2025/04/09 by Jingyan Xu, Raphael Kircher, Xu, Jingyan +7 · 1 voice · 2 citations
Physics and Astronomy · #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Quantum Physics (quant-ph) #physics.chem-ph #quant-ph
paper · pdf · doi:10.48550/arxiv.2504.06498
arxiv published 2025/04/09 · arxiv updated 2025/06/18
We introduce quantum J-oscillators that exploit intrinsic nuclear spin-spin (scalar J) couplings in molecules to produce phase-coherent oscillations. Operated in zero magnetic field and driven by a digital feedback, they operate from sub-hertz to a few tens of hertz frequencies. In a proof-of-principle experiment on [15N]-acetonitrile, the oscillator produced a 337 uHz linewidth over 3000 s, more than two orders narrower than in conventional zero-field NMR. This may facilitate precision measurements of J-coupling constants and allows distinguishing mixtures of molecules whose zero-field NMR spectra would otherwise be hard to separate. In addition, the combination of strongly coupled spin systems and programmable feedback turns the J-oscillator into a compact tabletop (and, eventually, chip-scale) platform for exploring nonlinear spin dynamics, including chaos, dynamical phase transitions, and perhaps time-crystal behavior. By uniting high-resolution spectroscopy and controllable quantum dynamics in a single, magnet-free setup, J-oscillators open new opportunities for applications where ultraprecise frequency references or molecular fingerprints are required.