We report on microwave-driven coherent electron transfer between two coupled donors embedded in a silicon nanowire. By increasing the microwave frequency we observe a transition from incoherent to coherent driving revealed by the emergence of a Landau-Zener-Stückelberg quantum interference pattern of the measured current through the donors. This interference pattern is fitted to extract characteristic parameters of the double-donor system. In particular we estimate a charge dephasing time of 0.3±0.1 ns, comparable to other types of charge-based two-level systems. The demonstrated coherent coupling between two dopants is an important step towards donor-based quantum computing devices in silicon.
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http://dx.doi.org/10.1103/PhysRevLett.110.136802 | DOI Listing |
Struct Dyn
January 2025
Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany.
Sub-ångström spatial resolution of electron density coupled with sub-femtosecond to few-femtosecond temporal resolution is required to directly observe the dynamics of the electronic structure of a molecule after photoinitiation or some other ultrafast perturbation, such as by soft X-rays. Meeting this challenge, pushing the field of quantum crystallography to attosecond timescales, would bring insights into how the electronic and nuclear degrees of freedom couple, enable the study of quantum coherences involved in molecular dynamics, and ultimately enable these dynamics to be controlled. Here, we propose to reach this realm by employing convergent-beam x-ray crystallography with high-power attosecond pulses from a hard-x-ray free-electron laser.
View Article and Find Full Text PDFRandom lasers (RLs) with a simple structure and low-cost properties have been recognized as an ideal analytical platform and are still challenging for liquid detecting, remaining beset for low sensitivity, complicated operation, and large analyte consumption. Here, inspired by a microfluidic sensor, a microtubule structured random laser for multifunctional sensing is demonstrated. The random laser is achieved resorting to a curly PMMA film with gain and scatterers embedded in it.
View Article and Find Full Text PDFNature
January 2025
Department of Physics, Durham University, Durham, United Kingdom.
Realizing quantum control and entanglement of particles is crucial for advancing both quantum technologies and fundamental science. Substantial developments in this domain have been achieved in a variety of systems. In this context, ultracold polar molecules offer new and unique opportunities because of their more complex internal structure associated with vibration and rotation, coupled with the existence of long-range interactions.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
The unique reactivity of molecules under force commands an understanding of structure-mechanochemical activity relationships. While conceptual frameworks for understanding force transduction in many systems are established, systematic investigations into force-coupled molecular torsions are limited. Here, we describe a novel fluorenyl naphthopyran mechanophore for which mechanical force is uniquely coupled to the torsional motions associated with the overall chemical transformation as a result of the conformational rigidity imposed by the fluorene group.
View Article and Find Full Text PDFChaos
January 2025
Complex Systems Group, Department of Mathematics and Statistics, The University of Western Australia, Crawley, Western Australia 6009, Australia.
We propose a universal method based on deep reinforcement learning (specifically, soft actor-critic) to control the chimera state in the coupled oscillators. The policy for control is learned by maximizing the expectation of the cumulative reward in the reinforcement learning framework. With the aid of the local order parameter, we design a class of reward functions for controlling the chimera state, specifically confining the spatial position of coherent and incoherent domains to any desired lateral position of oscillators.
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