Quantum optics seminar
Control, sensing and gravitational coupling of milligram pendulums: towards interfacing quantum and gravity
Prof. Onur Hosten
Institute of Science and Technology Austria
Abstract
Zoom link: https://us02web.zoom.us/j/84734133182?pwd=IeJFtK1DcJEZA389D1vkxjnYzLjakq.1
Abstract:
Can we test the quantum mechanical nature of gravitational fields? Milligram-scale optomechanical experiments present a frontier for bridging quantum mechanics and gravitational physics by aiming to strike a balance between 1) making gravitational couplings of the controlled objects dominant and 2) making the motions of these objects quantum noise dominated. Required systems necessitate low-frequency dynamics that is typically considered quantum-unfriendly, but seems to be needed to achieve a large figure-of-merit in the problem, quantifying the ability to generate quantum entanglement gravitationally.
In this talk, I will first focus on our 1-milligram suspended torsional pendulum operating at 18 Hz, and the successful laser cooling of its motion to 240~microkelvins. I will elucidate the resulting boost in the quantum coherence length of this pendulum [1]. I will give an update on the second generation of this optical-lever based experiment and outline a path towards gravitational entanglement utilizing our zig-zag optical cavities [2] to boost the interactions of light and torsional pendulums. I will conclude with our ongoing effort of achieving gravitationally-limited coupling between two free running ~1 milligram pendulums – aiming to push observable inter-particle gravitational couplings down by 3 orders of magnitude.
References
[1] S. Agafonova, …, O. Hosten, “One-milligram torsional pendulum toward experiments at the quantum-gravity interface. Commun Phys 9, 80 (2026)”
[2] S. Agafonova, …, O. Hosten, “A zigzag optical cavity for sensing and controlling torsional motion”, Phys. Rev. Research 6, 013141. (2024)
Abstract:
Can we test the quantum mechanical nature of gravitational fields? Milligram-scale optomechanical experiments present a frontier for bridging quantum mechanics and gravitational physics by aiming to strike a balance between 1) making gravitational couplings of the controlled objects dominant and 2) making the motions of these objects quantum noise dominated. Required systems necessitate low-frequency dynamics that is typically considered quantum-unfriendly, but seems to be needed to achieve a large figure-of-merit in the problem, quantifying the ability to generate quantum entanglement gravitationally.
In this talk, I will first focus on our 1-milligram suspended torsional pendulum operating at 18 Hz, and the successful laser cooling of its motion to 240~microkelvins. I will elucidate the resulting boost in the quantum coherence length of this pendulum [1]. I will give an update on the second generation of this optical-lever based experiment and outline a path towards gravitational entanglement utilizing our zig-zag optical cavities [2] to boost the interactions of light and torsional pendulums. I will conclude with our ongoing effort of achieving gravitationally-limited coupling between two free running ~1 milligram pendulums – aiming to push observable inter-particle gravitational couplings down by 3 orders of magnitude.
References
[1] S. Agafonova, …, O. Hosten, “One-milligram torsional pendulum toward experiments at the quantum-gravity interface. Commun Phys 9, 80 (2026)”
[2] S. Agafonova, …, O. Hosten, “A zigzag optical cavity for sensing and controlling torsional motion”, Phys. Rev. Research 6, 013141. (2024)