The Durham Quantum Light and Matter (QLM) research section in the Physics department focuses on studying the quantum properties of atoms, molecules, and solids and their interactions with light. Our research includes both fundamental science and the development of quantum technologies that could benefit everyday life. Despite our varied research topics, we share some common themes:  

Matter  

Atoms make up everything around us and have existed since shortly after the Big Bang. Despite their importance, atoms are primarily composed of empty space. They have a core at the centre, which is extremely dense and tiny, made up of protons and neutrons. Surrounding the core, electrons are spread out at a considerable distance, whizzing around it.  If an atom were the size of a football stadium, the core would be about the size of a pea in the centre.   

Figure 1 - Click image to view video

Every atom is unique. Each element has a distinct number of protons in its core, and this is what makes each element different from others. The electrons in these atoms can exist in different energy levels – imagine these energy levels as rungs on a ladder (see Figure 1). Electrons can move up or down the ladder, but they need energy to move up, while they release energy when they move down. The higher up the ladder the electron moves, the more energy that is needed. When an atom absorbs or emits energy, its electrons don’t move smoothly from one energy level to another. Instead, they ‘jump’ from one level to another (see Figure 2).  

Figure 2 - Click image to view video

Magnetic, electric and optical fields can change the energy levels of atoms – like changing the distance between the rungs on a ladder (see Figure 3) – and it is for this reason why atoms are using in many technologies.   By studying the energy that atoms absorb or emit, scientists can determine the energy levels of atoms. Typically, the energy required to move between energy levels is in the form of light.  

Figure 3 - Click image to view video

Light  

Light makes up what is known as the electromagnetic spectrum. This spectrum includes not only the colours of the rainbow that we can see, but also types of light that are invisible to our eyes, such as infrared, radio waves, and X-rays.  Each colour or type of light carries a different amount of energy. For instance, X-rays are packed with more energy than the light we can see, and visible light carries more energy than radio waves. This energy can be transferred to other objects, affecting them in various ways.  

Click the image below to explore the electromagnetic spectrum!

Figure 4: The electromagnetic (EM) spectrum is the range of all types of electromagnetic radiation, varying by frequency and energy, including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.

Lasers are a unique type of light that allows us to interact with atoms at specific energy levels in a very controlled manner. This is why lasers are such an important tool in our labs in Durham. They help us unlock the secrets of the atomic world!  

Quantum  

Quantum mechanics, a branch of physics, helps us understand how light interacts with matter. It’s a bit like a mathematical recipe for the universe. One of the things we can do with this ‘recipe’ is use lasers to measure the energy levels in atoms very precisely.  Back to thinking of these energy levels like the rungs of a ladder. When we place atoms in an external field, such as a magnetic field (see Figure 3), it’s like giving the ladder a shake. The rungs move, and we can use lasers to measure how much they’ve moved. Atoms are incredibly sensitive to these ‘shakes’, which means we can also use these fields to adjust the energy levels exactly where we want them. This gives us a precise control over the state of the atoms.  

By studying quantum mechanics, we’re not just learning more about the fundamental principles of physics. We’re also finding ways to use this knowledge in new technologies. This has a wide range of practical applications that benefit society, from keeping time and guiding GPS systems, to creating detailed images and testing products, monitoring solar activity, and even developing quantum computers. It’s a fascinating field with endless possibilities!