Peking University Research Breaks Ultra-Low Temperature Records to Map Complex Electronic Behaviors in Quantum Hall States

New research reaches 0.09 mK to map 100 fractional quantum Hall states, revealing a butterfly-shaped pattern in electron behavior and many-body interactions.

By: AXL Media

Published: Apr 29, 2026, 6:53 AM EDT

Source: Information for this report was sourced from EurekAlert!

Achieving Absolute Zero Extremes for Quantum Observation

The investigation of electronic organization in two dimensional spaces has reached a new pinnacle through the use of advanced nuclear adiabatic demagnetization. Researchers at Peking University successfully reached an environmental temperature of 0.09 mK, a current world record for cryogen-free refrigeration technology. This extreme thermal environment is essential because fractional quantum Hall states are notoriously fragile, appearing only when thermal fluctuations are almost entirely eliminated. By achieving these ultra-low temperatures, the team was able to stabilize and measure states that remain hidden in standard laboratory conditions.

Decoding the Butterfly Wing Pattern of Electron Organization

By utilizing high mobility gallium arsenide quantum wells provided by Princeton University, the research team identified a sophisticated geometric pattern in how electrons arrange themselves. When mapped using polar coordinates, where the angle represents the filling factor and the distance from the origin corresponds to the denominator of the fraction, the data forms a shape reminiscent of butterfly wings. This visual framework provides a systematic way to organize nearly 100 different states, offering a new level of clarity to a field of physics that has historically been defined by its immense complexity and theoretical density.

Validation of Composite Fermion Theory in Many Body Interactions

The study rigorously analyzed these observed states through the lens of composite fermion theory, which suggests that electrons in a magnetic field bind with quantized vortices to behave as non-interacting particles. The emerging "butterfly" pattern shows that most states cluster along the edges of the wings, indicating they are integer states of these composite fermions. However, the discovery of states within the interior of the wings suggests even deeper layers of fractionalization, occurring only when the interactions between the composite fermions themselves are taken into account.