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Enhanced Resolution in Nanoscale NMR via Quantum Sensing with Pulses of Finite Duration

MetadataDetails
Publication Date2017-05-01
JournalUCL Discovery (University College London)
AuthorsJ. E. Lang, J. Casanova, Z.-Y. Wang, Martin B. Plenio, T. S. Monteiro
InstitutionsUniversitƤt Ulm, University College London
Citations18

The nitrogen-vacancy (N-V) color center in diamond is an enormously important platform for the
\ndevelopment of quantum sensors, including for single-spin and single-molecule NMR. Detection of weak
\nsingle-spin signals is greatly enhanced by repeated sequences of microwave pulses; in these dynamicaldecoupling
\ntechniques, the key control parameters swept in the experiment are the time intervals, Ļ„,
\nbetween pulses. Here, we show that, in fact, the pulse duration tp offers a powerful additional control
\nparameter. While a non-negligible tp was previously considered simply a source of experimental error, we
\nelucidate here the underlying quantum dynamics: we identify a landscape of quantum-state crossings which
\nare usually inactive (closed) but may be controllably activated (opened) by adjusting tp from zero. We
\nidentify these crossings with recently observed but unexpected dips (so-called spurious dips) seen in the
\nquantum coherence of the N-V spin. With this new understanding, both the position and the strength of
\nthese sharp features may be accurately controlled; they coexist with the usual broader coherence dips of
\nshort-duration microwave pulses, but their sharpness allows for higher-resolution spectroscopy with
\nquantum diamond sensors, or their analogs.