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From ultraviolet to mid-infrared region, light-matter interaction mechanisms in semiconductors progressively shift from electronic transitions to phononic resonances and are affected by temperature. Here, we present a parallel temperature-dependent treatment of both electrons and phonons entirely from first principles, enabling the prediction of full-spectrum optical responses. At elevated temperatures, $\textit{ab initio}$ molecular dynamics is employed to find thermal perturbations to electronic structures and construct effective force constants describing potential landscape. Four-phonon scattering and phonon renormalization are included in an integrated manner in this approach. As a prototype ceramic material, cerium dioxide (CeO$_2$) is considered in this work. Our first-principles calculated refractive index of CeO$_2$ agrees well with measured data from literature and our own temperature-dependent ellipsometer experiment.

We present a numerical study on the super-resolution of quantum phase sensing and ghost imaging systems operating with multimode N00N states beyond the Rayleigh diffraction limit. Our computational simulations are based on the canonical quantization via numerical mode-decomposition (CQ-NMD) [1,2], in which normal (eigen) modes of electromagnetic fields in inhomogeneous dielectric media are numerically found using computational electromagnetics methods. In the CQ-NMD framework and the Heisenberg picture, the expectation value of arbitrary observables with respect to initial quantum states of various non-classical lights can be evaluated with the use of Wick's theorem. The present numerical framework has a great potential to deal with scattering problems of entangled photons due to arbitrary dielectric objects.

Phosphorylation is a prototypical example of post-translational modifications (PTMs) that dynamically modulate protein func-tion, where dysregulation is often implicated in disease. NMR provides information on the exact location and time course of PTMs with atomic resolution and under nearly physiological conditions, including inside living cells, but requires unambiguous prior assignment of affected NMR signals to individual atoms. Yet, existing methods for this task base on a global, hence, costly and tedious NMR signal assignment that may often fail, especially for large intrinsically disordered proteins (IDPs). Here we introduce a sensitive and robust method to rapidly obtain only the relevant local NMR signal assignment, based on a suite of FOcused SpectroscopY (FOSY) experiments that employ the long overlooked concept of selective polarisation transfer (SPT). We then demonstrate the efficiency of FOSY in identifying two phosphorylation sites of proline-dependent glycogen synthase kinase 3 beta (GSK3\b{eta}) in human Tau40, an IDP of 441 residues. Besides confirming the known target residue Ser404, the un-precedented spectral dispersion in FOSY disclosed for the first time that GSK3\b{eta} can also phosphorylate Ser409 without priming by other protein kinases. The new approach will benefit NMR studies of other PTMs and protein hotspots in general, including sites involved in molecular interactions and conformational changes

As several photovoltaic materials experimentally approach the Shockley-Queisser limit, there has been a growing interest in unconventional materials and approaches with the potential to cross this efficiency barrier. One such candidate is dark state protection induced by the dipole-dipole interaction between molecular excited states. This phenomenon has been shown to significantly reduce carrier recombination rate and enhance photon-to-current conversion, in elementary models consisting of few interacting chromophore centers. Atomically thin 2D transition metal di-chalcogenides (TMDCs) have shown great potential for use as ultra-thin photovoltaic materials in solar cells due to their favorable photon absorption and electronic transport properties. TMDC alloys exhibit tunable direct bandgaps and significant dipole moments. In this work, we introduce the dark state protection mechanism to a TMDC based photovoltaic system with pure tungsten diselenide (WSe2) as the acceptor material and the TMDC alloy tungsten sulfo-selenide (WSeS) as the donor material. Our numerical model demonstrates the first application of the dark state protection mechanism to a photovoltaic material with a photon current enhancement of up to 35% and an ideal photon-to-current efficiency exceeding the Shockley-Queisser limit.

