The weird world of quantum physics is being harnessed for some fascinating use cases. In the latest example, physicists have developed and demonstrated a “quantum radar” prototype that uses the quantum entanglement phenomenon to detect objects, a system which could eventually outperform conventional radar in some circumstances.
Quantum entanglement describes the bizarre state where two particles can become linked so tightly that they seem to communicate instantly, no matter how far apart they are. Measuring the state of one particle will instantly change the state of the other, hypothetically even if it’s on the other side of the universe. That implies that the information is moving faster than the speed of light, which is thought to be impossible – and yet, it’s clearly and measurably happening. The phenomenon even unnerved Einstein himself, who famously described it as “spooky action at a distance.”
While we still don’t entirely understand why or how it works, that’s not stopping scientists figuring out ways to use it to our advantage. Strides are being made towards creating quantum computers and a quantum internet, both of which would be super fast and nigh-unhackable. And now, in a new study by physicists at the Institute of Science and Technology Austria (IST Austria), MIT and the University of York, the phenomenon been applied to radar.
Radar works by sending out radio waves or microwaves, and then listening for how they bounce back to the receiver, which paints a clear picture of what objects are in the area. The new prototype system works on the same basic principle, but instead of radio waves it’s sending out photons.
First, pairs of photons are entangled. One of each pair is a “signal” photon, while the other is called an “idler.” The signal photons are the ones that are sent out towards the object of interest. The idlers, meanwhile, are kept in isolation, away from any interference. When the signal photon reflects back, it changes, which instantly affects the idler photon. And the device can then check the idler and determine whether a target object is present or absent in the area.
True quantum entanglement is lost between the two types of photons when the signal is reflected, but enough information is retained to create a signature that can determine a reading of an object.
While the process is fragile and very much experimental, the team says that the quantum radar is better than classical radar in some circumstances. For one, the new technique is more effective at picking a target object out of the background noise than low-power radar.
“What we have demonstrated is a proof of concept for Microwave Quantum Radar,” says Shabir Barzanjeh, lead author of the study. “Using entanglement generated at a few thousandths of a degree above absolute zero (-273.14 °C), we have been able to detect low reflectivity objects at room-temperature.”
Besides improving radar systems, the team says the new technology could also eventually be applied to security scanners and medical imaging of human tissue.
The research was published in the journal Science Advances.
Source: IST Austria
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