Uncovering the Mysteries of Light
Scientists from the University of Sydney and the University of Basel have done something amazing – they figured out how to control and recognize extremely small amounts of light energy. This is an exciting breakthrough for creating quantum technologies. They published their study in a journal called Nature Physics on March 20.
In 1916, Einstein predicted something called stimulated light emission. Scientists have now witnessed this phenomenon with single photons and it’s what makes lasers work. They discovered this by measuring the amount of time it took for one photon to bounce off a special atom called a quantum dot.
Dr. Sahand Mahmoodian from the University of Sydney School of Physics said that this new discovery allows us to control something called “quantum light”. He also added that it will help in developing special techniques and computers based on quantum science.
A hundred years ago, scientists made a fascinating discovery – that light isn’t just particles or energy, but it’s both! It has what’s called wave-particle duality.
This incredible way light interacts with matter still excites scientists today, not only because of its beauty, but also due to its practical uses.
Research into light is really important, since it helps us understand things like how light moves through the stars in space. Without this research, modern technology wouldn’t exist – that includes your phone, Internet, computers, GPS and special medical machines for taking pictures inside your body.
Light is often used for sending messages because when photons, which are beams of light energy, travel through optic fibers, they don’t get mixed up with each other so information can be sent quickly and without distortion.
But sometimes we need the light to mix together. And this is difficult to do!
Light is used to measure small changes in distance with tools called interferometers. These measuring tools can be found doing cool things like medical imaging, or everyday tasks such as Milk Quality Control. One of the biggest uses of a interferometer was when LIGO measured the first gravitational waves back in 2015. However, according to Quantum Mechanics, there are limits to their sensitivity.
Scientists recently discovered an interesting limit between how well a measurement can detect something and how many particles are involved in the measuring device. This is different for light from lasers compared to quantum light.
Dr. Natasha Tomm from the University of Basel explained that their experiment was so accurate they could tell the difference when one particle interacts with the device versus two particles interacting with it.
We noticed that one photon took more time to move than two photons. This strong interaction between the two photons linked them together and created something called a “two-photon bound state”.
Quantum light has an advantage because it can measure things that are really small in a much better way and with fewer visible photons, which can be helpful for studying tiny elements under a microscope without damaging them.
Dr. Mahmoodian said that by showing how to spot and control a form of light called photon-bound states, we took an important first step in using quantum light for practical applications. The next steps for his research involve discovering if this same approach can be used to produce different forms of light which big companies like PsiQuantum and Xanadu are already spending millions to make use of nowadays.
Dr. Tomm said that this experiment is amazing because not only did it prove the effect of stimulated emission (this is like a light switch), but it was also a big breakthrough in further developing devices that trap photons. This technology could be used in biology, manufacturing and quantum information processing.
This is a research from scientists from four different universities: University of Basel, Leibniz University Hannover, the University of Sydney, and Ruhr University Bochum. It was published in a journal called Nature Physics on 20 March 2023. The topic was about how photons (light particles) can be used to form patterns and dynamics when a single artificial atom is present.
Two experts on this discovery, Dr. Natasha Tomm from the University of Basel and Dr. Sahand Mahmoodian at the University of Sydney, worked together to make it possible. The small particles called quantum dots were made in Bochum and used in experiments done at the University of Basel. Finally, Dr. Mahmoodian did some calculations on this study at the University of Sydney and Leibniz University Hannover.
This research is funded by some important organizations, like the Swiss National Science Foundation, Australian Research Council and German Ministry of Education and Research.
Reference: “A trusted node–free eight-user metropolitan quantum communication network” by Siddarth Koduru Joshi, Djeylan Aktas, Sören Wengerowsky, Martin Loncaric, Sebastian Philipp Neumann, Bo Liu, Thomas Scheidl, Guillermo Currás Lorenzo, Željko Samec, Laurent Kling, Alex Qiu, Mohsen Razavi, Mario Stipcevic, John G. Rarity and Rupert Ursin, 2 September 2020, Science Advances.
DOI: 10.1126/sciadv.aba0959
