Gaurav Chaudhary

In Plain English

In some ways, quantum condensed matter physics can be considered social sciences of electrons. Just as social sciences are studies of people and their societies as emergent collective behavior; the result of their interaction with each other and the environment, quantum condensed matter physics is the study of emergent phenomena when the countless electrons in a material interact with each other and their environment (temperature, electric and magnetic fields, atomic nuclei, the “topological environment”). Unlike social sciences, however, we know exactly what fundamental laws of nature the electrons follow when undergoing these social interactions. Simply put, it is simply quantum mechanics + electrodynamics. The main difficulty lies in solving these governing laws for an exponentially complex system and predicting new collective behavior.

Understanding these collective behaviors is crucial to answering questions like why magnets attract each other or how electricity can flow without any energy loss in some materials known as superconductors. Beyond answering these fundamental questions about nature, understanding the quantum mechanics of many electrons in solids has also led to the development of technologies such as silicon chips, magnetic memory, and MRI machines.

Indeed, the quantum mechanics of many interacting electrons in solids is extremely rich and often leads to phenomena that defy all our intuitions. For example, when electrons in topologically special environments interact, they can sometimes behave as if they are their own anti-particles or if they are only a fraction of an electron. If you are shocked to hear that, you are not alone. I was too! Most of my research to date is my efforts in overcoming this shock. Moreover, new technologies are emerging based on these shocking phenomena for a new quantum revolution, of which we have barely seen the beginning.

Clearly, if we can somehow control the environment and interactions of electrons, we can tune and find new quantum phenomena. Such control is “effectively” possible in newly discovered moiré materials, where a slight mismatch between two layers of material creates a “moiré modulation.” This modulation is similar to the musical beats produced by mixing sounds from different instruments. A key theme of my current research is exploiting the moiré modulation and performing calculations to predict new quantum phenomena in moiré materials.