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Coherent electron spin states within paramagnetic molecules hold significant potential for microscopic quantum sensing. However, all-optical coherence measurements amenable to high spatial and temporal resolution under ambient conditions remain a significant challenge. Here we conduct room-temperature, picosecond time-resolved Faraday ellipticity/rotation (TRFE/R) measurements of the electron spin decoherence time in [IrBr]. Decoherence is strongly sensitive to solution phase viscosity, pointing to molecular tumbling as an important decoherence mechanism. Accordingly, immobilization of [IrBr] molecules in thin polymer films results in an order-of-magnitude increase in coherence lifetime and significantly greater magnetic field sensitivity. By tuning energies of ligand-to-metal charge transfer (LMCT) states, TRFE/R enables spin initialization and readout in the tissue transparency window, paving the way toward all-optical, ultrafast molecular electron spin coherence imaging in biological systems.
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http://dx.doi.org/10.1021/jacs.5c13180 | DOI Listing |
Phys Rev Lett
August 2025
University of Science and Technology of China, Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics, New Cornerstone Science Laboratory, Hefei, Anhui 230026, China.
The multiplicity of orbitals in quantum systems significantly influences the competition between Kondo screening and local spin magnetization. The identification of orbital-specific processes is essential for advancing spintronic devices, as well as for enhancing the understanding of many-body quantum phenomena, but it remains a great challenge. Here, we use a combination of scanning tunneling microscopy/spectroscopy and electron spin resonance (ESR) spectroscopy to investigate single iron phthalocyanine (FePc) molecules on MgO/Ag(100).
View Article and Find Full Text PDFPhys Rev Lett
August 2025
University of Maryland Baltimore County, Department of Physics, Baltimore, Maryland 21250, USA.
A charge qubit couples to environmental electric field fluctuations through its dipole moment, resulting in fast decoherence. We propose the p-orbital (pO) qubit, formed by the single-electron, p-like valence states of a five-electron Si quantum dot, which couples to charge noise through the quadrupole moment. We demonstrate that the pO qubit offers distinct advantages in quality factor, gate speed, readout, and size.
View Article and Find Full Text PDFPhys Rev Lett
August 2025
University of York, School of Physics, Engineering and Technology, York YO10 5DD, United Kingdom.
We propose a model that is able to reproduce the type-II ultrafast demagnetization dynamics observed in 2D magnets. The spin system is coupled to the electronic thermal bath and is treated with atomistic spin dynamics, while the electron and phonon heat baths are described phenomenologically by coupled equations via the two-temperature model. Our proposed two-temperature model takes into account the effect of the heated substrate, which for 2D systems results in a slow demagnetization regime.
View Article and Find Full Text PDFPhys Rev Lett
August 2025
Duke University, Thomas Lord Department of Mechanical Engineering and Materials Science, Durham, North Carolina 27708, USA.
Chiral phonons, which are characterized by rotational atomic motion, offer a unique mechanism for transferring angular momentum from phonons to electron spins and other angular momentum carriers. In this Letter, we present a theoretical investigation into the emergence of chiral phonons in a chiral hybrid organic-inorganic perovskite (HOIP) and their critical roles in rigid-body rotation, magnetic moment generation, and spin transport under nonthermal equilibrium conditions. We demonstrate that phonon angular momentum can modify the spin chemical potential via a proposed microscopic Barnett effect, leading to a spatially varying spin chemical potential at the metal/HOIP interface, which subsequently induces spin currents in an adjacent Cu layer, with a magnitude consistent with experimental observations.
View Article and Find Full Text PDFJ Am Chem Soc
September 2025
Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States.
Coherent electron spin states within paramagnetic molecules hold significant potential for microscopic quantum sensing. However, all-optical coherence measurements amenable to high spatial and temporal resolution under ambient conditions remain a significant challenge. Here we conduct room-temperature, picosecond time-resolved Faraday ellipticity/rotation (TRFE/R) measurements of the electron spin decoherence time in [IrBr].
View Article and Find Full Text PDF