Unraveling the Mystery of Strange Metals: Quantum Noise Experiments Shed Light on Unconventional Charge Flow

Researchers at Rice University uncover evidence challenging the conventional understanding of charge flow in strange metals

In a groundbreaking study published in Science, researchers at Rice University have conducted quantum noise experiments that provide new insights into the behavior of strange metals. These peculiar quantum materials have long puzzled scientists due to their unconventional properties. The study’s findings challenge the prevailing notion that charge flows through strange metals in the form of quantized packets of charge known as quasiparticles. Instead, the experiments suggest that charge moves collectively in a liquidlike form, defying traditional explanations. This discovery opens up new avenues for understanding the enigmatic nature of strange metals and may have broader implications for our understanding of quantum materials.

Strange Metals and Quantum Entanglement

Strange metals are a class of materials that exhibit unusual behavior at low temperatures. One such material, YbRh2Si2, was the focus of the study at Rice University. This quantum critical material undergoes a rapid transition from non-magnetic to magnetic when cooled below a critical temperature. At temperatures slightly above this threshold, YbRh2Si2 behaves as a “heavy fermion” metal, characterized by charge-carrying quasiparticles that are significantly more massive than bare electrons. These heavy fermions are the result of countless interactions between electrons in the material, forming discrete units of charge known as quasiparticles.

Challenging the Quasiparticle Picture

Previous theoretical studies have raised doubts about the nature of charge carriers in strange metals, suggesting that they may not be well-defined quasiparticles. To test this idea, the researchers at Rice University conducted shot noise experiments, which measure the fluctuations in quantum charge as it flows through a material. Shot noise experiments allow scientists to examine the granularity of charge carriers and determine whether they behave as discrete entities or in a more collective manner.

The results of the experiments on YbRh2Si2 were surprising. The researchers observed that the shot noise in strange metals was significantly suppressed compared to ordinary wires, indicating that charge moves in a more complex and liquidlike manner. This finding challenges the traditional understanding of charge flow in metals and raises questions about the nature of quasiparticles. It suggests that either quasiparticles are not well-defined entities or that they may not exist at all in strange metals.

Technical Challenges and Empirical Evidence

Performing shot noise experiments on YbRh2Si2 presented significant technical challenges. The researchers had to create nearly perfect crystalline films and fashion wires from these crystals that were thousands of times narrower than a human hair. Despite these challenges, the team successfully obtained empirical evidence supporting their hypothesis.

Implications and Future Directions

The implications of these findings extend beyond YbRh2Si2. The researchers are now exploring whether similar behavior arises in other compounds that exhibit strange metal behavior. This phenomenon of “strange metallicity” appears in various physical systems, regardless of their underlying microscopic physics. The linear-in-temperature resistivity characteristic of strange metals suggests the existence of a generic phenomenon that transcends specific materials.

The discovery of unconventional charge flow in strange metals opens up new avenues for research and challenges our understanding of quantum materials. By developing the right vocabulary to describe collective charge motion and exploring the underlying mechanisms, scientists may uncover a deeper understanding of the fundamental nature of these mysterious materials.


The recent quantum noise experiments conducted at Rice University have provided groundbreaking evidence challenging the conventional understanding of charge flow in strange metals. The suppressed shot noise observed in these materials suggests that charge moves collectively in a liquidlike form, rather than as discrete quasiparticles. This finding raises fundamental questions about the nature of quasiparticles and the underlying mechanisms of strange metals. The researchers’ discoveries pave the way for further investigations into the enigmatic behavior of strange metals and may have far-reaching implications for our understanding of quantum materials. As scientists continue to unravel the mysteries of strange metals, we inch closer to unlocking the secrets of the quantum world.






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