Functional materials involving liquid/solid interfaces with novel properties derived from their meticulously designed structures have attracted considerable attention for their potential use in nanoelectronics, energy, and information science applications. However, controlling the functionalities of these materials has posed significant challenges for their implementation in real-world systems. The properties of nanomaterials including two-dimensional systems, nanoparticles, and self-assembled structures are largely influenced by interfacial phenomena that deviate from the intrinsic behaviors of their bulk counterparts. This leads to special electron interactions specific to the materials’ geometry and surface configuration, which dictate their functional properties. Among these materials, liquid/solid interfaces are ubiquitous in a variety of functional systems or being utilized in the form of molecular functionalization of the host materials as an efficient, non-invasive, and low-cost way to fine-tune material properties. Ionic liquids (ILs), a class of highly tunable compounds with superior robustness, provide an ideal platform to investigate the interactions with low-dimensional materials, particularly due to the charged nature of ILs and the highly controllable charge behaviors tailored by their ion structure and chemistry. These unique features make ILs particularly interesting systems for their interactions with the crystalline structures of low-dimensional solid materials. A major hurdle in fully leveraging these hybrid systems lies in the elusive nature of the liquid/solid interactions in highly confined regions and their roles in determining the systems’ properties. Our research group aim to utilize spectromicroscopy techniques with nanoscale lateral and depth resolutions to investigate these liquid/solid systems, shedding light on the chemical makeup, vibrational responses, and electron transition behaviors in highly confined space. These insights will enhance the fundamental understanding for advancing the design and implementation of liquid/solid layered systems in a variety of applications.

Gravitons are a central prediction of quantum gravity, yet their detection has long been thought impossible. We recently showed, however, that single gravitons can be detected using quantum sensing with macroscopic quantum resonators, conceptually analogous to the photoelectric detection of photons. In this talk, I will first give a brief overview of recent ideas for testing quantum signatures of gravity in table-top experiments. I will then turn to the detection of individual, on-shell gravitons, which represents a conceptually new approach. After revisiting the conventional arguments for the impossibility of graviton detection, I will present the key insights that overturn this view, explain the novelties that make detection feasible, and discuss why this possibility has been overlooked until now. Finally, I will show how such detectors could be implemented in the near future and how they go beyond mere particle detection: they are sensitive to the quantum statistical properties of gravitational radiation and enable tests of key predictions of linearized quantum gravity - echoing the first explorations of quantum theory in the early 20th century.
 

In the twentieth century, X-ray diffraction crystallography facilitated a breakthrough in materials science, allowing the determination of electron density and, hence, atomic positions from the angles and intensities of X-ray scattering. Later, in biocrystallography, this approach was extended to biological molecules. After crystallization, an electron density map can be constructed from X-ray diffraction data, and the molecular structure can be resolved. 

We have further extended the X-ray diffraction to whole living tissues without crystallization. The extracellular matrix (ECM), which is not crystalline per se, contains many elements that exhibit structural periodicities that can contribute to X-ray diffraction patterns, such as collagen, keratin, adipose tissue, and water. These ECM components can be altered by cancerous cells, and the resulting cancer-induced modifications can serve as structural biomarkers.

In this presentation, three possible implementations will be addressed. First, this approach can be applied to small samples from the pathological lab for fast classification, serving as a triage procedure for histopathology. We achieved excellent accuracy in distinguishing normal, benign, and malignant tissues. Second, it can be used for various animal models. I will report the revealing of cancer trajectories in mice with induced prostate or breast cancer. We have shown that cancer-induced alterations in the diffraction patterns can be observed not only in the affected organ but also in remote locations, such as the animal's skin. Another proxy organ for remote monitoring of the health status is the nails. We demonstrated that the nails of healthy and cancerous dogs can be distinguished with high accuracy. Recently, this approach has been extended to human samples. Finally, actual measurements of human patients to detect breast cancer are underway in our California lab.