Atomic Physics Seminars

Monday, November 29, 2021
4:00 PM
Physics Building, Room 204

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"Levitated Optomechanics and the Casimir Effect"

Professor Tongcang Li , Purdue University
[Host: Prof. Peter Schauss]

Optical tweezers provide a non-contact method to manipulate microscopic objects and have many potential applications in precision measurements. Recently, we developed an optically levitated Cavendish torsion balance for quantum-limited torque and force sensing [Phys. Rev. Lett., 121, 033603  (2018)]. We have optically levitated nanoparticles in a vacuum and driven them to rotate up to 300 billion rpm (5 GHz). Using a levitated nanoparticle in a vacuum, we demonstrated ultrasensitive torque detection with a sensitivity several orders higher than the former record [Nature Nanotechnology 15, 89 (2020)]. This system will be promising to study quantum friction, Casimir torque, and gravity at short distances.  We also propose and demonstrate a scheme to achieve strong coupling between multiple micromechanical oscillators with virtual photons, i.e., quantum vacuum fluctuations. Quantum field theory predicts that there are random fluctuations everywhere in a vacuum due to the zero-point energy. The quantum electromagnetic fluctuations can induce a measurable force between neutral objects, which is known as the Casimir effect. We have achieved non-reciprocal energy transfer between two mechanical resonators coupled by quantum vacuum fluctuations [arXiv:2102.12857].

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