We investigate the emergence and topological nature of interface states (IFs) in N-AGNR/(N − 2)-AGNR/N-AGNR heterostructure (AGNRH) segments lacking translational symmetry, focusing on their relation to the end states (ESs) of the constituent armchair graphene nanoribbon (AGNR) segments. For AGNRs with R1-type unit cells, the ES numbers under a longitudinal electric field follow the relations N = NA(B) × 6 + 1 and N = NA(B) × 6 + 3, whereas R2-type unit cells exhibit (NA(B) + 1) ESs. The subscripts A and B denote the chirality types of the ESs. The Stark effect lifts ES degeneracy and enables clear spectral separation between ESs and IFs. Using a real-space bulk boundary perturbation approach, we show that opposite-chirality states hybridize through junction-site perturbations and may shift out of the bulk gap. The number and chirality of IFs in symmetric AGNRHs are determined by the difference between the ESs of the outer and central segments, NO and NC, according to NIF,β = |NO,B(A) − NC,A(B)|, where β labels the chirality. Depending on whether NO > NC or NC > NO, the resulting IFs acquire B- or A-chirality, respectively. Calculated transmission spectra reveal that AGNRHs host a topological double quantum dot (TDQD) when IFs originate from the ESs of the central AGNR segment. Using an Anderson model with effective intra-dot and inter-dot Coulomb interactions, we derive an analytical expression for the tunneling current through the TDQD via a closed-form transmission coefficient. Thermoelectric analysis shows that TDQDs yield enhanced nonlinear power output in the electron-dilute and hole-dilute charge states, with Coulomb blockade suppressing thermal current but not thermal voltage. The thermal power output of the TDQD is significantly enhanced by nonlinear effects, even under strong electron Coulomb interactions.

This work presents a Rydberg-atom-based Loran-C receiver designed to overcome long-standing limitations of conventional systems, including low sensitivity and bulky form factors. In the proposed design, a reference electrode couples the low-frequency Loran-C signal into an atomic vapor cell equipped with integrated parallel plates; an auxiliary DC bias field is applied to optimize this coupling. By leveraging electromagnetically induced transparency (EIT) in conjunction with the Stark effect, the receiver enables direct, high-sensitivity measurement of the electric field's amplitude and phase. An FPGA-based acquisition stage and a MATLAB signal-processing pipeline were implemented to perform ground-wave/sky-wave discrimination, time-difference-of-arrival (TDOA) estimation, position fixing, and timing recovery. Experimental results confirm that the Rydberg-atom-based receiver successfully provides both positioning and timing capabilities. These findings demonstrate that Rydberg-atom sensors can significantly enhance the sensitivity and dynamic range of Loran-C systems at low frequencies, thereby establishing a quantum-sensing pathway toward next-generation, high-reliability navigation and timing architectures.

Abstract Light‐matter strong coupling generates polariton states, which not only are the subject of fundamental physics studies but may also enable transformative technologies in lasing, optical switching, and chemistry. The exciton polaritons of semiconductors and molecules have been extensively studied. Here, we study the strong light‐matter interaction of magic‐size nanoclusters (MSCs), which can be considered as extremely confined nanocrystals that bridge the gap between semiconductors and small molecules. It is found that Cd 3 P 2 MSCs, with superior size monodispersity and large oscillator strength, enable room‐temperature strong coupling in a tunable Fabry–Pérot microcavity, with the Rabi splitting reaching 160 meV. Importantly, the derived transition dipole moment of Cd 3 P 2 MSCs is consistent with that obtained from optical Stark effect measurements. The four orders‐of‐magnitude difference in electric field strength, however, highlights the essence of collective strong coupling in a microcavity in comparison to coupling with the light field in laser pulses.