Photovoltaic (PV) cells have become one of the most promising renewable energy technologies. To make PV more competitive with incumbent technologies, higher power output densities are needed. One promising approach is to add bifaciality to existing monofacial PV devices, allowing more output power from the additional reflection of sunlight from the ground (albedo). For example, bifaciality can be added to Silicon Heterojunction (SHJ) solar cell with Interdigitated Back Contacts (IBC) by opening up the gaps between the back metal contacts, but the optimum gap that maximizes power output is unknown. In this paper we show that that the optimum gap that maximizes IBC SHJ bifacial power output, where is the ratio of output power density to power loss due to shadowing and Joule heating, The results are validated by self consistent finite element device modeling. For a typical albedo factor of 0.3, an optimized bifacial IBC SHJ cell will produce 17% more power output than state-of-the-art monofacial IBC SHJ cells. The results encourage development of bifacial IBC solar cells as a next generation PV technology.

This work introduces a new software package `Sesame' for the numerical computation of classical semiconductor equations. It supports 1 and 2-dimensional systems and provides tools to easily implement extended defects such as grain boundaries or sample surfaces. Sesame has been designed to facilitate fast exploration of the system parameter space and to visualize local charge transport properties. Sesame is distributed as a Python package or as a standalone GUI application, and is available at https://pages.nist.gov/sesame/ ., Comment: 10 pages, 9 figures

The prospect of additional energy yield and improved reliability have increased commercial interest in bifacial solar modules. A number of recent publications have quantified the bifacial gain for several configurations. For example, a standalone, optimally-tilted bifacial panel placed over a flat ground (with 50% albedo) is expected to produce a bifacial energy gain of 30% (per module area). In contrast, for a panel array in a solar farm, self and mutual shading reduce the bifacial gain at the same tilt to 10-15% (per farm area). Bifacial gain is negligible for vertical arrays--although the configuration is of significant interest, since it can prevent soiling. Here, we calculate the bifacial gain of a solar farm where vertical arrays have been placed over sculpted/patterned ground. We conclude that vertical panels straddling (upward) triangle-shaped ground maximizes the energy output. For this optimum configuration, the bifacial gain can approach 50%, especially for regions with moderate to high cloudy conditions. The enhanced output, along with reduced soiling loss and lower cleaning cost of the ground sculpted vertical bifacial (GvBF) solar farm could be of significant technological interest, especially in regions such as the Middle East and North Africa (MENA), particularly susceptible to significant soiling losses., Comment: 7 pages, 4 figures

For commercial one-sun solar modules, up to 80% of the incoming sunlight may be dissipated as heat, potentially raising the temperature 20 C - 30 C higher than the ambient. In the long term, extreme self-heating erodes efficiency and shortens lifetime, thereby dramatically reducing the total energy output. Therefore, it is critically important to develop effective and practical (and preferably passive) cooling methods to reduce operating temperature of PV modules. In this paper, we explore two fundamental (but often overlooked) origins of PV self-heating, namely, sub-bandgap absorption and imperfect thermal radiation. The analysis suggests that we redesign the optical properties of the solar module to eliminate parasitic absorption (selective-spectral cooling) and enhance thermal emission (radiative cooling). Our Comprehensive opto-electro-thermal simulation shows that the proposed techniques would cool the one-sun and low-concentrated terrestrial solar modules up to 10 C and 20 C, respectively. This self-cooling would substantially extend the lifetime for solar modules, with The corresponding increase in energy yields and reduced LCOE., Comment: Discussion of low concentration PV is added

The Shockley-Queisser (S-Q) theory defines the thermodynamic upper limits for Jsc, Voc, FF, and efficiency of a solar cell. The classical calculation assumes an abrupt onset of absorption at the band-edge, perfect absorption for all energies above the bandgap, and absence of non-radiative recombination. These assumptions are never satisfied for any practical solar cell. In this paper, we explain how the S-Q limits are redefined in the presence of the non-ideal optical effects, and we provide closed-form analytical expressions for the new limits for Jsc, Voc, and FF. Remarkably, these new limits can be achieved to a very high degree, even with significantly imperfect materials., Comment: 5 pages, 6 figures, conference: 39th PVSC (2013)

