Dutch researchers have developed a kind of quantum radio. The method could be used in astronomy or medicine, for example, or to study gravity.
The quantum chip is only 1 x 1 centimeter square
Photo: TU Delft
Everyone knows weak radio signals from everyday life: the favorite song on the radio suddenly turns into an unpleasant noise, or working on the living room table works not because the wireless router is in the other room and no viable connection to the Internet is established. In such a case, the user would consider installing, for example, a WLAN repeater to amplify the signal. The researchers at the Delft University of Technology have taken the opposite route. They have considered that it could make more sense to improve the recipient. For this they have developed an extremely sensitive circuit, which is actually a kind of quantum radion.
Avoid low-energy interference
Weak radio signals are annoying in some situations, others are real problem there. For example, they may ensure that the images of a magnetic resonance tomograph (MRI) fail. Or they make it difficult for scientists who want to investigate space with radio telescopes. In both cases, the new technology could become a support. The basic problem of weak signals lies in the photons themselves. They are very low in energy and therefore susceptible to disturbances, such as the ambient temperature. One approach, therefore, is to eliminate these perturbing photons by cooling the system down or, in other words, using a cold circuit.
The team led by Gary Steele and Mario Gely used a circuit normally called a resonator serves, so at certain frequencies – in this case 173 gigahertz – resonates. The basis is a Josephson system, in which two superconductors are separated by an insulator. The particles tunnel through the barrier from one superconductor to the other. The scientists cooled this circuit extremely low until most of the particles were at their lowest possible energy level (ground state).
Detecting the weakest signals in quantum mechanics
The scientists wanted to detect the weakest Signals that are possible in the theory of quantum mechanics – tiny quanta of energy. Mario Gely explains the principle: “Let’s say I push a child on the swing. If I want the child to fly a little higher in the classical theory of physics, I can give it a little push so it picks up more speed, which is nothing but energy. Quantum mechanics says otherwise: I can only increase the child’s energy by exactly one quantum step. It is not possible to perform the push half as much. “At the same time, these single quantum steps are so small that they would not be noticed by the child.
The same is true of radio waves. The research team in Delft, however, has succeeded with his circuit to filter out these smallest energy building blocks. Because in the extremely cooled circuit prevailed quantum physical conditions (jib condition). The researchers then completed the artificial cooling and then analyzed how the system dynamically interacted with its environment and, above all, the temperature, effectively measuring the quantum structure of the radio photons. They believe that these findings can be used to derive technologies that enable the development of novel radio telescopes or MRI. In the long term, their goal is even greater.
Experiments on quantum mechanics and gravity would be possible
One of the great puzzles of physics is gravitation, or the classification of gravity into the theories of quantum physics. “With our quantum radio we want to try to intercept the quantum vibrations of heavy objects, to control them and finally to experimentally explore what happens when we bring together quantum mechanics and gravity,” says Gely. “Such experiments are difficult, but if we succeed, we could test whether we can create a quantum overlay of space-time itself, a new concept that could validate our understanding of quantum mechanics and general relativity.”
Further contribution in the field of quantum mechanics:
- Researchers build tap-proof quantum repeaters