A5001920716- 2D Materials and Applications
- Perovskite Materials and Applications
- Graphene research and applications
- Mechanical and Optical Resonators
- Molecular Junctions and Nanostructures
- Quantum and electron transport phenomena
- Plasmonic and Surface Plasmon Research
- Diamond and Carbon-based Materials Research
- Electronic and Structural Properties of Oxides
- Semiconductor Quantum Structures and Devices
- Quantum Dots Synthesis And Properties
- Nanowire Synthesis and Applications
- Chalcogenide Semiconductor Thin Films
- Strong Light-Matter Interactions
- Photonic and Optical Devices
- Metamaterials and Metasurfaces Applications
- Neural Networks and Reservoir Computing
- MXene and MAX Phase Materials
- Advanced Fiber Laser Technologies
- Topological Materials and Phenomena
- Organic and Molecular Conductors Research
- Force Microscopy Techniques and Applications
- Atomic and Subatomic Physics Research
- Quantum optics and atomic interactions
- Quantum, superfluid, helium dynamics
Stanford University
2023-2025
Harvard University Press
2025
Harvard University
2017-2024
University of Geneva
2020
Columbia University
2017
We demonstrate that a single layer of MoSe_{2} encapsulated by hexagonal boron nitride can act as an electrically switchable mirror at cryogenic temperatures, reflecting up to 85% incident light the excitonic resonance. This high reflectance is direct consequence excellent coherence properties excitons in this atomically thin semiconductor. show monolayer exhibits power-and wavelength-dependent nonlinearities stem from exciton-based lattice heating case continuous-wave excitation and...
Excitons in semiconductors, bound pairs of excited electrons and holes, can form the basis for new classes quantum optoelectronic devices. A van der Waals heterostructure built from atomically thin semiconducting transition metal dichalcogenides (TMDs) enables formation excitons holes distinct layers, producing interlayer with large binding energy a long lifetime. Employing heterostructures monolayer TMDs, we realize optical electrical generation long-lived neutral charged excitons. We...
The twist degree of freedom provides a powerful new tool for engineering the electrical and optical properties van der Waals heterostructures. Here, we show that angle can be used to control spin-valley transition metal dichalcogenide bilayers by changing momentum alignment valleys in two layers. Specifically, observe interlayer excitons twisted WSe$_2$/WSe$_2$ exhibit high (>60%) circular polarization (DOCP) long valley lifetimes (>40 ns) at zero electric magnetic fields. lifetime tuned...
We demonstrate a new approach for dynamically manipulating the optical response of an atomically thin semiconductor, monolayer MoSe2, by suspending it over metallic mirror. First, we show that suspended van der Waals heterostructures incorporating MoSe2 host spatially homogeneous, lifetime-broadened excitons. Then, interface this nearly ideal excitonic system with mirror and control exciton-photon coupling. Specifically, electromechanically changing distance between heterostructure mirror,...
In WSe2 monolayers, strain has been used to control the energy of excitons, induce funneling, and realize single-photon sources. Here, we developed a technique for probing dynamics free excitons in nanoscale landscapes such monolayers. A nanosculpted tapered optical fiber is simultaneously generate probe near-field response monolayers at 5 K. When monolayer pushed by fiber, its lowest states shift as much 390 meV (>20% bandgap monolayer). Polarization lifetime measurements these red-shifting...
The negatively charged tin-vacancy (SnV-) center in diamond is a promising solid-state qubit for applications quantum networking due to its high efficiency, strong zero phonon emission, and reduced sensitivity electrical noise. SnV- has large spin-orbit coupling, which allows long spin lifetimes at elevated temperatures, but unfortunately suppresses the magnetic dipole transitions desired control. Here, by use of naturally strained center, we overcome this limitation achieve high-fidelity...
We report a robust approach to fabricate single-molecule transistors with covalent electrode–molecule–electrode chemical bonds, ultrashort (∼1 nm) molecular channels, and high coupling yield. obtain nanometer-scale gaps from feedback-controlled electroburning of graphene constrictions bridge these molecules using reaction chemistry on the oxidized edges. Using nanogaps, we are able optimize achieve reconnection yield bridges. The length molecule is found influence fraction covalently...
We realize a new electroplasmonic switch based upon electrically tunable exciton–plasmon interactions. The device consists of hexagonal boron nitride (hBN)-encapsulated tungsten diselenide (WSe2) monolayer on top single-crystalline silver substrate. ultrasmooth substrate serves dual role as the medium to support surface plasmon polaritons (SPPs) and bottom gate electrode tune WSe2 exciton energy brightness through electrostatic doping. To enhance coupling, we implement plasmonic crystal...
Excitons are composite bosons that can feature spin singlet and triplet states. In usual semiconductors, without an additional spin-flip mechanism, excitons extremely inefficient optical emitters. Transition metal dichalcogenides (TMDs), with their large spin-orbit coupling, have been of special interest for valleytronic applications coupling circularly polarized light to selective valley spin$^{1-4}$. atomically thin MoSe$_2$/WSe$_2$ TMD van der Waals (vdW) heterostructures, the unique...
A mirror twin boundary (MTB) in a transition metal dichalcogenide monolayer can host one-dimensional electron liquid of topological nature with tunable interactions. Unfortunately, electrical characterization such boundaries has been challenging due to the paucity samples large enough size and high quality. Here, we report conductance measurements individual MTBs epitaxially grown molybdenum disulfide bicrystals that are tens micrometers long. These exhibit power-law behaviors as function...
Atomically thin semiconductor heterostructures provide a two-dimensional (2D) device platform for creating high densities of cold, controllable excitons. Interlayer excitons (IEs), bound electrons and holes localized to separate 2D quantum well layers, have permanent out-of-plane dipole moments long lifetimes, allowing their spatial distribution be tuned on demand. Here, we employ electrostatic gates trap IEs control density. By electrically modulating the IE Stark shift, electron-hole pair...
The negatively charged tin-vacancy center in diamond (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msup><a:mrow><a:mi>SnV</a:mi></a:mrow><a:mrow><a:mo>−</a:mo></a:mrow></a:msup></a:mrow></a:math>) is an emerging platform for building the next generation of long-distance quantum networks. This due to <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"...
Efficient nanophotonic devices are essential for applications in quantum networking, optical information processing, sensing, and nonlinear optics. Extensive research efforts have focused on integrating two-dimensional (2D) materials into photonic structures, but this integration is often limited by size material quality. Here, we use hexagonal boron nitride (hBN), a benchmark choice encapsulating atomically thin materials, as waveguiding layer while simultaneously improving the quality of...
Techniques to mold the flow of light on subwavelength scales enable fundamentally new optical systems and device applications. The realization programmable, active with fast, tunable components is among outstanding challenges in field. Here, we experimentally demonstrate a few-pixel beam steering based electrostatic gate control excitons an atomically thin semiconductor strong light-matter interactions. By combining high reflectivity MoSe2 monolayer graphene split-gate geometry, shape...
The growth of single crystals MoS2 and WS2 by materials transport through a liquid salt flux made from low-melting mixture NaCl CsCl is presented. are structurally characterized single-crystal X-ray diffraction, which reveals that the 2H-MoS2 contain very small percentage (about 3%) 3R intergrowths 2H-WS2 display less than 1% intergrowths. Characterization scanning electron microscopy presented as photoluminescence spectra exfoliated monolayers show grown this method superior in quality to...