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As humans venture deeper into space, the need for a lunar settlement, housing the first group of settlers, grows steadily. By means of new technologies such as in situ resource utilisation (ISRU) as well as computational design, this goal can be implemented in present years. Providing the first arrivals with an immediate underground habitat safe from radiation and other environmental constraints is of crucial importance to initialise a prolonged mission on the Moon. The project's proposal revolves around the idea of establishing a base which provides an immediately habitable space with the possibility for future expansion. Advanced construction methods and sustainable practices lay the groundwork for a permanent human presence, predominantly based on ISRU. This paper outlines a two-phase initiative aimed at the foundation of the Lunar Subterra, followed by an extension of the habitat above ground. Following our collaboration with the PoliSpace Sparc Student Association group, a Virtual Reality (VR) reproduction of the proposed habitat enabled quick iterative testing of the habitable space with the use of a Meta Quest 2 headset. This not only allowed an evaluation of the environment and its impact on human residents but also eradicated the need for tangible models to conceptualise the idea, enabling rapid user-centred design and implementation in the future of space exploration., Comment: 75th International Astronautical Congress (IAC), Milan, Italy, 14-18 October 2024

A ferroelectric material often exhibits a soft transvers optical (TO) phonon mode which governs it phase transition. Charge coupling to this ferroelectric soft mode may further mediate emergent physical properties, including superconductivity and defect tolerance. However, direct experimental evidence for such coupling is scarce. Here we show that a photo-launched coherent phonon couples strongly to electronic transitions across the bandgap in the van der Waals (vdW) two-dimensional (2D) ferroelectric semiconductor NbOI2. Using terahertz time-domain spectroscopy and first-principles calculations, we identify this mode as the TO phonon responsible for ferroelectric order. This exclusive coupling occurs only with above-gap electronic transition and is absent in the valence band as revealed by resonant inelastic X-ray scattering. Our findings suggest a new role of the soft TO phonon mode in electronic and optical properties of ferroelectric semiconductors., Comment: 18 pages, 5 figures, 13 pages SI

Excitons are fundamental excitations that govern the optical properties of semiconductors. Interacting excitons can lead to various emergent phases of matter and large nonlinear optical responses. In most semiconductors, excitons interact via exchange interaction or phase space filling. Correlated materials that host excitons coupled to other degrees of freedom offer hitherto unexplored pathways for controlling these interactions. Here, we demonstrate magnon-mediated excitonic interactions in CrSBr, an antiferromagnetic semiconductor. This interaction manifests as the dependence of exciton energy on exciton density via a magnonic adjustment of the spin canting angle. Our study demonstrates the emergence of quasiparticle-mediated interactions in correlated quantum materials, leading to large nonlinear optical responses and potential device concepts such as magnon-mediated quantum transducers., Comment: 33 pages, 14 figures

Achieving precise control of photoinduced molecular charge transfer reactions underpins key emerging technologies. As such, the use of hybrid light-matter molecular exciton-polariton states has been proposed as a scheme to directly modify the efficiency and rate of such reactions. However, the efficacy of polariton-driven photochemistry remains an open question. Here, we demonstrate conditions under which photoinduced polaritonic charge transfer can be achieved and directly visualized using momentum resolved ultrafast spectroscopy. Key conditions for charge transfer are satisfied using Bloch surface wave polaritons, which exhibit favorable dispersion characteristics that permit the selective pumping of hybrid states with long lifetimes (100-400 fs) that permit vibrationally assisted molecular charge transfer. Using this approach, we tune the energetic driving force for charge separation, reducing it by as much as 0.5 eV compared to the bare exciton. These results establish that tunable and efficient polariton-driven molecular charge transfer is indeed possible using carefully considered photonic systems., Comment: 10 pages, 5 figures

Realizing lattices of exciton polariton condensates has been of much interest owing to the potential of such systems to realize analog Hamiltonian simulators and physical computing architectures. Prior work on polariton condensate lattices has primarily been on GaAs-based systems, with the recent advent of organic molecules and perovskite systems allowing room-temperature operation. However, in most of these room temperature systems, the lattices are defined using a bottom-up approach by patterning the bottom mirrors, significantly limiting the types of lattices and refractive index contrast that can be realized. Here, we report a direct write approach that uses a Focused Ion Beam (FIB) to etch 2D lattice into a planar microcavity. Such etching of the cavity allows for realizing high refractive index contrast lattices. We realize the polariton condensate lattice using the highly photostable host-guest Frenkel excitons of an organic dye small molecular ionic lattice (SMILES).1,2 The lattice structures are defined on a planar microcavity embedded with SMILES using FIB, allowing the realization of lattices with different geometries, including defect sites on demand. The band structure of the lattice and the emergence of condensation are imaged using momentum-resolved spectroscopy. The present approach allows us to study periodic, quasi-periodic, and disordered polariton condensate lattices at room temperature using a top-down approach without compromising on the quantum yield of the organic excitonic material embedded in the cavity.

