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Scientists are continuing to discover new ways to integrate quantum physics into our daily lives. A research group in the (IQST) is working on an exciting new application of the foundational working principle of quantum physics — quantum entanglement, an increasingly understood phenomenon that has no counterpart in classical physics.

Dr. , PhD, is an assistant professor in the , recently joining ��ݮ����Ƶ���� from the Institute of Science and Technology Austria (IST Austria). With his ��ݮ����Ƶ���� research group, , Barzanjeh plans to continue exciting new research he began at IST Austria, where his team invented a new radar prototype that uses quantum entanglement to detect objects.

in the journal Science Advances.

Quantum-based detection technology sharpens radar capabilities

Quantum entanglement is a physical phenomenon where two particles remain interconnected, and share physical traits regardless of how far apart they are from one another.

As part of his work at IST Austria, Barzanjeh was part of a group of research collaborators who harnessed quantum entanglement to create a prototype using a new, quantum-based radar detection technology. Barzanjeh, who conceived and conducted the original experiment, worked alongside Dr. Johannes Fink, PhD, of IST Austria, and collaborators from Massachusetts Institute of Technology (MIT), the University of York, and University of Camerino.

A radar receiver becomes less sensitive, and therefore less accurate, when it picks up too much noise — random, usually unwanted signals. Dubbed “microwave quantum illumination,” the device prototype uses entangled microwave photons (generated cryogenically at a temperature of -273 Celsius) as a method of detection. Known as a ‘quantum radar’, it is able to detect objects in “noisy” thermal environments, giving it an advantage over more classical radar systems.

“We were able to use entanglement, in practice, to improve radar sensitivity,” Barzanjeh explains.

This increased sensitivity is achieved by comparing two groups of entangled photons, called the ‘signal’ and ‘idler’ photons. The ‘signal’ photons are sent out toward an object, while the 'idler’ photons are measured in relative isolation, away from interference and noise. When the signal photons are reflected from the object, a small amount of quantum correlation between the signal and idler photons survives. This correlation creates a signature or pattern that describes the existence or the absence of the target object. Comparing the differences in noise between the original ‘idler’ photons and the reflected ‘signal’ photons will reveal the presence of the targeted object.

“Practically, we compare the existence and absence of the correlation between signal and idler,” Barzanjeh explains. “In presence of the target, we catch the idler-signal correlation, while in the absence of the target, the correlation is zero.”

Potential impact on health care, security industries

Proof of the feasibility of ‘quantum radar’ represents one of the most significant changes to radar technology in decades. While Barzanjeh says the technology is in the very initial stages, it could have a number of potential applications in different areas, such as biomedical and security.

This radar could be used for improved MRIs, for detecting certain cancers, or for implanted sensors to detect results quickly and accurately. “This is a short-range radar and has a number of limitations due to the special cryogenic conditions we need to generate the entangled photons,” he explains. “But the technology could work very well for short-range applications like detecting biological samples.”

Barzanjeh will work with his research group at ��ݮ����Ƶ���� to further explore applications of microwave quantum sensing.

“I’m focused on finding a new road for this research, and mapping it in that direction,” he says.

Integrated Quantum Hybrid Circuits is an interdisciplinary (experimental and theoretical) research group in IQST. Their research is focused on the reversible quantum interface between the superconducting circuits and quantum optical systems. They are interested in developing quantum communication technology that can be integrated with superconducting processors for building large-scale quantum networks.