Abstract We report the fabrication of red-emitting micro-light-emitting diodes (μLEDs) based on InGaN nanoplatelets graded indium composition p-InGaN layers. The Mg concentration in the nanoplatelet-based p-InGaN was found to be highly sensitive to precursor flux, exhibiting self-compensation effects at high doping levels. 10 × 10 μm² μLEDs, consisting of about 400 nanoplatelets, exhibit electroluminescence (EL) at 665 nm with a full width at half maximum (FWHM) of 90 nm. Furthermore, compared with the photoluminescence (PL) peak at 618 nm, the EL redshift attributed to the quantum-confined Stark effect (QCSE) at low injection levels is discussed.

Here, a technique for implementing an all-optical wavelength converter based on the quantum-confined Stark effect (QCSE) influenced by piezoelectric fields in a semiconductor optical amplifier with compressively strained zinc-blende multi-quantum well grown along the [111]A direction and embedded in the intrinsic layer of a p-i-n diode is presented. The originality and crucial aspect of the technique used is that the piezoelectric fields, induced by the compressive strain within the quantum wells (QWs) of the amplifier with an orientation parallel to that of the built-in field of the structure, make it possible to accelerate the absorption recovery and to perform a fast wavelength conversion over a wide range of the continuum. Specifically, the built-in p-i-n electric field and the piezoelectric fields induce a QCSE and unevenly tilt the potential energy profile of the QWs. This dramatically reduces the energy between the effective height of barriers and the quantized energy of carriers, remarkably due to the piezoelectric fields, thereby decreasing the escape time of carriers from wells and accelerating absorption recovery. Consequently, a strong negative chirp is induced into the converted signal pulses, allowing their compression after passing through a blue-shifted optical filter. Up- and down-conversions at 150 and 1300 Gb/s, respectively, were theoretically predicted in an ideal case, and experimentally, both were error-free demonstrated at 40 Gb/s in a total range of 29 nm, employing a straightforward scheme, with the possibility of operating at 100 Gb/s.

Theory of vibrational Stark effect for adsorbates and diatomic molecules

Tunable binding energy, stark shift and photoionization cross-section of 2D-hemicylindrical nanostructure under non-resonant laser and electric fields

Abstract Stimulated Raman scattering (SRS) is highly relevant to quantum memories
involving Raman system. Using quantum Langevin equations with complete noise
operators couples to the quantum field propagation equation we present a
general theory of SRS for moving quantum particles where quantum Stokes
pulse couples to both transitions (m1 and m3) while an arbitrary laser pulses
couple to only one (m1) transition. Our coupled equations contain dynamical
ac Stark shift due to laser pulses, complete quantum noise operators and atomic coherences corresponding to all possible three transitions (not only the ground state coherence), quantum mechanical microscopic expressions for linear and nonlinear
interactions with nonlocal (memory) or temporal dispersion effects. We
obtain analytical solution of the quantum Stokes field in laboratory
spacetime with generalized quantum noise operators that include all initial atomic coherences and arbitrary initial
and boundary quantum fields, valid for arbitrary laser pulses. The general
solution provides a complete physical picture, composed of basically two
parts: above and below the light line, t=z/c. This robust framework offers a
powerful tool for optimizing Raman-based quantum information processes,
particularly for modeling the spatial-temporal dynamics of quantum Stokes
pulses in storage and retrieval stages of quantum memory.

In this work, we stabilize a 1556.2nm fiber laser to the 5S1/2 → 5D5/2 two-photon transition in 87Rb in a carefully designed compact physics package. A commercial fiber frequency comb divides the optical frequency into 200MHz microwave output, which demonstrates a fractional frequency stability of 2.2 × 10-13 at τ = 1 s and 8.1 × 10-15 at τ = 4000 s, without linear drift removal. We analyze the systematic effect on the short-term and long-term stabilities in detail. The short-term and long-term stabilities are limited by shot noise and ac Stark shift, respectively. The rubidium two-photon optical clock is a promising candidate for the next-generation space-borne atomic clock.

