2024
[5] Detecting and Focusing on a Nonlinear Target in a Complex Medium
ArXivGoïcoechea, Antton; Hüpfl, Jakob; Rotter, Stefan; Sarrazin, François; Davy, Matthieu
arXiv.2407.07932, 2024.
@misc{goïcoechea2024detectingfocusingnonlineartarget,
title = {Detecting and Focusing on a Nonlinear Target in a Complex Medium},
author = {Antton Goïcoechea and Jakob Hüpfl and Stefan Rotter and François Sarrazin and Matthieu Davy},
url = {https://doi.org/10.48550/arXiv.2407.07932, ArXiv link},
year = {2024},
date = {2024-07-10},
urldate = {2024-07-10},
abstract = {Wavefront shaping techniques allow waves to be focused on a diffraction-limited target deep inside disordered media. To identify the target position, a guidestar is required that typically emits a frequency-shifted signal. Here we present a noninvasive matrix approach operating at a single frequency only, based on the variation of the field scattered by a nonlinear target illuminated at two incident powers. The local perturbation induced by the nonlinearity serves as a guide for identifying optimal incident wavefronts. We demonstrate maximal focusing on electronic devices embedded in chaotic microwave cavities and extend our approach to temporal signals. Finally, we exploit the programmability offered by reconfigurable smart surfaces to enhance the intensity delivered to a nonlinear target. Our results pave the way for deep imaging protocols that use any type of nonlinearity as feedback, requiring only the measurement of a monochromatic scattering matrix.},
howpublished = {arXiv.2407.07932},
type = {preprint},
keywords = {},
pubstate = {published},
tppubtype = {misc}
}
Wavefront shaping techniques allow waves to be focused on a diffraction-limited target deep inside disordered media. To identify the target position, a guidestar is required that typically emits a frequency-shifted signal. Here we present a noninvasive matrix approach operating at a single frequency only, based on the variation of the field scattered by a nonlinear target illuminated at two incident powers. The local perturbation induced by the nonlinearity serves as a guide for identifying optimal incident wavefronts. We demonstrate maximal focusing on electronic devices embedded in chaotic microwave cavities and extend our approach to temporal signals. Finally, we exploit the programmability offered by reconfigurable smart surfaces to enhance the intensity delivered to a nonlinear target. Our results pave the way for deep imaging protocols that use any type of nonlinearity as feedback, requiring only the measurement of a monochromatic scattering matrix.
[4] Continuity Equation for the Flow of Fisher Information in Wave Scattering
Nature PhysicsNews & ViewsHüpfl, Jakob; Russo, Felix; Rachbauer, Lukas M; Bouchet, Dorian; Lu, Junjie; Kuhl, Ulrich; Rotter, Stefan
In: Nature Physics, 2024.
@article{hüpfl2024continuity,
title = {Continuity Equation for the Flow of Fisher Information in Wave Scattering},
author = {Jakob Hüpfl and Felix Russo and Lukas M Rachbauer and Dorian Bouchet and Junjie Lu and Ulrich Kuhl and Stefan Rotter},
url = {https://doi.org/10.1038/s41567-024-02519-8, Nature Physics article
https://www.nature.com/articles/s41567-024-02550-9, News & Views
https://doi.org/10.48550/arXiv.2309.00010, ArXiv link},
year = {2024},
date = {2024-06-10},
urldate = {2024-06-10},
journal = {Nature Physics},
abstract = {Using waves to explore our environment is a widely used paradigm, ranging from seismology to radar technology, and from biomedical imaging to precision measurements. In all these fields, the central aim is to gather as much information as possible about an object of interest by sending a probing wave at it and processing the information delivered back to a detector. Here we demonstrate that an electromagnetic wave scattered at an object carries locally defined and conserved information about all of the object’s constitutive parameters. Specifically, we introduce the density and flux of Fisher information for general types of wave fields and identify the corresponding sources and sinks of information through which all these new quantities satisfy a fundamental continuity equation. We experimentally verify our theoretical predictions by studying a movable object embedded in a disordered environment and by measuring the corresponding Fisher information flux at microwave frequencies. Our results improve the understanding of the generation and propagation of information and open up possibilities for tracking and designing the flow of information even in complex environments.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Using waves to explore our environment is a widely used paradigm, ranging from seismology to radar technology, and from biomedical imaging to precision measurements. In all these fields, the central aim is to gather as much information as possible about an object of interest by sending a probing wave at it and processing the information delivered back to a detector. Here we demonstrate that an electromagnetic wave scattered at an object carries locally defined and conserved information about all of the object’s constitutive parameters. Specifically, we introduce the density and flux of Fisher information for general types of wave fields and identify the corresponding sources and sinks of information through which all these new quantities satisfy a fundamental continuity equation. We experimentally verify our theoretical predictions by studying a movable object embedded in a disordered environment and by measuring the corresponding Fisher information flux at microwave frequencies. Our results improve the understanding of the generation and propagation of information and open up possibilities for tracking and designing the flow of information even in complex environments.
