MADRID, March 21
First, the ability to manipulate and identify small quantities of interacting photons (light energy) with great precision has been demonstrated.
This unprecedented achievement represents a major milestone in the development of quantum technologies, according to scientists from the University of Sydney and Basel, who publish the breakthrough in Nature Physics.
Stimulated light emission, postulated by Einstein in 1916, is widely observed due to the large number of photons and laid the foundation for the invention of the laser. Inspired by this research, the emission of single photons has now been observed.
Specifically, the scientists were able to measure the near-time delay between a photon and a pair of bound photons scattering into a single quantum dot, an artificially created type of atom.
“This opens the door to engineering what we can call ‘quantum light,'” Dr Sahand Mahmoodian of the University of Sydney’s School of Physics and co-author of the research said in a statement.
Dr Mahmoodian said: “This fundamental science paves the way for advances in quantitative measurement techniques and photonic quantum computing.”
Noticing how light interacted with matter more than a century ago, scientists discovered that light was neither a beam of particles nor a wave form of energy, but rather exhibiting characteristics of both as a double wave of particles.
The way light interacts with matter continues to capture science and the human imagination, both for its speculative beauty and its powerful uses.
Whether it’s how light travels through the vast spaces of the interstellar medium or laser development, light research is a vital science with great practical uses. Without these theoretical foundations, almost all modern technologies would be impossible. No cell phones, no global communication network, no computers, no GPS, no modern medical imaging.
The advantage of using light in communication, through optical fiber, is that light energy, photons, do not easily interact with each other. This enables almost corruption free data transfer at the speed of light.
But sometimes we really want light. And this is where things get ugly.
For example, light is said to measure small changes in distance with instruments called interferometers. These measurement tools are now commonplace, either in advanced medical imaging, for important but perhaps more mundane tasks like controlling milk quality, or in the form of sophisticated instruments like LIGO, which first measured gravitational waves.
The laws of quantum mechanics place limits on the sensitivity of such reflections.
This value is set between how sensitive the measurement can be and the average number of photons in the measurement device. For classical laser light, this light is different.
Co-lead author Dr. Natasha Tomm from the University of Basel said in a statement: “We built a plot of such strong photon interactions that we could observe the difference between one photon interaction compared to two.” .
“We noticed that one photon stayed longer compared to two photons. When this photon-photon interaction is really strong, the two photons are entangled in a form of a bound state called a ‘photon.’
The advantage of this kind of light is that in principle, you can make sensitive measurements with better resolution by using fewer photons. This can be important for applications in biological microscopy where high light intensities can damage samples and where the features to be observed are particularly small.
“By demonstrating that we can identify and manipulate photon bound states, we have taken a critical first step in bringing quantum light to practical use,” said Dr. Mahmoodian.
“The next steps in my research are to see how to approach generating light statements that are useful for fault-tolerant quantum computing, which multi-billion dollar companies like PsiQuantum and Xanadu are pursuing.”