Most light-emitting devices based on quantum-confined structures are commonly utilized as electrically injected devices. However, the electric-field-dependent energy band gap induced by the quantum confinement Stark effect (QCSE) usually hinders the realization of frequency-stable laser devices. This is because the change in the energy band gap, which also means the corresponding change in the photon energy, will result in an electric-field-dependent frequency. Here, we propose a novel approach to mitigate this electric-field-dependent variation in the energy band gap by employing a gradient quantum system. In this system, the energy band edges are inclined due to the action of the indium (In)-segregation effect. This special design can effectively weaken the changes in the band profile associated with the electric field effect and counteract the electric-field-dependent band gap variations within the active region to a certain extent. Experimental studies indicate that the energy band gap of this gradient quantum system remains almost unchanged (<18.9 μeV cm2/A) even under a relatively strong applied electric field. Meanwhile, compared with the traditional GaAs quantum well, the efficiency improvement in the band gap stability of our nanowire–well gradient system is 64.1 % and 70.6 % for the TE and TM polarization modes, respectively, which suggests that our proposed gradient quantum structure can significantly mitigate the electric-field-induced change in the energy band gap. This achievement is of great significance for advancing the development of high-performance frequency-stable laser devices in some advanced fields, such as quantum sensing systems and optical communications.

Interlayer excitons in van der Waals (vdW) heterostructures (HSs) have garnered significant attention due to their unique properties, including prolonged lifetimes and long-range transport. While extensive studies have been conducted on interlayer excitons in HSs composed of different monolayers, research on HSs formed by multilayer constituents remains limited, particularly regarding dipole moments, which play a crucial role in light-matter interactions. In this study, we investigate the dipole moments of interlayer excitons in multilayer WS₂ and InSe HSs using the quantum-confined Stark effect. Our findings reveal that the dipole moment increases monotonically with the number of layers in InSe or WS₂, reaching a maximum of 3.18 e nm, which is the largest value reported to date. Consequently, the dipole-dipole interaction is enhanced with the increasing layer number, as demonstrated by excitation power-dependent measurements. Ab initio calculations further support our experimental results, indicating the delocalization of the excitonic wave function with increasing layer thickness. Our findings introduce a novel layer-engineered mechanism for tuning the dipole moments of interlayer excitons in vdW heterostructures, paving the way for manipulating many-body interactions in low-dimensional quantum systems.

Intrinsic, oriented electric fields inside protein active sites, quantified by vibrational Stark effect (VSE) measurements and electrostatic calculations have been implicated in catalytic preorganization, yet their systematic use to program drug-target lifetimes has remained underexplored. We advance a field-first paradigm in which the component of the protein field projected along a dominant reaction coordinate, denoted as (the component of the protein's electric field along the reaction coordinate), serves as a tunable design variable for off-rate and residence time (τ). Focusing on two mechanistic archetypes proton sharing (Ketosteroid Isomerase, KSI-like) and bond polarization/dissociation (human aldose reductase, hALR2-like) we show that realistic changes in can tilt barriers, alter curvatures, and modulate tunneling, yielding exponential leverage on kinetics. This reframes pharmacodynamic lifetime as an electrostatic, geometry-addressable property, complementary to affinity optimization and accessible through protein mutations or ligand substituents that re-orient local dipoles. We developed a predictive, quantum-mechanical framework grounded in analytical solutions to the one-dimensional time-independent Schrödinger equation. Two experimentally validated systems were modeled viz the proton-transfer dynamics in ketosteroid isomerase (KSI) using an asymmetric double-well potential, and carbonyl polarization/dissociation in human aldose reductase (hALR2) using a modified Morse potential. The intrinsic Stark field was incorporated via its projection onto the reaction coordinate ( ), coupling through molecular dipole and polarizability terms to tilt and reshape the potential energy landscape. The resulting eigenvalues and wavefunctions provided the parameters for a Grote-Hynes-corrected transition-state theory model with explicit quantum tunneling corrections. This approach quantitatively connects field strength to activation barriers, vibrational frequencies, and ultimately the off-rate ( ), enabling the prediction of how perturbations via mutagenesis or ligand design alter residence time.

