Physicists measure superfluid stiffness in magic angle graphene successfully

Physicists have made a crucial measurement of superfluid stiffness in “magic-angle” graphene. This material exhibits exceptional properties, including unconventional superconductivity, when two or more atomically thin graphene sheets are twisted at a precise angle. This property allows electrons to pair up and move through the material with zero friction, making it a promising building block for future quantum-computing devices.

By developing a new experimental method, researchers at MIT and Harvard University have directly measured superfluid stiffness in magic-angle graphene for the first time, revealing that its superconductivity is primarily governed by quantum geometry, which refers to the conceptual “shape” of quantum states that can exist in a given material. The findings, reported in the journal Nature, provide valuable insights into the mechanism of superconductivity in this two-dimensional material and pave the way for further research into the properties of magic-angle graphene and its potential applications in quantum computing and other fields.

The article discusses a breakthrough in measuring the superfluid stiffness of magic-angle twisted bilayer graphene (MATBG), a two-dimensional material that exhibits superconducting properties. Researchers at MIT, led by Professor Jarillo-Herrero, have developed a new approach to measure superfluid stiffness in MATBG using a microwave resonator.

The team faced significant challenges due to the delicate nature of MATBG, which is only a few atoms thick. To overcome these challenges, they used techniques developed by Professor Will Oliver’s group at MIT to connect the MATBG sample to the microwave resonator with minimal loss of signal.

The researchers found that the superfluid stiffness of MATBG was much larger than predicted by conventional theories of superconductivity. They attribute this surplus to the material’s quantum geometry, which refers to how the quantum states of electrons correlate.

The study has significant implications for our understanding of superconducting materials and their potential applications in quantum computing and other fields. The researchers believe that their approach can be used to investigate other strongly interacting condensed matter systems, and they are already exploring its application to different materials, such as magic-angle twisted trilayer graphene (MATTG).