Search query:  coupled photon emission from hexagonal boron

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abstract: The ultrafast conversion of electrical signals to optical signals at the nanoscale is of fundamental interest for data processing, telecommunication and optical interconnects. However, the modulation bandwidths of semiconductor light emitting diodes are limited by the spontaneous recombination rate of electron hole pairs, and the footprint of electrically driven ultrafast lasers is too large for practical on chip integration. A metal insulator metal tunnel junction approaches the ultimate size limit of electronic devices and its operating speed is fundamentally limited only by the tunnelling time. Here, we study the conversion of electrons (localized in vertical gold hexagonal boron nitride gold tunnel junctions) to free space photons, mediated by resonant slot antennas. Optical antennas efficiently bridge the size mismatch between nanoscale volumes and far field radiation and strongly enhance the electron photon conversion efficiency. We achieve polarized, directional and resonantly enhanced light emission from inelastic electron tunnelling and establish a novel platform for studying the interaction of electrons with strongly localized electromagnetic fields.
author_names: Markus Parzefall

Palash Bharadwaj

A Jain

Takashi Taniguchi

K Watanabe

Lukas Novotny
title: Antenna coupled photon emission from hexagonal boron nitride tunnel junctions.
venue: Nature nanotechnology
year: 2015

abstract: Single atomic defects in hexagonal boron nitride (hBN) are particularly interesting due to their stability of emission and absence of blinking and bleaching, at ambient conditions [1] Furthermore, they show exceptional robustness of emission, even at high temperatures of operation [2] Therefore, hBN defects have emerged as promising candidates for novel robust single photon sources [1] Several attempts have been done to induce hBN defects in a controlled manner [3,4] Because of their ease of accessibility and, due to the nanometer scale thickness of the hBN flakes, these defects are attractive to couple to plasmonic structures in order to increase their photon emission [5,6] However efficient coupling requires a high precision of positioning <20 nm) and so far the methods adopted lack this level of control, both in assembling and imaging. Also, they present static configurations of coupled emitter particles and no strategy is adopted in order to discern between the photons emitted by the hBN defects and the luminescence of the metallic particles. Here we present first systematic and simultaneous coupling and imaging of hBN emission centers with resonant optical antennas, with nanometer control and optical resolution of 45 nm (fig. a) We show the capability of nano antennas to manipulate hBN defects by depleting their emission 30 70% (fig. a, b) Our setup is a near field microscope working in scattering configuration, where we fabricate a single dipolar nano antenna as a near field probe that we can independently scan over hBN defects controlling the coupling and the fluorescence emission with nanometer resolution [7] We employ a photon time gating technique in order to discriminate the light emitted by the metallic antenna by the one radiated by the hBN emitters (fig. b) Finally, we report on a lifetime shortening of 2x, due to coupling emitter antenna (fig. c, d)
author_names: Nicola Palombo Blascetta

Dmitri K Efetov

Takashi Taniguchi

K Watanabe

Niek F van Hulst
title: Scanning Resonant Nano Antenna High Resolution Imaging and Emission Control of hBN Defect Photon Emission
venue: 2019 Conference on Lasers and Electro Optics Europe European Quantum Electronics Conference (CLEO/Europe EQEC)
year: 2019

abstract: Single photon emitters (SPEs) in hexagonal boron nitride (hBN) have garnered increasing attention over the last few years due to their superior optical properties. However, despite the vast range of experimental results and theoretical calculations, the defect structure responsible for the observed emission has remained elusive. Here, by controlling the incorporation of impurities into hBN via various bottom up synthesis methods and directly through ion implantation, we provide direct evidence that the visible SPEs are carbon related. Room temperature optically detected magnetic resonance is demonstrated on ensembles of these defects. We perform ion implantation experiments and confirm that only carbon implantation creates SPEs in the visible spectral range. Computational analysis of the simplest 12 carbon containing defect species suggest the negatively charged VBCN \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin} 69pt} \begin{document}\rm{V}}_{\rm{B}\rm{C}}_{\rm{N} \end{document} defect as a viable candidate and predict that out of plane deformations make the defect environmentally sensitive. Our results resolve a long standing debate about the origin of single emitters at the visible range in hBN and will be key to the deterministic engineering of these defects for quantum photonic devices. Comparison of hexagonal boron nitride samples grown with different techniques and with varying carbon doping content provides evidence that the defects emitting single photons in the visible range are carbon related.
author_names: Noah Mendelson

