Lykourgos Bougas

Search for Ultralight Scalar Dark Matter with Atomic Spectroscopy.

We report new limits on ultralight scalar dark matter (DM) with dilatonlike couplings to photons that can induce oscillations in the fine-structure constant α. Atomic dysprosium exhibits an electronic structure with two nearly degenerate levels whose energy splitting is sensitive to changes in α. Spectroscopy data for two isotopes of dysprosium over a two-year span are analyzed for coherent oscillations with angular frequencies below 1  rad s-1. No signal consistent with a DM coupling is identified, leading to new constraints on dilatonlike photon couplings over a wide mass range. Under the assumption that the scalar field comprises all of the DM, our limits on the coupling exceed those from equivalence-principle tests by up to 4 orders of magnitude for masses below 3×10(-18)  eV. Excess oscillatory power, inconsistent with fine-structure variation, is detected in a control channel, and is likely due to a systematic effect. Our atomic spectroscopy limits on DM are the first of their kind, and leave substantial room for improvement with state-of-the-art atomic clocks.

Microwave-free magnetometry with nitrogen-vacancy centers in diamond

We use magnetic-field-dependent features in the photoluminescence of negatively charged nitrogen-vacancy centers to measure magnetic fields without the use of microwaves. In particular, we present a magnetometer based on the level anti-crossing in the triplet ground state at 102.4 mT with a demonstrated noise floor of 6 nT/ Hz, limited by the intensity noise of the laser and the performance of the background-field power supply. The technique presented here can be useful in applications where the sensor is placed close to conductive materials, e.g., magnetic induction tomography or magnetic field mapping, and in remote-sensing applications since principally no electrical access is needed.

Miniature Cavity-Enhanced Diamond Magnetometer

We present a highly sensitive miniaturized cavity-enhanced room-temperature magnetic-field sensor based on nitrogen-vacancy (NV) centers in diamond. The magnetic resonance signal is detected by probing absorption on the 1042\,nm spin-singlet transition. To improve the absorptive signal the diamond is placed in an optical resonator. The device has a magnetic-field sensitivity of 28 pT/

Solution nuclear magnetic resonance spectroscopy on a nanostructured diamond chip

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Towards improved measurements of parity violation in atomic ytterbium

, a projected photon shot-noise-limited sensitivity of 22 pT/

On the Possibility of Miniature Diamond-Based Magnetometers Using Waveguide Geometries

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Nondestructive in-line sub-picomolar detection of magnetic nanoparticles in flowing complex fluids

and an estimated quantum projection-noise-limited sensitivity of 0.43 pT/

Quantitative measurements of non-covalent interactions with diamond based magnetic imaging

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Level anti-crossing magnetometry with color centers in diamond

with the sensing volume of

Measuring molecular parity nonconservation using nuclear-magnetic-resonance spectroscopy

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