[3] A Photonic Floquet Scattering Matrix for Wavefront-Shaping in Time-Periodic Media
PRAGlobosits, David; Hüpfl, Jakob; Rotter, Stefan
In: Phys. Rev. A, vol. 110, no. 5, pp. 053515, 2024.
@article{globosits2024photonic,
title = {A Photonic Floquet Scattering Matrix for Wavefront-Shaping in Time-Periodic Media},
author = {David Globosits and Jakob Hüpfl and Stefan Rotter},
url = {https://link.aps.org/doi/10.1103/PhysRevA.110.053515, PRA link
https://doi.org/10.48550/arXiv.2403.19311, ArXiv link},
doi = {10.1103/PhysRevA.110.053515},
year = {2024},
date = {2024-03-28},
urldate = {2024-03-28},
journal = {Phys. Rev. A},
volume = {110},
number = {5},
pages = {053515},
abstract = {The physics of waves in time-varying media provides numerous opportunities for wave control that are unattainable with static media. In particular, Floquet systems with a periodic time modulation are currently of considerable interest. Here, we demonstrate how the scattering properties of a finite Floquet medium can be correctly described by a static Floquet scattering matrix, which satisfies a pseudo-unitary relation. This algebraic property is a consequence of the conservation of wave action for which we formulate here a continuity equation. Using this Floquet scattering matrix, we further demonstrate how it can be used to generalize also the seminal Wigner-Smith operator from static to Floquet systems. The eigenstates of the corresponding Floquet Wigner-Smith matrix are shown to be light pulses that are optimally shaped both in their spatial and temporal degrees of freedom for the optical micromanipulation of time-varying media. },
type = {preprint},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The physics of waves in time-varying media provides numerous opportunities for wave control that are unattainable with static media. In particular, Floquet systems with a periodic time modulation are currently of considerable interest. Here, we demonstrate how the scattering properties of a finite Floquet medium can be correctly described by a static Floquet scattering matrix, which satisfies a pseudo-unitary relation. This algebraic property is a consequence of the conservation of wave action for which we formulate here a continuity equation. Using this Floquet scattering matrix, we further demonstrate how it can be used to generalize also the seminal Wigner-Smith operator from static to Floquet systems. The eigenstates of the corresponding Floquet Wigner-Smith matrix are shown to be light pulses that are optimally shaped both in their spatial and temporal degrees of freedom for the optical micromanipulation of time-varying media.
2023
[2] Optimal Cooling of Multiple Levitated Particles through Far-Field Wavefront Shaping
PRLFeatured in PhysicsHüpfl, Jakob; Bachelard, Nicolas; Kaczvinszki, Markus; Horodynski, Michael; Kühmayer, Matthias; Rotter, Stefan
In: Phys. Rev. Lett., vol. 130, no. 8, 2023, ISSN: 1079-7114.