Dipankar Chugh

Jeffrey R Reimers

Tin S Cheng

Andreas Gottscholl

Hu Long

Christopher J Mellor

Alex Zettl

Vladimir Dyakonov

Peter H Beton

Sergei V Novikov

Chennupati Jagadish

Hark Hoe Tan

Michael J Ford

Milos Toth

Carlo Bradac

Igor Aharonovich
title: Identifying carbon as the source of visible single photon emission from hexagonal boron nitride
venue: Nature Materials
year: 2020

abstract: Single photon emitters in 2D hexagonal boron nitride (hBN) have attracted a considerable attention because of their highly intense, stable, and strain tunable emission. However, the precise source of this emission, in particular the detailed atomistic structure of the involved crystal defect, remains unknown. In this work, we present first principles calculations of the vibrationally resolved optical fingerprint of the spin triplet (2)(_^3)B_1 to (1)(_^3)B_1 transition of the VNCB point defect in hBN. Based on the excellent agreement with experiments for key spectroscopic quantities such as the emission frequency and polarization, the photoluminescence (PL) line shape, Huang Rhys factor, Debye Waller factor, and re organization energy, we conclusively assign the observed single photon emission at ~2eV to the VNCB defect. Our work thereby resolves a long standing debate about the exact chemical nature of the source of single photon emission from hBN and establishes the microscopic understanding necessary for controlling and applying such photons for quantum technological applications.
author_names: A Sajid

and Kristian S Thygesen
title: VNCB defect as source of single photon emission from hexagonal boron nitride
year: 2020

abstract: Defect centers in two dimensional hexagonal boron nitride (hBN) are drawing attention as single photon emitters with high photo stability at room temperature. With their ultra high photon stability, hBN single photon emitters are promising for new applications in quantum technologies and for two dimensional material based optoelectronics. Here, we control the emission rate of hBN defects by coupling these to resonant plasmonic nanocavities. By deterministic control of the antenna we acquire high resolution emission maps of the single hBN defects. Using time gating, we can discriminate the hBN defect emission from the antenna luminescence. We observe sharp dips (40 nm FWHM) in emission, together with a reduction with the luminescence lifetime. Comparing with FDTD simulations we conclude that both radiative and non radiative rates are enhanced, which effectively reduce the quantum efficiency. Also, the large refractive index of the hBN largely screens off the local antenna field enhancement. Finally, based on the insight gained, we propose a close contact design for an order of magnitude brighter hBN single photon emission.
author_names: Nicola Palombo Blascetta

Matz Liebel

Xiaobo Lu

Takashi Taniguchi

Kenji Watanabe

Dmitri K Efetov

Niek F van Hulst
title: Nanoscale Imaging and Control of hexagonal Boron Nitride Single Photon Emitters by a Resonant Nano antenna.
venue: Nano letters
year: 2020

abstract: For quantum photonic applications, such as quantum communication, optical quantum information processing, and metrology, solid state sources of single photon emitters are highly needed. Recently, single photon emitters in two dimensional (2D) van der Waals materials have attracted tremendous attention because of their atomic thickness, allowing for high photon extraction efficiency and easy integration into photonic circuits. In particular, a defect hosted by 2D hexagonal boron nitride (hBN) is expected to be a promising candidate for next generation single photon sources due to its chemical and thermal stability and high brightness at room temperature. Here, we report an effective method for generating single photon emission in mechanically exfoliated hBN flakes by annealing in a carbon rich environment. The one step annealing in a mixed atmosphere (Ar:CH4:H2 15:5:1) greatly increases the single photon emitter density in hBN. The resulting single photon emission shows high stability and brightness. Our results provide an effective method for generating room temperature single photon emitters in 2D hBN.
author_names: Chao Lyu

Yaozheng Zhu

Pingfan Gu

Jiandong Qiao

Kenji Watanabe

Takashi Taniguchi

Yu Ye
title: Single photon emission from two dimensional hexagonal boron nitride annealed in a carbon rich environment
year: 2020

abstract: The generation of non classical light states in the near infrared (NIR) is important for a number of photonic quantum technologies. Here, we report the first experimental observation of sub Poissonian NIR (1.24 eV) light emission from defects in a 2D hexagonal boron nitride (hBN) sheet at room temperature. Photoluminescence statistics shows g(2)(0) 0.6, which is a signature of the quantum nature of the emission. Density functional theory calculations, at the level of the generalized gradient approximation, for the negatively charged nitrogen anti site lattice defects are consistent with the observed emission energy. This work demonstrates that the defects in hBN could be a promising platform for single photon generation in the NIR.
author_names: Robin Camphausen