We present highly robust, optimal control-based shaped pulses designed to replace all 90{\deg} and 180{\deg} hard pulses in a given pulse sequence for improved performance. Special attention was devoted to ensuring that the pulses can be simply substituted in a one-to-one fashion for the original hard pulses without any additional modification of the existing sequence. The set of four pulses for each nucleus therefore consists of 90{\deg} and 180{\deg} point-to-point (PP) and universal rotation (UR) pulses of identical duration. These 1 ms pulses provide uniform performance over resonance offsets of 20 kHz (1H) and 35 kHz (13C) and tolerate reasonably large radio frequency (RF) inhomogeneity/miscalibration of (+/-)15% (1H) and (+/-)10% (13C), making them especially suitable for NMR of small-to-medium-sized molecules (for which relaxation effects during the pulse are negligible) at an accessible and widely utilized spectrometer field strength of 600 MHz. The experimental performance of conventional hard-pulse sequences is shown to be greatly improved by incorporating the new pulses, each set referred to as the Fantastic Four (Fanta4)., Comment: 28 pages, 19 figures

Broadband inversion pulses that rotate all magnetization components 180 degrees about a given fixed axis are necessary for refocusing and mixing in high-resolution NMR spectroscopy. The relative merits of various methodologies for generating pulses suitable for broadband refocusing are considered. The de novo design of 180 degree universal rotation pulses using optimal control can provide improved performance compared to schemes which construct refocusing pulses as composites of existing pulses. The advantages of broadband universal rotation by optimized pulses (BURBOP) are most evident for pulse design that includes tolerance to RF inhomogeneity or miscalibration. We present new modifications of the optimal control algorithm that incorporate symmetry principles and relax conservative limits on peak RF pulse amplitude for short time periods that pose no threat to the probe. We apply them to generate a set of pulses suitable for widespread use in Carbon-13 spectroscopy on the majority of available probes.

We demonstrate the possibility of achieving enhanced frequency-selective near-field radiative heat transfer between patterned (photonic crystal) slabs at designable frequencies and separations, exploiting a general numerical approach for computing heat transfer in arbitrary geometries and materials based on the finite-difference time-domain method. Our simulations reveal a tradeoff between selectivity and near-field enhancement as the slab--slab separation decreases, with the patterned heat transfer eventually reducing to the unpatterned result multiplied by a fill factor (described by a standard proximity approximation). We also find that heat transfer can be further enhanced at selective frequencies when the slabs are brought into a glide-symmetric configuration, a consequence of the degeneracies associated with the non-symmorphic symmetry group.

We predict that the effective nonlinear optical susceptibility can be tailored using the Purcell effect. While this is a general physical principle that applies to a wide variety of nonlinearities, we specifically investigate the Kerr nonlinearity. We show theoretically that using the Purcell effect for frequencies close to an atomic resonance can substantially influence the resultant Kerr nonlinearity for light of all (even highly detuned) frequencies. For example, in realistic physical systems, enhancement of the Kerr coefficient by one to two orders of magnitude could be achieved.

We present a method of using a nuclear magnetic resonance computer to solve the Deutsch-Jozsa problem in which: (1) the number of molecules in the NMR sample is irrelevant to the number of qubits available to an NMR quantum computer, and (2) the initial state is chosen to be the state of thermal equilibrium, thereby avoiding the preparation of pseudopure states and the resulting exponential loss of signal as the number of qubits increases. The algorithm is described along with its experimental implementation using four active qubits. As expected, measured spectra demonstrate a clear distinction between constant and balanced functions., Comment: including 4 figures

We calculate the photonic band structure at normal incidence of highly deformable, self-assembling systems - cholesteric elastomers subjected to external stress. Cholesterics display brilliant reflection and lasing owing to gaps in their photonic band structure. The band structure of cholesteric elastomers varies sensitively with strain, showing new gaps opening up and shifting in frequency. A novel prediction of a total band gap is made, and is expected to occur in the vicinity of the previously observed de Vries bandgap, which is only for one polarisation.

We demonstrate a five-bit nuclear-magnetic-resonance quantum computer that distinguishes among various functions on four bits, making use of quantum parallelism. Its construction draws on the recognition of the sufficiency of linear coupling along a chain of nuclear spins, the synthesis of a suitably coupled molecule, and the use of a multi-channel spectrometer., Comment: 7 pages, 4 figures, 1 table