@article{Hüpfl2023b,
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.doi.org/10.1103/physrevlett.130.083203, Article link
https://arxiv.org/abs/2103.12592, ArXiv link
https://physics.aps.org/articles/v16/s30, Physics Magazine},
issn = {1079-7114},
year = {2023},
date = {2023-02-22},
urldate = {2023-02-22},
journal = {Phys. Rev. Lett.},
volume = {130},
number = {8},
publisher = {American Physical Society (APS)},
abstract = {Light forces can be harnessed to levitate mesoscopic objects and cool them down toward their motional quantum ground state. Roadblocks on the way to scale up levitation from a single to multiple particles in close proximity are the requirements to constantly monitor the particles’ positions as well as to engineer light fields that react fast and appropriately to their movements. Here, we present an approach that solves both problems at once. By exploiting the information stored in a time-dependent scattering matrix, we introduce a formalism enabling the identification of spatially modulated wavefronts, which simultaneously cool down multiple objects of arbitrary shapes. An experimental implementation is suggested based on stroboscopic scattering-matrix measurements and time-adaptive injections of modulated light fields.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Light forces can be harnessed to levitate mesoscopic objects and cool them down toward their motional quantum ground state. Roadblocks on the way to scale up levitation from a single to multiple particles in close proximity are the requirements to constantly monitor the particles’ positions as well as to engineer light fields that react fast and appropriately to their movements. Here, we present an approach that solves both problems at once. By exploiting the information stored in a time-dependent scattering matrix, we introduce a formalism enabling the identification of spatially modulated wavefronts, which simultaneously cool down multiple objects of arbitrary shapes. An experimental implementation is suggested based on stroboscopic scattering-matrix measurements and time-adaptive injections of modulated light fields.
[1] Optimal cooling of multiple levitated particles: Theory of far-field wavefront shaping
PRAEditors' suggestionFeatured in PhysicsHüpfl, Jakob; Bachelard, Nicolas; Kaczvinszki, Markus; Horodynski, Michael; Kühmayer, Matthias; Rotter, Stefan
In: Phys. Rev. A, vol. 107, no. 2, 2023, ISSN: 2469-9934.
@article{Hüpfl2023,
title = {Optimal cooling of multiple levitated particles: Theory of 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.doi.org/10.1103/physreva.107.023112, Article link
https://arxiv.org/abs/2206.01046, ArXiv link
https://physics.aps.org/articles/v16/s30, Physics Magazine},
issn = {2469-9934},
year = {2023},
date = {2023-02-22},
urldate = {2023-02-22},
journal = {Phys. Rev. A},
volume = {107},
number = {2},
publisher = {American Physical Society (APS)},
abstract = {The opportunity to manipulate small-scale objects pushes us to the limits of our understanding of physics. Particularly promising in this regard is the interdisciplinary field of levitation, in which light fields can be harnessed to isolate nanoparticles from their environment by levitating them optically. When cooled towards their motional quantum ground state, levitated systems offer the tantalizing prospect of displaying mesoscopic quantum properties. While the interest in levitation has so far been focused mainly on manipulating individual objects with simple shapes, the field is currently moving towards the control of more complex structures, such as those featuring multiple particles or different degrees of freedom. Unfortunately, current cooling techniques are mostly designed for single objects and thus cannot easily be multiplexed to address such coupled many-body systems. Here we present an approach based on the spatial modulation of light in the far field to cool multiple nano-objects in parallel. Our procedure is based on the experimentally measurable scattering matrix and on its changes with time. We demonstrate how to compose from these ingredients a linear energy-shift operator, whose eigenstates are identified as the incoming wavefronts that implement the most efficient cooling of complex moving ensembles of levitated particles. Submitted in parallel with Hüpfl et al. [Phys. Rev. Lett. 130, 083203 (2023)], this article provides a theoretical and numerical study of the expected cooling performance as well as of the robustness of the method against environmental parameters.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The opportunity to manipulate small-scale objects pushes us to the limits of our understanding of physics. Particularly promising in this regard is the interdisciplinary field of levitation, in which light fields can be harnessed to isolate nanoparticles from their environment by levitating them optically. When cooled towards their motional quantum ground state, levitated systems offer the tantalizing prospect of displaying mesoscopic quantum properties. While the interest in levitation has so far been focused mainly on manipulating individual objects with simple shapes, the field is currently moving towards the control of more complex structures, such as those featuring multiple particles or different degrees of freedom. Unfortunately, current cooling techniques are mostly designed for single objects and thus cannot easily be multiplexed to address such coupled many-body systems. Here we present an approach based on the spatial modulation of light in the far field to cool multiple nano-objects in parallel. Our procedure is based on the experimentally measurable scattering matrix and on its changes with time. We demonstrate how to compose from these ingredients a linear energy-shift operator, whose eigenstates are identified as the incoming wavefronts that implement the most efficient cooling of complex moving ensembles of levitated particles. Submitted in parallel with Hüpfl et al. [Phys. Rev. Lett. 130, 083203 (2023)], this article provides a theoretical and numerical study of the expected cooling performance as well as of the robustness of the method against environmental parameters.