also be made smaller in the future. Thus, this technology is simpler and sleeker than the laser beam based quantum computers. Ions are considered to be the best candidates for being the basic memory unit for the quantum computing- the qubit.
"It's conceivable a modest-sized quantum computer could eventually look like a smart phone combined with a laser pointer-like device, while sophisticated machines might have an overall footprint comparable to a regular desktop PC," says NIST physicist Dietrich Leibfried, a co-author of the new paper.
"Although quantum computers are not thought of as convenience devices that everybody wants to carry around, they could use microwave electronics similar to what is used in smart phones. These components are well developed for a mass market to support innovation and reduce costs. The prospect excites us."
The aluminum nitride backed, gold electrode ion-trap chip
In this experiment, the electromagnetic fields were used to keep together the two ions that were lying above the ion trap chip. This chip was fabricated using aluminum nitride backing and had gold plated electrodes. The electrodes produced microwave oscillation pulses. The microwaves, having frequency in the range of 1-2 GHz, created the magnetic fields that caused the ions’ spin to rotate, making them resemble distinctly oriented bar magnets. This orientation is the basis of data representation in quantum computers.
The entanglement principal was the same as used by the NIST geeks in the laser beam approach. As the magnetic field due to the microwaves increases, the spins of ions get excited and if they are close enough, then they get entangled. . The properties of the entangled ions are linked, such that a measurement of one ion would reveal the state of the other.