News: Research

The Nagel group introduced a new class of pluripotent metamaterials: trainable liquid crystal elastomer (LCE) metamaterials with a surprisingly beneficial trait—the ability to forget. Their article in PNAS describes how, after training LCE arrays to exhibit one behavior, their team was then able to “reset” the material using heat, so it could be retrained for different behaviors.

The Jerison & Dinner groups have developed a new tool for the identification and discovery of different types of dynamical behavior in a range of complex systems. In their recent publication in PRX Life, they train neural networks to infer the topology of dynamical flows from trajectory data by using contrastive learning on coordinate-invariant representations.

The Vaikuntanathan group found that biophysical systems have intrinsic limitations on their information processing power and explained how these limitations are overcome. Their article in Nature Communications uses tools from non-equilibrium statistical mechanics to demonstrate both the intrinsic limitations and how input multiplicity—behaviors such as the ability of enzymes to interact with multiple targets—can overcome them.

In response to a series of puzzling observations of light-induced "superconductivity" discovered by A. Cavalleri, the Levin group showed that the materials in which he found this phenomenon all seem to be strongly paired superconductors but in their normal state (above Tc). Their article in npj Quantum Materials explains his experiments by discussing how radiation exposure causes the preformed pairs in these materials to become more plentiful as the damaging fermions are excited away. The light creates a new state of matter, showing diamagnetic signatures without true superconducting long-range order.

The Alivisatos & Engel groups introduced a mechanism for the efficient up-conversion observed in CsPbBr₃ lead halide perovskite nanocrystals. Their paper in Nature Communications discusses how they used photoluminescence measurements to reveal that the up-conversion is mediated by the Pb-Br-Pb bending phonon mode (~7 meV) and involves unexpected coherent lattice motion synchronized with exciton-polaron formation.

The Littlewood group introduced a general classical linear field theory for non-reciprocal interactions. Their article in Physical Review E demonstrates how non-reciprocity can, surprisingly, enhance stability, while instabilities occur at Critical Exceptional Points.

The Guyot-Sionnest group designed highly sensitive quantum dot photoconductors with optical enhancement. Their publication in ACS Nano discusses how they used a HgTe quantum dot film to create photoconductors with a ~20-fold improvement in long-wave infrared detectivity.

The Tian group introduced a hydrogel derived from the malva nut with multiple biomedical applications, from wound care to ECG readings. Their publication in Matter discusses the sustainable extraction process used isolate the nut’s polysaccharides and demonstrates its enhanced performance in biosignal recording and tissue regeneration.

The Vitelli Group designed a compound robot which use principles of odd elasticity and active materials to enable decentralized locomotion across challenging terrains. Their paper in Nature explains how each part exerts nonsymmetric and nonreciprocal forces to create a robust collective machine that senses and responds to its environment.
 

The Delacrétaz group asks, is there a quantum limit to how fast many-body systems can equilibrate? Their publication in Nature Physics shows that large hydrodynamic fluctuations prevent a wide class of systems from regaining thermal equilibrium faster than the "Planckian time scale", set by Planck's constant and the equilibrium temperature.

The Talapin group designed a method of directly synthesizing various III-V quantum dots using a molten inorganic salt environment. Their paper in JACS demonstrates how this thermally-stable, oxygen-free environment enables the formation of highly crystalline InGaP and GaP nanocrystals.

The Murugan group discovered that physical systems can efficiently perform complex computations with contrastive learning. Their paper in Nature Communications shows how simple systems can use integral feedback to solve problems without digital hardware.

The Park group introduced a way to control the spectral response and light polarization of organic crystals just one atom thick. In their Nano Letters article, they synthesize spectrally similar molecular crystals in different 2D lattices in order to tune their optical properties.

An Engel group article in the Journal of Physical Chemistry Letters describes unexpected behavior observed in electrons passing through a conical intersection. They found the final electronic population had drastically different vibrational coherences from those it started with, a first-of-its-kind observation that is  unexplained by the semiclassical theory on conical intersections.

The Scherer group introduced a method of calculating the entropy production rate of overdamped, non-conservative, N-body systems. Their article in Physical Review E uses a novel collective mode decomposition and force field decomposition to show that the rates of entropy production and power dissipation are equal in these systems, in agreement with a theorem by Seifert.