Joint Attosecond Science Laboratory

Understanding the behavior of strong-field photoelectron emission across different nanomaterials is essential for advancing ultrafast laser-matter studies. Here, the emission characteristics of diverse nanospheres, including metals, semiconductors, insulators, organics, and composite materials, are experimentally investigated using intense femtosecond lasers. Within the investigated strong-field range (24–100 TW/cm2), photoelectron emission shows minimal dependence on the nanomaterial type. In this regime, the cutoff energy increases gradually, approaching 10 times ponderomotive energy at 100 TW/cm2. The angular contrast of the emission decreases in magnitude with increasing laser intensity, yet its magnitude rises with increasing ellipticity of the polarization. An intensity-driven transition from backward- to forward-preferred emission is observed, dominated by rescattered electrons. An angular model for nanoplasmonic emission, Y(θ) = a|cos θ| + b, successfully reproduces the reconstructed angular distributions and yields a characteristic plasmon-enhancement parameter. Collectively, these findings establish a nanomaterial-independent strong-field regime in nanoscale targets and provide an empirically constrained angular model to facilitate interpretation and simulation of ultrafast laser-nanoparticle interactions.

Human biofluids serve as indicators of various physiological states, and recent advances in molecular profiling technologies hold great potential for enhancing clinical diagnostics. Leveraging recent developments in laser-based electric-field molecular fingerprinting, we assess its potential for in vitro diagnostics. In a proof-of-concept clinical study involving 2533 participants, we conducted randomized measurement campaigns to spectroscopically profile bulk venous blood plasma across lung, prostate, breast, and bladder cancer. Employing machine learning, we detected infrared signatures specific to therapy-naïve cancer states, distinguishing them from matched control individuals with a cross-validation ROC AUC of 0.88 for lung cancer and values ranging from 0.68 to 0.69 for the other three cancer entities. In an independent held-out test data set, designed to reflect different experimental conditions from those used during model training, we achieved a lung cancer detection ROC AUC of 0.81. Our study demonstrates that electric-field molecular fingerprinting is a robust technological framework broadly applicable to disease phenotyping under real-world conditions.

Abstract Recently we introduced a method to quantify the relative contribution of upfield versus downfield ionization when a diatomic molecule is exposed to intense infrared light [1]. Applying this to previously measured electron momenta distributions following strong field ionization of N2, we found approximately a 2∶1 ratio of electrons ionized from a downfield atom, relative to upfield. This suggests that the bound state wave function largely adapts adiabatically to the changing laser field, although the nonadiabatic process of ionization enhancement still contributes significantly even in neutral molecules. Here, we discuss the Quantum Trajectory Monte Carlo (QTMC) used to simulate electron trajectories, and explore possible modifications of the model [1].

Abstract Intense laser fields can reveal the attosecond and femtosecond response of matter in the emitted photoelectrons and high‐harmonic photons. The complementary perspective offered by these two messengers is well explored in gas molecules and, more recently, in bulk solids, where both electron emission and high‐order harmonics have been utilized to probe the laser‐matter interaction. In nanoscale solids, electron emission provides a wealth of information about the localized and inhomogeneous near fields around the nanoparticles. Here, it is shown experimentally that inhomogeneous fields also affect high‐order harmonics. Specifically, the experiment reveals strong indications that the field gradient of a nanoscale plasmonic hotspot found inside a Si crystal induces the emission of even‐order high harmonics from the crystal itself. This demonstration extends the complementary electron‐photon perspective on attosecond science to nanoscale systems.

As a contribution to the new field of WaterHCI (Water-Human-Computer Interfaces), we proposed and developed a smart SUP (Stand-Up Paddleboard) to assist a person with a disability (shoulder + back injury) to continue paddling and cross-country swimming (pulling a paddleboard to carry cargo while swimming). The paddleboard technology consists of two thrusters (motorized propellers) driven (1) in proportion to the flex of a paddle, to maintain the same feeling as normal paddling but with easement on shoulder strain, or (2) in proportion to the tension of a tow line attached to a waist strap around a swimmer’s waist. We also propose a controller for controlling a throttle using paddle flex or the tension of a pull cord. We also propose the use of our throttle control technology in transporting the paddleboard by way of a pulled wagon or an electric cargo bicycle (loaded up with the paddleboard and related supplies), at times when it is necessary to push it up steep hill. The wagon has a pull cord similar to the paddleboard, and the bicycle consists of a handlebar equipped with force sensors to provide the similar effect to pulling the paddleboard or wagon.

Different hypotheses of carcinogenesis have been proposed based on local genetic factors and physiologic mechanisms. It is assumed that changes in the metric invariants of a biologic system (BS) determine the general mechanisms of cancer development. Numerous pieces of data demonstrate the existence of three invariant feedback patterns of BS: negative feedback (NFB), positive feedback (PFB) and reciprocal links (RL). These base patterns represent basis elements of a Lie algebra sl(2,R) and an imaginary part of coquaternion. Considering coquaternion as a model of a functional core of a BS, in this work a new geometric approach has been introduced. Based on this approach, conditions of the system are identified with the points of three families of hypersurfaces in R42: hyperboloids of one sheet, hyperboloids of two sheets and double cones. The obtained results also demonstrated the correspondence of an indefinite metric of coquaternion quadratic form with negative and positive entropy contributions of the base elements to the energy level of the system. From that, it can be further concluded that the anabolic states of the system will correspond to the points of a hyperboloid of one sheet, whereas catabolic conditions correspond to the points of a hyperboloid of two sheets. Equilibrium states will lie in a double cone. Physiologically anabolic and catabolic states dominate intermittently oscillating around the equilibrium. Deterioration of base elements increases positive entropy and causes domination of catabolic states, which is the main metabolic determinant of cancer. Based on these observations and the geometric representation of a BS’s behavior, it was shown that conditions related to cancer metabolic malfunction will have a tendency to remain inside the double cone.

We explore the use of the SWIM (Sequential Wave Imprinting Machine) to visualize and photograph electric motor voltages and currents plotted as a function of position in a way that also captures the effects of a vehicle, vessel, (con)veyance, or vironment's drivetrain, or the like, as well as other effects such as wheel, propeller, or paddle slippage. We explore SWIM as an eXtended Reality (XR) for safety. Whereas an oscilloscope can show these voltages and currents as functions of time, our use of SWIM shows them as functions of space, situated in visual reality, i.e. as an augmented reality (AR) or extended reality (XR) that can be photographed or viewed by the human eye without the wearing of any special eyeglass or headset. Whereas previous work on SWIM typically uses rotary SWIM to visualize or photograph rotary phenomena (e.g. the behaviour of an electric motor) and linear SWIM to visualize or photograph linear phenomena, in this paper we propose and demonstrate the use of linear SWIM to capture rotary phenomena, such as the combined effect of a rotary electric motor on vehicle/vessel/veyance/vironment propulsion.

In this work we use helium ion beam nanolithography to structure the surface of an MgO crystal and control the emission of extreme-ultraviolet high harmonics. We demonstrate their focusing to below 300 nm in waist diameter.

We generate circularly polarized high harmonics from solids by matching the laser’s three-fold symmetries with those of the crystal. The chiral harmonic radiation probes the ferromagnetic surface states formed in magnesium oxide by spontaneous chiral-symmetry-breaking.

We demonstrate that high-harmonics generation (HHG) in metallic titanium nitride outperforms HHG in conventional metals limited by the damage threshold. Metal harmonics can link solid and plasma HHG together, and pave way for XUV generating plasmonics.