Light interacts with itself in the past tense in a new form of the double-slit experience

In a double slit experiment, light passes through two slits, separated by a small gap. The researchers have now performed this experiment with small gaps in time.

The famous double-slit experiment, which showed that light is both a wave and a particle, was performed using “slits in time”. The techniques used are a new way to manipulate light, and can be used to create exotic materials called time crystals.

Double slit experiment

In the double slit experiment, that is Thomas Young First conducted in 1801, you shone a beam of light onto a plate with two slits. As light waves pass through the slits, they interfere with each other, creating a pattern of light and dark lines on the screen behind them.

This is because you can think of light as a wave rippling through both slits. From each slit, a new circular wave pattern emerges, similar to what you see when you throw a rock into a pond. The tops and bottoms of the two wave patterns can cancel or reinforce each other. Where they reinforce each other, light stripes appear on the screen, as dark stripes cancel each other out.

This interference wouldn’t be possible if light was made up of particles. Therefore, this experiment was one of the first proofs that light is a wave.

split in time

Whereas the original experiment used two separate slits in a vacuum Richard Sapienza Imperial College London and colleagues kind of jellymeasurement experience Where the snags were separated slightly in time. This so-called time-wave manipulation is an old topic. But in the past 30 years it has been viewed mainly from a theoretical point of view. “It was very difficult to experiment, especially with light.”

This is because it requires materials that can change from transparent to reflective very quickly. This is necessary to create what the researchers call “splits in time”. Sapienza and his team used indium tin oxide, which is used in coating electronic displays. When a powerful laser beam hits this material, it goes from completely translucent to momentarily reflective.

To perform the experiment, the researchers used two successive pulses of a high-energy laser to make the material reflective while simultaneously shining less powerful light on it. probe-Laser. The light from the probe’s laser passed through the material when it was not being reflected, and then bounced back when it arrived at the same time as the strong laser pulse, so the material is reflected.

frequencies

When they measured the reflected light, the researchers found interference patterns similar to those in the classic version of the experiment. But this time it was the interference pattern in the light’s frequency that determined its color, not its brightness. “In Young’s experiment, light strikes the slit plate at one angle and exits from many different angles,” Sapienza says. “In our experience, light enters at one frequency and exits at different frequencies.”

The results of Sapienza and colleagues’ experiment behaved much as theoretical calculations predicted. The light’s frequency fluctuates, or oscillates, more than the researchers expected. The magnitude of the oscillations depends on the intensity of the material’s transition from transparent to reflective. This meant that the indium tin oxide responded to the laser pulses incredibly quickly: within a femtosecond (a femtosecond is a millionth of a billionth of a second).

“The material reacts 10 to 100 times faster than expected, which was a big surprise,” Sapienza says. “We were hoping to see some wobbles, and we’ve seen a lot.”

Telecommunications

This fast transition time can be useful for forming time crystals. These are special materials with moving structures whose movement is repeated over and over. But it can also help with more casual applications, he says Maxim Shcherbakov from the University of California, Irvine. Frequency interference is an exciting discovery that could have applications in many modern technologies. Particularly in telecommunications, where checking signals over time is very important.