Talks and Posters

@misc{nokey,

title = {Wavefront shaping in nonlinear and time-periodic media: Focusing and Micromanipulation},

author = {Jakob Hüpfl and Antton Goïcoechea and David Globosits and François Sarrazin and Matthieu Davy and Stefan Rotter},

url = {https://aesconference.org/AES25/index.php/AES/index},

year  = {2025},

date = {2025-07-01},

abstract = {Wavefront shaping enables focusing and optical micromanipulation of targets in disordered media, but typically requires additional system information such as a guide star. We present two approaches that circumvent this requirement: one exploits the nonlinear responses for noninvasive focusing, the other applies Floquet theory to time-periodic wavefront control.},

note = {Invited speaker at The 11th International Conference on Antennas and Electromagnetic Systems (AES2025)},

keywords = {},

pubstate = {published},

tppubtype = {presentation}

}

@misc{AES2024,

title = {Connecting antenna and diffraction theory with the radiation of Fisher information in scattering experiments},

author = {Jakob Hüpfl and Felix Russo and Lukas M Rachbauer and Dorian Bouchet and Junjie Lu and Ulrich Kuhl and Stefan Rotter},

url = {https://aesconference.org/AES24/index.php/AES/index},

year  = {2024},

date = {2024-06-26},

abstract = {Electromagnetic waves are used over a wide range of disciplines to precisely estimate a target’s properties. We explore how these waves interact with matter to gather Fisher information from an object of interest and transmit it to the far-field. By identifying information sources, we build a connection to antenna theory.},

note = {Invited speaker at The 10th International Conference on Antennas and Electromagnetic Systems (AES 2024).},

keywords = {},

pubstate = {published},

tppubtype = {presentation}

}

@misc{EOSAM2023,

title = {Optimal Cooling of Multiple Levitated Particles through Far-Field Wavefront Shaping},

author = {Jakob Hüpfl and Nicolas Bachelard and Markus Kaczvinszki and Michael Horodynski and Matthias Kühmayer and Stefan Rotter},

url = {https://www.europeanoptics.org/pages/events/eosam-2023/topical-meetings-and-sessions/nanophotonics.html},

year  = {2023},

date = {2023-09-13},

urldate = {2023-09-13},

abstract = {Particles on the nano- to micrometer scale can be levitated and cooled down towards their motional ground state using optical forces. A major challenge in the field of levitation consists in extending existing methods to many particles. This would allow for the entanglement of mesoscopic objects or could provide a platform to test many-body quantum effects at the mesoscale. Indeed, a significant roadblock so far has been the requirement to monitor the particles' many degrees of freedom simultaneously and to engineer complex light fields to respond to their motion in real time. We solve both of these problems by introducing and computationally verifying a novel multi-particle cooling approach using a generalization of the Wigner-Smith time-delay operator [Phys.Rev. Lett. 130,083203 (2023)]. For electromagnetic fields we connect the eigenvalues of this operator with the energy shift the corresponding fields induce in the particles. Through this, we can identify spatially modulated wave-fronts creating near-field patterns that optimally counteract the motion of multiple particles in parallel. Remarkably, our approach exhibits excellent scaling properties with the number of particles, and maintains its validity in complex scattering environments. These results suggest an experimental implementation, where continuously shaped wave-fronts efficiently cool an ensemble of levitated objects.},

note = {Invited speaker at European Optical Society Annual Meeting (EOSAM 2023,  TOM4- Nanophotonics).},

keywords = {},

pubstate = {published},

tppubtype = {presentation}

}

@misc{HeraeusSeminar2023,

title = {Multi-Particle Active Feedback Cooling Using Shaped Wave-Fronts},

author = {Jakob Hüpfl and Nicolas Bachelard and Markus Kaczvinszki and Michael Horodynski and Matthias Kühmayer and Stefan Rotter},

url = {https://www.we-heraeus-stiftung.de/veranstaltungen/exploiting-levitated-particles-in-the-quantum-regime/program/},

