One of the prime features of quantum systems strongly driven by external time-periodic fields is the subharmonic response with integer multiples of the drive period kTd. Here we demonstrate experimentally based on a careful theoretical analysis period doubling and higher multiplicities (k=2,…5) for one of the most fundamental systems, namely, an individual spin-1/2. Realized as a nitrogen vacancy center in diamond, the particular coherence properties under ambient conditions, strong field sensitivity, and optical addressability allow to monitor coherent k-tupling oscillations over a broad set of driving parameters in the vicinity of the ideal manifolds. We verify an enhanced sensitivity within this domain which provides new means for improved sensing protocols.
@article{arxiv.2507.18387,
title = {Observation of period doubling and higher multiplicities in a driven single-spin system},
author = {Dhruv Deshmukh and Raúl B. González and Roberto Sailer and Fedor Jelezko and Ressa S. Said and Joachim Ankerhold},
journal= {arXiv preprint arXiv:2507.18387},
year = {2025}
}