Controlling Emission Wavelength and Chirality of Quantum Emitters in 2D Heterostructures

Han Htoon
Center for Integrated Nanotechnologies, Materials Physics and Applications Division,  Los Alamos National Laboratory, Los Alamos, NM
Wednesday, April 20, 2022
11:00 am
Zoom Seminar
In this talk I will provide a brief overview of two recent accomplishments in my group toward achieving quantum emitters capable of operating in telecommunication wavelength and generating circularly polarized single photons without the need of external magnetic field and spin polarized injection of carriers/excitons.  
First, we demonstrate site-controlled creation of quantum emitters in mono- and few-layer molybdenum ditelluride (MoTe2) using nano-pillar strain engineering technique [1]. The emission wavelength ranges from 1080 nm to 1550 nm, covering all the telecom bands. Photon correlation measurements unambiguously prove the single-photon nature of the emitters. Polarization-resolved magneto-optical spectroscopies reveal the presence of a fine-structure and a large zero-field energy splitting (> 1 meV). The polarization pattern of the quantum emitters are modulated by an external magnetic field, demonstrating the successful incorporation of valley pseudospin into the flying qubits. Our results extend the quantum optics research of 2D TMDCs into the NIR regime for the first time, and establish layered MoTe2 as a new platform for telecom quantum light emission. 

Second, we demonstrate free space chiral quantum light generation independent of laser excitation polarization and at zero magnetic field by strain-engineering a van der Waals heterostructures comprising NiPS3 and single monolayers of WSe2­ [2].  We utilized atomic force microscope tip to creates nanoscale indentations in WSe2/NiPS3 heterostructure placed on top of a polymer layer.  Strain of a nano-indentation creates a ferromagnetic domain in NiPS3 and a quantum emitter (QE) in WSe2 at the same location. The QE emits chiral single photon due to proximity to the ferromagnetic domain. Polarization resolved PL spectra show QE emitting strongly circularly polarized (chiral) light independent of excitation at zero magnetic field and Hanbury Brown and Twiss experiment yield single photon emission with >85% purity. This work represents a significant advance, in that we exploit magnetic proximity interactions for the first time to realize free-space, zero-field generation of chiral quantum light.  Because NiPS3 can support magnons, this work also open new path to realize magnon based quantum transduction platforms.



[1] Zhao, H.;  Pettes, M. T.;  Zheng, Y.; Htoon, H., Site-controlled telecom-wavelength single-photon emitters in atomically-thin MoTe2. Nature communications 2021, 12, DOI : 10.1038/s41467-021-27033-w
[2]  Li, X.; Jones, A. C.; Choi, J.; Zhao, H.; Chandrasekaran, V.;  Pettes, M. T.; Piryatinski, A.; Sinitsyn, N.; Crooker, S. A.; Htoon, H. Proximity Induced Chiral Quantum Light Generation in Strain-Engineered WSe2/NiPS3 Heterostructures.
Luis A. Jauregui