The interaction of quantum systems with mechanical resonators is of practical interest for applications in quantum information and sensing and also of fundamental interest as hybrid quantum systems. Achieving a large and tunable interaction strength is of great importance in this field as it enables controlled access to the quantum limit of motion and coherent interactions between different quantum systems. This has been challenging with solid state spins, where typically the coupling is weak and cannot be tuned. Here we use pairs of coupled quantum dots embedded within cantilevers to achieve a high coupling strength of the singlet-triplet spin system to mechanical motion through strain. Two methods of achieving strong, tunable coupling are demonstrated. The first is through different strain-induced energy shifts for the two QDs when the cantilever vibrates, resulting in changes to the exchange interaction. The second is through a laser-driven AC Stark shift that is sensitive to strain-induced shifts of the optical transitions. Both of these mechanisms can be tuned to zero with electrical bias or laser power, respectively, and give large spin-mechanical coupling strengths.
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http://dx.doi.org/10.1021/acs.nanolett.9b02207 | DOI Listing |
Acc Chem Res
December 2024
Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas 66045, United States.
ConspectusThe surface of a catalyst is crucial for understanding the mechanisms of catalytic reactions at the molecular level and developing new catalysts with higher activity, selectivity, and durability. Ambient pressure X-ray photoelectron spectroscopy (AP-XPS) is a technique studying the surface of a sample in the gas phase, mainly identifying chemical identity, analyzing oxidation state, and measuring surface composition.In the last decade, numerous photoelectron spectroscopic methods for fundamental studies of key topics in catalysis using AP-XPS have been developed.
View Article and Find Full Text PDFPLoS One
December 2024
Department of Electrical Engineering, Stanford University, Stanford, California, United States of America.
We present a model for the noise and inherent stochasticity of fluorescence signals in both continuous wave (CW) and time-gated (TG) conditions. When the fluorophores are subjected to an arbitrary excitation photon flux, we apply the model and compute the evolution of the probability mass function (pmf) for each quantum state comprising a fluorophore's electronic structure, and hence the dynamics of the resulting emission photon flux. Both the ensemble and stochastic models presented in this work have been verified using Monte Carlo molecular dynamic simulations that utilize the Gillespie algorithm.
View Article and Find Full Text PDFChemphyschem
December 2024
Freie Universität Berlin: Freie Universitat Berlin, Dahlem Center of Complex Quantum Systems and Fachbereich Physik, Arnimallee 14, 14195, Berlin, GERMANY.
Quantum chemical calculations of one-photon absorption, electronic circular dichroism and anisotropy factor spectra for the A-band transition of fenchone, camphor and 3-methylcyclopentanone (3MCP) are reported. While the only weakly allowed nature of the transition leads to comparatively large anisotropies, a proper theoretical description of the absorption for such a transition requires to account for non-Condon effects. We present experimental data for the anisotropy of 3MCP in the liquid phase and show that corresponding Herzberg-Teller corrections are critical to reproduce the main experimental features.
View Article and Find Full Text PDFJ Phys Chem Lett
December 2024
Institute of Optoelectronic Technology, Fuzhou University, Fuzhou 350116, China.
The rise of big data and the internet of things has driven the demand for multimodal sensing and high-efficiency low-latency processing. Inspired by the human sensory system, we present a multifunctional optoelectronic-memristor-based reservoir computing (OM-RC) system by utilizing a CuSCN/PbS quantum dots (QDs) heterojunction. The OM-RC system exhibits volatile and nonlinear responses to electrical signals and wide-spectrum optical stimuli covering ultraviolet, visible, and near-infrared (NIR) regions, enabling multitask processing of dynamic signals.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China.
By braiding non-Abelian anyons it is possible to realize fault-tolerant quantum algorithms through the computation of Jones polynomials. So far, this has been an experimentally formidable task. In this Letter, a photonic quantum system employing two-photon correlations and nondissipative imaginary-time evolution is utilized to simulate two inequivalent braiding operations of Majorana zero modes.
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