Upon excitation by a strong coherent light field, photon-dressed states form and hybridize with equilibrium states, leading to transient band renormalization, a phenomenon known as the optical Stark effect (OSE). Extensive research has been conducted on the optical control of the OSE by modulating the optical pump fluence, detuning energy, and polarization. Herein, we present the electrical tuning of valley-selective OSE in a back-gated monolayer WS2 device using helicity-resolved transient absorption spectroscopy (TAS). The mechanism involves an enhanced transition dipole moment and exciton oscillator strength under electrical control. The OSE blue shift deviates from the exciton intensity trend at high negative voltages, arguing against a simple interpretation from the steady-state exciton density of states and suggesting a more complex underlying origin. Our study demonstrates electrical tuning as an additional degree of freedom for Floquet engineering, offering profound insights into coherent light-matter interaction in 2D materials.

Gallium nitride (GaN) offers significant advantages in power electronics due to its high electron mobility, high saturation drift velocity, and low relative permittivity, which enable faster switching speeds and lower conduction losses compared to silicon (Si). These properties position GaN as a strong contender against the traditional dominance of Si in the power electronics market, leading to the potential for smaller, lighter, and more efficient power systems. Currently, GaN is predominantly utilized in lateral, unipolar switching applications, particularly in high-electron mobility transistors (HEMTs). However, its implementation in vertical, bipolar switching devices has been limited due to two main challenges: the short minority carrier lifetime, typically around 1 ns, and the difficulty in achieving large-area devices with buried p-type material. Recent advances, such as minority carrier recombination lifetime control through quantum well-induced charge segregation and improved annealing techniques for buried p-type layers in oxygenated environments, have begun to address these challenges. As a result, the development of vertical GaN devices, including thyristors, insulated-gate bipolar transistors (IGBTs), and current-aperture vertical electron transistors (CAVETs), is becoming more feasible. These innovations could significantly expand the potential of GaN in power electronics to include high power pulsed applications as these challenges are overcome.In this work, we describe our efforts to address the challenges of bipolar device development in a III-nitride system. Specifically, the short minority carrier lifetime is being addressed through the use of the quantum-confined Stark effect (QCSE). We demonstrate the ability to “tune” the minority carrier lifetime based on the materials’ inherent polarization properties. Numerical simulations utilizing a Schrödinger-Poisson solver were conducted to predict carrier lifetimes in GaN quantum wells with varying widths, clad with Al.04Ga.96N barriers. These predict that the radiative lifetime increases up to three orders of magnitude in the GaN layers as a function of well width and the free carrier concentration. The maximum lifetime was found at a well width of approximately 30 nm, and the lifetime gradually approached the bulk lifetime value of 1 ns at larger well widths. To validate the simulation results, time-resolved photoluminescence (TRPL) measurements were performed on samples of varying well widths and excitation power densities. The TRPL experimental values agreed well with the numerical solution. The longest recorded carrier lifetime was approximately 500 ns for a 40 nm well width, demonstrating the significant potential of QCSE to extend carrier lifetimes in GaN.A parallel effort to address the challenge of activating buried p-type material has been underway. Due to H+ binding to the accepter dopant Mg- during metalorganic chemical vapor deposition (MOCVD) growth, the acceptor species is passivated and must be activated by diffusing out the H+. This happens due to three processes: dissociation, diffusion, and desorption. We report on recent advancements annealing in reactive ambients to achieve a higher rate of activation through desorption and thus more uniform and conductive buried p-GaN. This is demonstrated using an oxygen-rich diffusion tube containing N2:O2=4:1 at 800 °C for 30 minutes, resulting in a fully activated 100 µm-diameter buried pn junction. Additionally, fluorinated annealing ambients are being investigated. We have fabricated full thyristor structures with both p- and n-type drift regions. We will discuss the electrical characterization and a mixed-mode TCAD model that has been developed to inform the gate drive characteristics in the context of predicting performance. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy of the United States Government.