Loris Marini

Sherif Abdulkader Tawfik

Toan Trong Tran

Michael J Ford

Stefano Palomba
title: Observation of near infrared sub Poissonian photon emission in hexagonal boron nitride at room temperature
year: 2020

abstract: Artificial atomic systems in solids are becoming increasingly important building blocks in quantum information processing and scalable quantum nanophotonic networks. Amongst numerous candidates, 2D hexagonal boron nitride has recently emerged as a promising platform hosting single photon emitters. Here, we report a number of robust plasma and thermal annealing methods for fabrication of emitters in tape exfoliated hexagonal boron nitride (hBN) crystals. A two step process comprising Ar plasma etching and subsequent annealing in Ar is highly robust, and yields an eight fold increase in the concentration of emitters in hBN. The initial plasma etching step generates emitters that suffer from blinking and bleaching, whereas the two step process yields emitters that are photostable at room temperature with emission wavelengths greater than ~700 nm. Density functional theory modeling suggests that the emitters might be associated with defect complexes that contain oxygen. This is further confirmed by generating the emitters via annealing hBN in air. Our findings advance the present understanding of the structure of quantum emitters in hBN and enhance the nanofabrication toolkit needed to realize integrated quantum nanophotonic circuits.
author_names: Zai-Quan Xu

Christopher Elbadawi

Toan Trong Tran

Mehran Kianinia

Xiuling Li

Daobin Liu

Timothy B Hoffman

Minh Hieu Nguyen

Sejeong Kim

James H Edgar

Xiaojun Wu

Li Song

Sajid Ali

Michael J Ford

Milos Toth

Igor Aharonovich
title: Single photon emission from plasma treated 2D hexagonal boron nitride.
venue: Nanoscale
year: 2018

abstract: In this Letter, we demonstrate strong light emission from defective hexagonal boron nitride (hBN) defect centers upon their coupling with disorder near touching plasmonic units. Based on numerical simulations and characterization results, the plasmonic design at thin layer thicknesses of 20 nm can provide above 2 orders of magnitude enhancement in photoluminescence (PL) spectra. Moreover, this plasmonic platform shortens the luminescence lifetime of the emitters. The proposed design can be easily extended to other plasmonic emitter combinations where strong light matter interaction can be achieved using large scale compatible routes.
author_names: Zeinab Eftekhari

Amir Ghobadi

Mahmut Can Soydan

Deniz Umut Yildirim

Neval A Cinel

Ekmel Ozbay
title: Strong light emission from a defective hexagonal boron nitride monolayer coupled to near touching random plasmonic nanounits.
venue: Optics letters
year: 2021

abstract: Two dimensional van der Waals materials have emerged as promising platforms for solid state quantum information processing devices with unusual potential for heterogeneous assembly. Recently, bright and photostable single photon emitters were reported from atomic defects in layered hexagonal boron nitride (hBN) but controlling inhomogeneous spectral distribution and reducing multi photon emission presented open challenges. Here, we demonstrate that strain control allows spectral tunability of hBN single photon emitters over 6 meV, and material processing sharply improves the single photon purity. We observe high single photon count rates exceeding 7 x 106 counts per second at saturation, after correcting for uncorrelated photon background. Furthermore, these emitters are stable to material transfer to other substrates. High purity and photostable single photon emission at room temperature, together with spectral tunability and transferability, opens the door to scalable integration of high quality quantum emitters in photonic quantum technologies.Inhomogeneous spectral distribution and multi photon emission are currently hindering the use of defects in layered hBN as reliable single photon emitters. Here, the authors demonstrate strain controlled wavelength tuning and increased single photon purity through suitable material processing.
author_names: Gabriele Grosso

Hyowon Moon

Benjamin Lienhard

Sajid Ali

Dmitri K Efetov

Marco M Furchi

Pablo Jarillo-Herrero

Michael J Ford

Igor Aharonovich

Dirk R Englund
title: Tunable and high purity room temperature single photon emission from atomic defects in hexagonal boron nitride
venue: Nature Communications
year: 2017