Nobel Prize 2012: Seeing the Light

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Can We “See” Light? Before you answer this question with a yes, take a minute to ponder what “seeing the light” really means. You see light as a very tricky phenomenon. You probably know that we “experience” light by seeing it bounce off objects before being absorbed into our eyes. Obviously, without the light, our eyes are unable to see anything but darkness. Needless to say, we can also see light at its source—the Sun, light bulbs, flames, glow sticks; these are all visible to the naked eye.

So we can see the source, and we can see the point of reflection, but what about everything in-between? Can we see photons of light as they travel from their source to other objects?

Now that is the tough part. Normally we cannot see anything in-between; since in order to see light, it has to be absorbed, which consequently destroys it.

Solving this dilemma won Serge Haroche and David J. Wineland the Nobel Prize in Physics 2012.

These two scientists—who happen to be pioneers in quantum physics—worked out a way to not just “see” photons of light, but to trap and manipulate them as well. They were able to isolate individual photons and to study how they behave, without destroying them and without the complicated influence they have with the rest of the world.

Henry Reich from “Minute Physics” explains the science behind Haroche’s quantum experiment. For those of us who find physics particularly challenging, myself included, this video is very enlightening:

As we can see from the video, what he basically did was trapping a photon of light in a super dark, super cold cavity. This is particularly difficult since fundamental particles, such as photons, are difficult to isolate from their environment without destroying many of the mysterious quantum properties that make them interesting for physicists to study. Also, unlike atoms and ions, photons appear and disappear; they can be created and annihilated.

Wineland and Haroche independently invented ways to trap particles while maintaining their quantum properties. Wineland used electric fields to trap electrically-charged atoms, keeping them away from heat and radiation by conducting his experiments at very low temperatures and in a vacuum. Haroche trapped particles of light between superconducting mirrors that are cooled to a fraction above –273C, or absolute zero.

The cavity Haroche created contains two mirrors that face each other, and the trick was the very accurate mirrors, so that the light would be repeatedly reflected off each opposing surface. This arrangement allowed the photon to actually survive for a relatively long time, permitting scientists to study and manipulate it as they please.

Such experimental methods that enable measuring and manipulation of individual quantum systems are exciting because they could enable us to use quantum systems in many applications and in building new devices and future appliances. There is a lot to learn at the fundamental level, and discoveries based on those experiments have already been used to develop applications, such as ultra-accurate atomic clocks, and are expected to lead to the development of quantum computers that are much faster and more secure than existing electron-based technology.

References

www.guardian.co.uk
www.sixtysymbols.com

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