Scientists may have gotten a step closer to creating the world's first quantum computer by successfully linking two different quantum systems to one another.
The researchers found "teamwork" in the world of quanta could lead to breakthroughs in quantum computing. Quantum dots (qDots) can disseminate quantum information extremely quickly, but often forget the equation just as fast, the University of Bonn reported. Charged atoms (ions) on the other hand have extremely efficient memories that can store quantum information for minutes, which is an "eternity" in the quantum world. Despite their memory powers, ions' internal processes are significantly slower than qDots'. The combination of these two components creates a "hybrid system" that bring quantum computers closer to reality.
qDots are believed to be the "great hopes" in the development of quantum computers, they can be thought of as "miniaturized electron storage units." These units can be easily produced in the same way as conventional computer chips, but are then miniaturized until they hold only one electron that can take on states predicted by quantum theory. The problem is these states are extremely short-lived and decay within only a few picoseconds. The decay releases a small flash of light, or photon, that vibrates on a specific direction of polarization that is determined by the qDot's state.
"We used the photon to excite an ion," said Professor Dr. Michael Köhl from the Institute of Physics at the University of Bonn. "Then we stored the direction of polarization of the photon."
In order to do this the researchers connected a thin glass fiber to the qDot and transported the photon to the ion through that fiber. To make this transfer as efficient as possible the researchers trapped the ion between two mirrors, causing the photon to be bounced back and forth like a "Ping-Pong ball" until it was absorbed by the ion. This could allow the qDot to be preserved in the ion for up to minutes.
"By shooting it with a laser beam, we were able to read out the ion that was excited in this way," Köhl said. "In the process, we were able to measure the direction of polarization of the previously absorbed photon."
There appears to still be a long road ahead before quantum computing becomes applicable in the realy world, but this breakthrough brings us significantly closer.
"Researchers around the world are hoping for true marvels from this new type of computer: Certain tasks, such as the factoring of large numbers, should be child's play for such a computer. In contrast, conventional computers find this a really tough nut to crack. However, a quantum computer displays its talents only for such special tasks: For normal types of basic computations, it is pitifully slow," the researchers stated.
The findings were published in a recent edition of the journal Physical Review Letters. Researchers from the University of Cambridge also contributed to the findings.
