[ExI] Quantum Radar
avant at sollegro.com
Mon Sep 2 01:10:40 UTC 2019
Cool new tech: Quantum Radar. A team of scientists at the Institute of
Science and Technology in Austria just invented a cool new kind of
radar. It uses quantum entangled pairs of microwave photons to
drastically reduce the power consumption of radar and also makes radar
surveillance difficult to detect. This is one of the coolest practical
applications quantum entanglement that has been rendered into practice.
The device is simple in essence. The researchers create pairs of
entangled microwave photons using a superconducting device called a
Josephson parametric converter. They beam the first photon, called the
signal photon, toward the object of interest and listen for the
In the meantime, they store the second photon, called the idler
photon. When the reflection arrives, it interferes with this idler
photon, creating a signature that reveals how far the signal photon
has traveled. Voila—quantum radar!
This technique has some important advantages over conventional radar.
Ordinary radar works in a similar way but fails at low power levels
that involve small numbers of microwave photons. That’s because hot
objects in the environment emit microwaves of their own.
In a room temperature environment, this amounts to a background of
around 1,000 microwave photons at any instant, and these overwhelm the
returning echo. This is why radar systems use powerful transmitters.
Entangled photons overcome this problem. The signal and idler photons
are so similar that it is easy to filter out the effects of other
photons. So it becomes straightforward to detect the signal photon
when it returns.
Of course, entanglement is a fragile property of the quantum world,
and the process of reflection destroys it. Nevertheless, the
correlation between the signal and idler photons is still strong
enough to distinguish them from background noise.
This allows Barzanjeh and co to detect a room temperature object in a
room temperature environment with just a handful of photons, in a way
that is impossible to do with ordinary photons. “We generate entangled
fields using a Josephson parametric converter at millikelvin
temperatures to illuminate a room-temperature object at a distance of
1 meter in a proof of principle radar setup,” they say.
The researchers go on to compare their quantum radar with conventional
systems operating with similarly low numbers of photons and say it
significantly outperforms them, albeit only over relatively short
That’s interesting work revealing the significant potential of quantum
radar and a first application of microwave-based entanglement. But it
also shows the potential application of quantum illumination more
A big advantage is the low levels of electromagnetic radiation
required. “Our experiment shows the potential as a non-invasive
scanning method for biomedical applications, e.g., for imaging of
human tissues or non-destructive rotational spectroscopy of proteins,”
say Barzanjeh and co.
Then there is the obvious application as a stealthy radar that is
difficult for adversaries to detect over background noise. The
researchers say it could be useful for short-range low-power radar for
security applications in closed and populated environments.
Other applications come to mind such as detecting concealed weapons in
crowded environments without having to funnel people through a scanner.
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