The University of Sydney
Talk given by visitor Virginia Frey
Optimally band-limited controls for simultaneous multi-axis quantum sensing
The extreme fragility of quantum systems makes them ideally suited for sensing applications such as magnetometry, biological imaging, and noise characterization for quantum computing. However, interpreting the output signal of a qubit-based sensor is generally complicated by background clutter arising from both out-of-band spectral leakage, as well as ambiguity in signal origin when the sensor is operated with imperfect control.
Here we present and experimentally demonstrate a sensing protocol based on the optimally band-limited Slepian functions. Slepian controls linearize the sensor response, provide provably optimal narrowband sensing of an ambient dephasing term coupling to the sensor, and permit isolation of the target signal from contributions coupling via other Hamiltonian terms. We employ these techniques to perform efficient experimental reconstruction of a mixed dephasing spectrum, composed of a broadband 1/f-type spectrum with discrete spurs. Experiments using a single trapped ion demonstrate the relevant spectral properties of the controls for two different classes of signal through tomographic measurements. We then demonstrate the simultaneous reconstruction of two overlapping dephasing and control noise spectra from a single set of measurements, in a setting where the two spectra contribute equally to the overall sensor response. Our approach thus provides a direct means to augment quantum sensor performance in the presence of both a complex broadband environment and additional interference terms such as imperfect control signals.
- V. Frey, L. M. Norris, D. Lucarelli, M.J. Biercuk and L. Viola: ”Optimally band-limited controls for simultaneous multi-axis quantum sensing”, In preparation.
- L. M. Norris, D. Lucarelli, V. Frey, S. Mavadia, M.J. Biercuk and L. Viola: ”Optimally band-limited spectroscopy of control noise using a qubit sensor”, PRA98, 032315 (2018)
- V. Frey, S. Mavadia, L. M. Norris, D. Lucarelli, L. Viola and M.J.Biercuk: ”Application of optimal band-limited control protocols to quantum noise sensing”, Nature Communications 8 2189 (2017)