New State of Matter Emerges at the Crossroads of Quantum Criticality and TopologyBy Steve Raines

Physicists have unveiled a groundbreaking quantum state of matter in a specially engineered quantum material, where strong electron interactions spontaneously generate topological properties at a quantum critical point. 

This discovery fuses two pillars of modern condensed matter physics—quantum criticality and electronic topology—into a unified phase that defies prior expectations, potentially enabling robust quantum devices for computing, sensing, and beyond.

Discovery Essentials

Researchers at TU Wien, collaborating with Rice University's Qimiao Si group, probed cerium-ruthenium-tin (CeRuSn) compounds near absolute zero, revealing an "emergent topological semimetal" where electrons lose particle-like quasiparticle identities yet organize topologically.  

Published January 14, 2026, in *Nature Physics*, the state arises as the material hovers between electronic phases, with quantum fluctuations knitting correlations and topology inseparably.  

Lei Chen's theoretical model at Rice confirmed that criticality itself induces topology, upending assumptions that strong interactions destroy such order.

Defining the "New State"

In quantum materials, states of matter denote phases defined by order parameters or topological invariants, akin to water's solid-liquid-gas transitions.  

Here, the phase manifests at a tunable quantum critical point, where thermal effects vanish and fluctuations dominate, yielding a topological organization without fixed band structures or quasiparticles.  

Dianair Schmittbaum at TU Wien noted the material "oscillates between two states, unable to decide," birthing this hybrid regime.

Material and Experimental Breakthrough

The quantum material involves strongly correlated electrons in CeRuSn, tuned via pressure or doping to the phase boundary.  

Ultra-low temperatures (near 0 Kelvin) and precise measurements exposed the state's signatures, validated by Rice's correlation-driven theory linking criticality to emergent band topology.  

This interplay—strong interactions generating topology—marks uncharted territory, as prior topological phases relied on non-interacting electron waves.

Technological Horizons

Correlation-driven topological states promise dissipation-free edge channels for spintronics, ultra-sensitive magnetometers, and topological quantum bits resilient to decoherence.  

Tunable via the critical point, the phase suits low-power switches between conventional and topological modes, ideal for space-hardened computing or precision sensors.  

Qimiao Si emphasized its practicality: "This is not mere theory; it advances technologies harnessing quantum principles."

Bridging Theory, Experiment, and Future Design

This work unites quantum criticality (fluctuating phases) with topology (wave-based order), expanding material engineering beyond band topology alone.  

Experiment-theory synergy, from TU Wien's probes to Rice's models, exemplifies how heterostructures and criticality unlock new phases.  

Looking ahead, systematic hunts for this state in known quantum-critical compounds could yield platforms for next-generation quantum tech, redefining matter's quantum playbook.