Efficient matching of local image features is a fundamental task in many computer vision applications. However, the real-time performance of top matching algorithms is compromised in computationally limited devices, such as mobile phones or drones, due to the simplicity of their hardware and their finite energy supply. In this paper we introduce BEBLID, an efficient learned binary image descriptor. It improves our previous real-valued descriptor, BELID, making it both more efficient for matching and more accurate. To this end we use AdaBoost with an improved weak-learner training scheme that produces better local descriptions. Further, we binarize our descriptor by forcing all weak-learners to have the same weight in the strong learner combination and train it in an unbalanced data set to address the asymmetries arising in matching and retrieval tasks. In our experiments BEBLID achieves an accuracy close to SIFT and better computational efficiency than ORB, the fastest algorithm in the literature.

The manipulation of molecular excited state processes through strong coupling has attracted significant interest for its potential to provide precise control of photochemical phenomena. However, the key limiting factor for achieving this control has been the dark state problem, in which photoexcitation populates long-lived reservoir states with similar energies and dynamics to bare excitons. Here, we use a sensitive ultrafast transient reflection method with momentum and spectral resolution to achieve the selective excitation of organic exciton-polaritons in open photonic cavities. We show that the energy dispersions of these systems allow us to avoid the parasitic effect of reservoir states. Under phase-matching conditions, we observe the direct population and decay of polaritons on time scales of less than 100 fs and find that momentum scattering processes occur on even faster timescales. We establish that it is possible to overcome the dark state problem through careful design of strongly coupled systems.

Exciton-polaritons (EP), half-light half-matter quasiparticles that form in optical cavities, are attractive platforms for creating macroscopic coherent states like BECs. EPs based on organic molecules are of particular interest for realizing such states at room temperature while offering the promise of synthetic tunability. However, the demonstrations of such condensates have been limited to a few specific molecular systems1. Here we report a universal platform for realizing molecular polariton condensates using commercial dyes that solves long standing material challenges. This solution is made possible using a new and programable molecular material called small-molecule, ionic isolation lattices (SMILES) with the potential to incorporate a wide array of molecular fluorophores2. We show EP condensation in rhodamine by incorporating it into SMILES lattice placed in a planar microcavity. The SMILES approach overcomes the major drawbacks of organic molecular photophysical systems such as self-quenching, which sets the foundation for realizing practical polaritonic devices operating at ambient temperatures covering wide spectral range.

Latent Class Choice Models (LCCM) are extensions of discrete choice models (DCMs) that capture unobserved heterogeneity in the choice process by segmenting the population based on the assumption of preference similarities. We present a method of efficiently incorporating attitudinal indicators in the specification of LCCM, by introducing Artificial Neural Networks (ANN) to formulate latent variables constructs. This formulation overcomes structural equations in its capability of exploring the relationship between the attitudinal indicators and the decision choice, given the Machine Learning (ML) flexibility and power in capturing unobserved and complex behavioural features, such as attitudes and beliefs. All of this while still maintaining the consistency of the theoretical assumptions presented in the Generalized Random Utility model and the interpretability of the estimated parameters. We test our proposed framework for estimating a Car-Sharing (CS) service subscription choice with stated preference data from Copenhagen, Denmark. The results show that our proposed approach provides a complete and realistic segmentation, which helps design better policies., Comment: 25 pages, 8 figures

A major limitation of transient optical spectroscopy is that relatively high laser fluences are required to enable broadband, multichannel detection with acceptable signal-to-noise levels. Under typical experimental conditions, many condensed phase and nanoscale materials exhibit fluence-dependent dynamics, including higher-order effects such as carrier-carrier annihilation. With the proliferation of commercial laser systems, offering both high repetition rates and high pulse energies, has come new opportunities for high sensitivity pump-probe measurements at low pump fluences. However, experimental considerations needed to fully leverage the statistical advantage of these laser systems has not been fully described. Here we demonstrate a high repetition rate, broadband transient spectrometer capable of multichannel shot-to-shot detection at 90 kHz. Importantly, we find that several high-speed cameras exhibit a time-domain fixed pattern noise resulting from interleaved analog-to-digital converters that is particularly detrimental to the conventional "ON/OFF" modulation scheme used in pump-probe spectroscopy. Using a modified modulation and data processing scheme, we achieve a noise level of $10^{-5}$ OD for an integration time of four seconds, an order of magnitude lower than for commercial 1 kHz transient spectrometers. We leverage the high sensitivity of this system to measure the differential transmission of monolayer graphene at low pump fluence. We show that signals on the order of $10^{-6}$ OD can be measured, enabling a new data acquisition regime for low-dimensional materials.