APS Global Physics Summit student talks: Prasanna More, Abhishek Kumar, and Thomas Pétuaud-Létang

Colloidal Active Carpets for Spatiotemporal control over Microscopic Matter Transport

Speaker: Prasanna More

Authors: Prasanna T More, William Seavey, and Manasa Kandula

Active carpets, collection of active components on the surface, are ubiquitous in nature. Examples range from ciliary beds to sessile suspension feeders, generating cooperative hydrodynamic flows for nutrient capture. Even extracellular matrices dynamically regulate adhesion and sensing in real time. Emulating such behavior in synthetic systems offers transformative potential for lab-on-chip diagnostics, biosensing, and microparticle sorting. In this talk, I will present our work on synthetic active carpets, built using programmable dielectric matter. We show that dielectric colloids patterned on electrodes act as reconfigurable flow actuators under AC electric fields. By optically tuning the conductivity of the colloidal posts and designing their spatial arrangement on the electrode, we achieve spatiotemporally tunable electrokinetics for directed fluid transport. Our colloidal active carpets enable site-specific capture or release of diverse microparticles. Leveraging the universal electrokinetic response of microscopic particulate matter, we expect our platform to be broadly applicable for transporting microparticles like microplastics, bacteria, and vesicles.
__________________________________________________________

Learning Measurement-induced Phase Transitions Using Attention

Speaker: Abhishek Kumar

Authors: Hyejin Kim, Abhishek Kumar, Yiqing Zhou, Yichen Xu, Romain Vasseur, Eun-Ah Kim

In the monitored dynamics with entangling evolution subjected to mid-circuit measurements, a measurement-induced phase transition (MIPT) can be characterized by the learnability of quantum information extracted from the trajectories. The probabilistic nature of measurement makes it challenging to observe MIPT without relying on a non-scalable protocol, such as post-selecting measurement trajectories. We propose a post-selection-free approach that utilizes Quantum Attention Networks (QuAN) [1] to detect MIPT under generic Haar random unitaries and weak measurements. QuAN, which leverages the attention mechanism's power to drive large language models, is an efficient classical machinery to process measurement trajectories. QuAN is designed to access high-order moments of bit-string distribution while maintaining permutation invariance. We demonstrate that QuAN can witness MIPT, predicting the phase boundary that aligns with exact results. A sample complexity study highlights the potential for QuAN to learn MIPT from experimental data without post-selection, as it requires only a small number of samples readily accessible with current experimental platforms.
_________________________________________________________

Edge Superfluidity of He-4 Droplet on Graphite 

Speaker: Thomas Pétuaud-Létang

Authors: Thomas Pétuaud-Létang, Nikolay Prokof’ev, and Boris Svistunov

Based on the first-principles simulations by worm algorithm, we obtain compelling evidence of edge superfluidity in a droplet (as well as in an incomplete layer) of He-4 adsorbed on graphite. In the light of our results, the He-4 droplet on graphite and, possibly, on other substrates emerges as the experimental system of choice for a full-scale study of rich physics of edge superfluidity, including the regime of transverse quantum fluid.