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David Grass

Research Associate
Chemistry

Selected Publications


Non-destructive three-dimensional imaging of artificially degraded CdS paints by pump-probe microscopy

Journal Article JPhys Photonics · April 1, 2024 Cadmium sulfide (CdS) pigments have degraded in several well-known artworks, but the influence of pigment properties and environmental conditions on the degradation process have yet to be fully understood. Traditional non-destructive analysis techniques pr ... Full text Cite

Contrast mechanisms in pump-probe microscopy of melanin.

Journal Article Opt Express · August 29, 2022 Pump-probe microscopy of melanin in tumors has been proposed to improve diagnosis of malignant melanoma, based on the hypothesis that aggressive cancers disaggregate melanin structure. However, measured signals of melanin are complex superpositions of mult ... Full text Link to item Cite

Nonequilibrium Control of Thermal and Mechanical Changes in a Levitated System.

Journal Article Physical review letters · February 2022 Fluctuation theorems are fundamental extensions of the second law of thermodynamics for small nonequilibrium systems. While work and heat are equally important forms of energy exchange, fluctuation relations have not been experimentally assessed for the ge ... Full text Cite

Nonequilibrium control of thermal and mechanical changes in a levitated system

Journal Article Phys. Rev. Lett. · March 19, 2021 Fluctuation theorems are fundamental extensions of the second law of thermodynamics for small nonequilibrium systems. While work and heat are equally important forms of energy exchange, fluctuation relations have not been experimentally assessed for the ge ... Link to item Cite

Beyond intensity modulation: new approaches to pump-probe microscopy.

Journal Article Optics letters · March 2021 Pump-probe microscopy is an emerging nonlinear imaging technique based on high repetition rate lasers and fast intensity modulation. Here, we present new methods for pump-probe microscopy that keep the beam intensity constant and instead modulate the inter ... Full text Cite

Low-cost measurement of face mask efficacy for filtering expelled droplets during speech.

Journal Article Sci Adv · September 2020 Mandates for mask use in public during the recent coronavirus disease 2019 (COVID-19) pandemic, worsened by global shortage of commercial supplies, have led to widespread use of homemade masks and mask alternatives. It is assumed that wearing such masks re ... Full text Link to item Cite

Low-cost measurement of facemask efficacy for filtering expelled droplets during speech

Journal Article · June 22, 2020 AbstractMandates for mask use in public during the recent COVID-19 pandemic, worsened by global shortage of commercial supplies, have led to widespread use of homemade masks and mask alternatives. It is assumed that wearing ... Full text Cite

Levitated cavity optomechanics in high vacuum

Journal Article Quantum Science and Technology · March 1, 2020 We report dispersive coupling of an optically trapped nanoparticle to the field of a Fabry-Perot cavity in high vacuum. We demonstrate nanometer-level control in positioning the particle with respect to the cavity field, which allows access to linear, quad ... Full text Cite

Thermodynamics of continuous non-Markovian feedback control.

Journal Article Nature communications · March 2020 Feedback control mechanisms are ubiquitous in science and technology, and play an essential role in regulating physical, biological and engineering systems. The standard second law of thermodynamics does not hold in the presence of measurement and feedback ... Full text Cite

Cooling of a levitated nanoparticle to the motional quantum ground state.

Journal Article Science (New York, N.Y.) · February 2020 Quantum control of complex objects in the regime of large size and mass provides opportunities for sensing applications and tests of fundamental physics. The realization of such extreme quantum states of matter remains a major challenge. We demonstrate a q ... Full text Cite

Cavity Cooling of a Levitated Nanosphere by Coherent Scattering.

Journal Article Physical review letters · March 2019 We report three-dimensional (3D) cooling of a levitated nanoparticle inside an optical cavity. The cooling mechanism is provided by cavity-enhanced coherent scattering off an optical tweezer. The observed 3D dynamics and cooling rates are as theoretically ... Full text Cite

Nanophotonic near-field levitated optomechanics

Conference Optics InfoBase Conference Papers · January 1, 2019 Optical levitation of dielectric particles is a promising platform for room temperature quantum optomechanics. The challenge is to control the mechanical motion at the Heisenberg uncertainty limit. We present a nanophotonic interface enabling strong and ef ... Full text Cite

Near-field coupling of a levitated nanoparticle to a photonic crystal cavity

Journal Article Optica · December 20, 2018 Quantum control of levitated dielectric particles is an emerging subject in quantum optomechanics. A major challenge is to efficiently measure and manipulate the particle’s motion at the Heisenberg uncertainty limit. Here we present a nanophotonic interfac ... Full text Cite

Optical trapping and control of nanoparticles inside evacuated hollow core photonic crystal fibers

Journal Article Applied Physics Letters · May 30, 2016 We demonstrate an optical conveyor belt for levitated nanoparticles over several centimeters inside both air-filled and evacuated hollow-core photonic crystal fibers (HCPCF). Detection of the transmitted light field allows three-dimensional read-out of the ... Full text Cite

Cavity cooling of an optically levitated submicron particle.

Journal Article Proceedings of the National Academy of Sciences of the United States of America · August 2013 The coupling of a levitated submicron particle and an optical cavity field promises access to a unique parameter regime both for macroscopic quantum experiments and for high-precision force sensing. We report a demonstration of such controlled interactions ... Full text Cite