year  = {2023},

date = {2023-09-07},

abstract = {Levitated particles offer a unique and controlled platform for precise investigations of various physical effects while minimizing external influences. The potential to perform high-precision force sensing experiments and explore quantum phenomena using cooled particles has emerged as an intriguing possibility. However, to fully unlock the complexity and capabilities of these systems, the simultaneous trapping and cooling of a large number of particles is crucial. This poses a challenge as existing techniques rely on controlled environments, making the scaling up to larger systems challenging due to intricate interactions between individual particles. Here, we propose a novel multi-particle cooling approach utilizing a generalization of the Wigner-Smith time-delay operator [1,2]. By establishing a connection between the eigenvalues of this operator and system changes, we leverage advancements in spatial light modulators to introduce an active feedback cooling scheme. Our scheme utilizes far-field information from the electromagnetic field to generate a sequence of customized input wave-fronts, which simultaneously cool the translational and rotational center-of-mass motion for all particles in parallel. Remarkably, our approach decouples the degrees of freedom of the field from those of the particles, naturally leading to good scaling properties. To validate the scalability of our approach, we conducted numerical simulations demonstrating its effectiveness across a wide range of particle numbers, sizes, and shapes. Based on these findings, we propose an experimental implementation wherein continuously shaped wave-fronts cool an ensemble of levitated objects, with the goal to observe and analyze the cooling effects in a practical setting using state of the art equipment.



References

[1] J. Hüpfl, N. Bachelard, M. Kaczvinszki, M. Horodynski, M. Kühmayer, S.

Rotter, Phys. Rev. Lett. 130, 083203(2023)

[2] J. Hüpfl, N. Bachelard, M. Kaczvinszki, M. Horodynski, M. Kühmayer, S.

Rotter, Phys. Rev. A. 107, 023112(2023)},

note = {Hot topic talk at the 794. WE-Heraeus-Seminar (Exploiting Levitated Particles in the Quantum Regime).},

keywords = {},

pubstate = {published},

tppubtype = {presentation}

}

@misc{Sciencecamp2022,

title = {Cooling levitated mesoscopic particles through wave-front shaping in the far-field},

author = {Jakob Hüpfl and Nicolas Bachelard and Markus Kaczvinszki and Michael Horodynski and Matthias Kühmayer and Stefan Rotter},

url = {https://www.sciencecamp.eu/wp-content/uploads/2022/07/Science_Camp_2022_book_of_abstracts_v2.pdf},

year  = {2022},

date = {2022-08-04},

urldate = {2022-08-04},

abstract = {Particles on the nano- to micrometer scale can be levitated and cooled down towards their motional ground state using optical forces [1]. A major challenge in the field of levitation consists in extending the methods to many particles. This would allow for the entanglement of mesoscopic objects or could provide a platform to test many-body quantum effects at the mesoscale. Indeed, a significant roadblock so far has been the requirement to monitor the particles' many degrees of freedom simultaneously and to engineer complex light fields to respond to their motion in real time. Here[2,3], we solve both of these problems by introducing and computationally verifying a novel multi-particle cooling approach using a generalization of the Wigner-Smith time-delay operator [4-6]. For macroscopic electromagnetic fields we connect the eigenvalues of this operator with the energy shift the corresponding fields induce in the particles. Through this, we can identify spatially modulated wave-fronts that can optimally counteract the motion of multiple particles in parallel. Remarkably, our approach only uses far-field information and decouples the degrees of freedom of the light field from those of the particles, naturally leading to good scaling properties. We can thus propose an experimental implementation, where wave-fronts are constructed in real time to cool an ensemble of levitated objects. 

[1] U. Delić, M. Reisenbauer, K. Dare, D. Grass, V. Vuletić, N. Kiesel, M. Aspelmeyer, Science 367, 892(2020).

[2] M. Kaczvinszki, N. Bachelard, J. Hüpfl, M. Horodynski, M. Kühmayer, S. Rotter, arXiv:2103.12592(under review at Physical Review Letters)

[3] J. Hüpfl, N. Bachelard, M. Kaczvinszki, M. Horodynski, M. Kühmayer, S. Rotter, Manuscript in preparation

[4] E. P. Wigner, Phys. Rev. 98, 145(1955).

[5] F. T. Smith, Phys. Rev. 118, 349(1960).

[6] M. Horodynski, M. Kühmayer, A. Brandstötter, K. Pichler, Y. V. Fyodorov, U. Kuhl, S. Rotter, Nature Photonics 14, 149(2020).},

note = {Contributed talk at Complex Nanophotonics Science Camp 2022.},

keywords = {},

pubstate = {published},

tppubtype = {presentation}

}