Photoelectrochemistry is a promising approach for converting solar energy to storable chemical energy in chemical fuels. The overall photon-to-fuel conversion process consists of multiple elementary steps, including charge separation, recombination, catalytic reactions. While the overall incident light-to-current conversion efficiency (IPCE) can be readily measured, identifying the microscopic efficiency loss processes remains difficult. Although transient absorption spectroscopy is a powerful tool for probing interfacial dynamics in high surface area materials, it is often not applicable on planar electrodes because of a lack of sensitivity for interfacial processes. Furthermore, there lack techniques for directly probing quasi-fermi level shift, electrostatic potential distribution (such as bend bending) and interfacial field that governs the charge carrier separation and recombination and chemical reaction. In this talk, we discuss our recent effort in developing in situ time-resolved linear and nonlinear spectroscopic tools for probing interfacial charge transfer and chemical reactions at planar (photo-) electrode/electrolyte interfaces. Depending on the time availability, the talk may cover some the following four topics. In the first topic, we discuss simultaneous in-situ transient photocurrent and transient reflectance spectroscopy (TRS) measurements of photocathodes for water reduction in photoelectrochemical cells. The kinetics of interfacial charge separation is probed through the built-in electric field change through the Franz-Keldysh effect. This study provides a time-resolved view of microscopic steps involved in the overall light to current conversion process and provides detailed insight on the main loss pathways of the photoelectrochemical system. In the second topic, we discuss a novel method of measuring quasi-Fermi level of catalysts on semiconductor electrodes by Raman spectroscopy. For metal nanoparticle catalysts, the quasi-Fermi level is measured by vibrational stark effect spectroscopy while for molecular catalysts the oxidation states of catalysts are monitored. In the third topic, we discuss the in situ direct probe of the spatially varying electrostatic potential in the semiconductor space charge layer (i.e. the built-in potential) and the electric double layer at the electrode/electrolyte interface by electric field induced second harmonic generation (EFISH). We will discuss how this method is used to probe the change of built-in potential as a function of pH and light illumination, providing insight into rate limiting steps in the overall solar-to-fuel conversion.

Plasma-Induced Excitation and Electron Density Characterization in Atmospheric Cyclonic Discharges via Stark Broadening Spectroscopy

Telecom wavelength quantum dots (QDs) are emerging as a promising solution for generating deterministic single-photons compatible with existing fiber-optic infrastructure. Emission in the low-loss C-band minimizes transmission losses, making them ideal for long-distance quantum communication. In this work, we present a demonstration of both Stark tuning and charge state control of individual InAs/InP QDs operating within the telecom C-band. These QDs are grown by droplet epitaxy and embedded in an InP-based n++-i-n+ heterostructure, fabricated using MOVPE. The gated architecture enables the tuning of emission energy via the quantum-confined Stark effect, with a tuning range exceeding 2.4 nm. It also allows for control over the QD charge occupancy, enabling access to multiple discrete excitonic states. Electrical tuning of the fine-structure splitting is further demonstrated, opening a route to entangled-photon-pair generation at telecom wavelengths. The single-photon character is confirmed via second-order correlation measurements. These advances enable QDs to be tuned into resonance with other systems, such as cavity modes and emitters, marking a critical step toward scalable, fiber-compatible quantum photonic devices.

This study investigates an AlON buffer layer approach to enhance the optoelectronic performance and modulation bandwidth of green µ-LEDs. Compared to traditional AlN buffer layers, the AlON buffer layer improves GaN crystal quality, reduces internal stress, and suppresses the quantum-confined Stark effect. The modulation bandwidth shows a 21.75% enhancement over devices with AlN buffer layers. The peak external quantum efficiency is also improved by 9.86% compared to traditional structures. These results highlight the potential of AlON buffer layers for high-performance green µ-LEDs in both display and visible light communication applications.

Stark effect in the $$SU(2)$$ Yang–Coulomb problem

The Stark effect at high electric fields in the near-infrared spectrum of atomic carbon