MIT’s new quantum device could make advanced radar and sensors work at room temperature

A novel hybrid and scalable device built by researchers at the Massachusetts Institute of Technology could power the next generation of radars and sensors using quantum technologies, while working at room temperature. This could open up new frontiers of advanced signal processing and secure communications without the requirement of bulky and expensive cooling equipment, typically associated with quantum technologies. Modern-day high-performance radar systems can detect extremely faint signals. The secret to this ability are microwave photons, the fundamental particles used in these systems. Using a device called a Josephson junction, scientists can split a microwave photon into two correlated photons, where one is used to encode a signal, while the other is used to decode it. Josephson junctions are part of superconducting circuits, which also find applications in secure communications networks. However, these superconducting circuits require temperatures below 273 degrees Celsius below zero (−459°F) to operate. This is possible only with cryostat machines, which are energy-intensive, bulky, and expensive. Working with magnets A research team led by Luqiao Liu, an associate professor at the Electrical Engineering and Computer Science Department at MIT, was pursuing other research interests when they realized that correlated microwave signals did not need cryogenically cooled superconducting circuits to be generated but could be achieved using magnets as well. The method to do so is relatively simple and requires a magnetic film to be placed in a microwave resonator. Using this device, the researchers split incoming microwave photons into a pair of synchronized signals with distinct frequencies. More importantly, they achieved this at room temperature. The device works using magnons, which are tiny packets of magnetic energy. When microwave photons are pumped into a magnetic system, they generate a pair of magnons with the same frequency, so the researchers must separate them: one can be used for signal transmission and the other for detection. Hybrid device The hybrid device built by the team allows the generation of hybrid magnon-photon waves, which have synchronized signals but with distinct microwave frequencies. The advantage of this approach is that an attacker intercepting the signal cannot decode it without having the matching frequency, which works as the key. “Magnonic systems exhibit a remarkably rich range of nonlinear dynamics, but these nonlinearities have not yet been harnessed for practical applications,” said Liu in a press release. “By using the level repulsion arising from coupling between magnons and microwave photons, we were able to separate the two magnons in frequency.” Their device could be used to build a noise-resilient communication system, where the receiver can decode a message, even though random data garbles it during transmission. Such microwave signals are also helpful in the operation of quantum simulators. These devices are being developed to carry out complex computations on subatomic particles and use them to predict new drugs and materials. Since these signals can be generated at room temperature, the approach is less expensive and scalable, making it more likely to be deployed in real-world scenarios. “This breakthrough will broadly impact secure microwave communications, hardware random number generation, correlation-based signal processing, and intelligent microwave sensing — all operating within the classical regime at room temperature,” said Can-Ming Hu, professor of physics and astronomy at the University of Manitoba in Canada, who was not involved in the work. “Looking ahead, this platform could well be remembered as the starting point for realizing quantum-inspired microwave sensing and communication technologies based on nonlinear cavity magnonics.” The research findings were published in the journal Nature Electronics. Get the latest in engineering, tech, space & science - delivered daily to your inbox.Ameya is a science writer based in Hyderabad, India. A Molecular Biologist at heart, he traded the micropipette to write about science during the pandemic and does not want to go back. He likes to write about genetics, microbes, technology, and public policy.