Quantum Photography

Physicists at EPFL announced arguably one of the most stunning photographs of all time, an image of light behaving as a particle and wave simultaneously. The whole premise of what they achieved is simply out of this world. The thought of managing to take an image of light itself to begin withis impressive.

To get an image of light the physicists directed lasers at a “nano”wire. We throw the word nano out all the time, but its helpful to have some perspective on what size we’re talking about here. When we talk about small things we always use the archaic sheet of paper, but that’s way too thick and is about 100,000 nanometers. Not helpful. As a better perspective of this scale, your finger nails grow about 1 nanometer every second. 3 gold atoms side by side would be nanometer.

The physicists pointed two laser beams at a wire on this nano scale. By carefully adjusting these lasers they were able to create what’s called a standing wave. This is where the two opposite waves appear to form a new third wave which stands completely still. There are plenty of examples of this with waves at our own scale. If you’re old enough to have been around with corded phones or slinkies, you absolutely made standing waves playing with those wires at some point.

Ok, but how on earth are they looking at this tiny nano wire to create this standing wave you ask? Fortunately the institution has access to one of the only two of these beauties on Earth, which allows them to visualize this tiny stream of light. Isn’t it adorable, with the very bottom of the microscope looking familiar with the two eyes and an adjusting gear, but everything else around it is straight out of a science fiction fantasy. And science fiction fantasy basically is what it achieves, with the ability to slow down and look at things the size of an atom vibrating.

By tuning this the lasers pointed at the nanowire, they were able to see this standing wave radiating inside the wire. This is a perfect image of light behaving as a wave, since we are observing light do something which we can observe waves do on our scale all the time. 

Despite the fact that we see this wave standing there, due to a hundred years of research, we also know that these waves are a effectively a stream of what we call photons, the particles which literally light up the universe. The physicists got tricky and started shooting a beam of electrons at the wire. These electrons interact with the photons, causing them to shift about. This is analogous to the break in a billiards game, our standard model of particle behavior.

The resulting effects are captured in this photo. What we are seeing is the standing wave effect caused by the wave nature of the photons; while simultaneously seeing individual points shifting off the wave due to the interactions with the stream of electrons which are caused by the particle nature of those same protons. This is likely the first photograph ever of the bizarre realities of quantum physics occurring before our eyes!

I know this stuff is dense, but hopefully you can see why I gave this photo such high praise at the start of the article. Here’s a short animated video to help visualize the experiment.