Magic Mirror on the wall, Who’s the Bubbliest One of All?

Faculty of Science
Professor Ebrahim Karimi and former postdoctoral fellow Dr. Mohammadreza Rezaee are overlooking a sonoluminescence quantum optics characterization setup.
You have probably heard of the famous Schrödinger’s Cat paradox — a thought experiment involving a hypothetical cat placed in a box with radioactive materials, where the cat is simultaneously dead and alive.

Schrödinger’s Cat is a great example of the complex and abstract nature of quantum physics, a field that explores the physics of the tiniest objects in the universe, such as electrons and photons.

Professor Ebrahim Karimi is a world leader in quantum physics. His research aims to understand the characteristics and distinctions between the Quantum and Classical worlds. His group recently made two new discoveries: the Quantum nature of Single-Bubble Sonoluminescence and the Flat Magic Window.

Sonoluminescence is a phenomenon in which an individual bubble is trapped in the centre of a liquid using sound waves, which are amplified to allow the bubble to expand and pop. As the bubble pops, it emits a bright blue light. The mechanism behind this phenomenon remained unknown until Prof. Karimi and former postdoctoral fellow Mohammadreza Rezaee solved the puzzle using their knowledge on the three types of light: laser, thermal and quantum. Each type is made up of photons that move in a certain pattern. “The photons act like soldiers”, says Prof. Karimi. In laser light, the soldiers are all moving together in a rigid and tight pattern, while in thermal light, they are all moving in different directions with no organized pattern. In quantum light, there is a gate that only allows one soldier to pass at a time. This behaviour of light is observed through a Sub-Poissonian distribution, which allowed Prof. Karimi to uncover that sonoluminescence is purely quantum light, meaning that when a bubble pops in a liquid, only one photon is emitted at a time. This discovery can be used to build a quantum source using bubbles.

The ’Flat Magic Window’ technique dates back to Ancient China and Japan. It involves a bronze mirror that appears completely flat to the naked eye, but when hit with direct sunlight, a hidden image “magically” appears projected on the floor or a screen, after reflection off the mirror’s surface. In the early 21st century, the physics behind this effect was revealed to be due to gentle variations to the surface of the mirror. Prof. Karimi and PhD student Felix Hufnagel recreated this magic mirror, but as a window and with liquid crystals — materials containing molecules that flow like a liquid but can also be arranged in patterns. They successfully created a slab of liquid crystals where instead of crafting the thickness, they crafted the orientation of the liquid crystals to create the desired hidden image. Their window also appears completely flat and transparent to the naked eye, until a light is shined onto it. This discovery can be used to further 3D projection imaging techniques, as this new method makes images look clear regardless of the distances and angles from which they are viewed.

Prof. Karimi recently earned an NSERC Arthur B. McDonald Fellowship, which is allowing him to dedicate more time to his research and achieve his goal of establishing Quantum Internet in Canada.

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