Scientists have added a dozen new “species” to the growing “quantum zoo” — a term researchers use to describe the countless strange states that matter can take at the quantum level.
In a new study published in Nature, a team led by Columbia University found over a dozen new quantum states, some of which could be key ingredients for building future quantum computers.
Quantum matter behaves in ways that seem strange and counterintuitive.
For decades, many of the predicted quantum states were purely theoretical, hidden in the math but never seen in real materials. Now, thanks to advanced experiments, researchers are finally starting to find them.
Lead author Xiaoyang Zhu said the team didn’t expect to see so many new states.
Some of these newly discovered states could eventually help scientists create topological quantum computers — a new type of quantum computer that would be much more stable and resistant to errors compared to today’s machines.
Current quantum computers use superconducting materials, which are sensitive to magnets and prone to mistakes. The states discovered by Zhu’s team, however, don’t need an external magnet at all. Instead, they arise naturally in a special material called twisted molybdenum ditelluride.
This discovery connects back to the Hall effect, first found in 1879. In the classical Hall effect, electrons moving through a metal strip bunch up along one side when exposed to a magnetic field.
At ultra-cold temperatures and in two dimensions, the Hall effect behaves differently — electrons’ behavior becomes “quantized,” jumping in specific steps.
Even more oddly, groups of electrons can behave as if they carry a fraction of an electron’s charge, a phenomenon called the fractional quantum Hall effect, which earned Columbia Professor Horst Stormer a Nobel Prize in 1998.
Last year, physicist Xiaodong Xu and his team found a version of this effect in twisted molybdenum ditelluride — but without needing an external magnet. Building on that work, Zhu’s team used a special laser technique, called pump-probe spectroscopy, to uncover many more fractional states in the same material.
They even found energy signatures related to rare and much-hunted particles called non-Abelian anyons, which could be essential for topological quantum computing.
Postdoctoral researcher Yiping Wang and Simons Fellow Eric Arsenault played key roles in developing the technique that made this discovery possible. Their method is so sensitive it can detect the tiniest differences between dozens of quantum states.
Now, the challenge is to figure out exactly what these new quantum states are and how they might be used. But one thing is clear: the quantum zoo just got a lot bigger and much more exciting.
