A 100-Year-Old Physics Problem Has Been Solved

Resonant systems with high bandwidth.


Established in 1914, the fundamental principle of physics called the Lorentz reciprocity suppose an inversely proportional relationship between the length of time a wave could be stored to the bandwidth of resonant or waveguiding systems.

For more than 100 hundred years, the systems were held back by a physics problem. The length of time a wave could be stored was inversely proportional to its bandwidth. Any interpretation in this relation means it is impossible to store large amounts of data in resonant or waveguiding systems over a long period of time. It’s because increasing the bandwidth meant decreasing the storage time and quality of storage. And a small bandwidth means a limited range of frequencies (or ‘colors’) and therefore a limited amount of data.

Until now, this concept had never been challenged. But now, scientists working at the École Polytechnique Fédérale de Lausanne (EPFL) have successfully challenged this fundamental law. Scientists have discovered that more electromagnetic energy can be stored in waveguiding systems than previously thought.

While working around the fundamental law, they conceived resonant and waveguiding systems capable of storing energy over a prolonged period while keeping a broad bandwidth. By doing this, they have created asymmetric resonant or waveguiding systems using magnetic fields.

That means this physics problem is now a thing of the past. Now, scientists have developed a hybrid resonant/waveguiding system from a magneto-optic material. When a magnetic field applied on the material, it is able to stop the wave and store it for a prolonged period. Thus, it accumulates a large amount of energy.

Scientists noted, “With such systems, it is possible to store a wave for a very long period of time while also maintaining a large bandwidth.” Scientists even beat the conventional time-bandwidth limit. They then showed that there is no upper ceiling to this limit at all in such systems.

Kosmas Tsakmakidis, the study’s lead author said, “It was a moment of revelation when we discovered that these new structures did not feature any time-bandwidth restriction at all. These systems are unlike what we have all been accustomed to for decades, and possibly hundreds of years. Their superior wave-storage capacity performance could really be an enabler for a range of exciting applications in diverse contemporary and more traditional fields of research.”

According to scientists, this breakthrough could have a major impact on many fields of engineering and physics. It can be used in telecommunications, optical detection systems, and broadband energy harvesting.

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