A tunable feedback-controlled magnetic trap for a magnet in free fall

Fuente: arXiv
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Hauptverfasser: Xu, Changhao, Heidt, Alexander, Nematollahi, Mohammadreza, Lotz, Christoph, Rasel, Ernst Maria, Liu, Yan, Ji, Wei, Budker, Dmitry
Format: Preprint
Veröffentlicht: 2026
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author Xu, Changhao
Heidt, Alexander
Nematollahi, Mohammadreza
Lotz, Christoph
Rasel, Ernst Maria
Liu, Yan
Ji, Wei
Budker, Dmitry
author_facet Xu, Changhao
Heidt, Alexander
Nematollahi, Mohammadreza
Lotz, Christoph
Rasel, Ernst Maria
Liu, Yan
Ji, Wei
Budker, Dmitry
contents Ferromagnets in free space are predicted to exhibit pure Larmor precession at near-zero magnetic fields and provide exceptional sensitivity for magnetometry and gyroscopy. Notably, pure Larmor precession has not been observed in a macroscopic ferromagnetic particle, despite its fundamental importance and potential for probing relativistic effects and dark-matter interactions. Realizing such dynamics requires true free fall to eliminate clamping losses and trap-induced systematics. A central challenge is designing a tunable trap that is weak enough to permit near-free evolution yet robust enough to withstand the disturbances of launch and release. Here, we propose and demonstrate a novel master proportional-integral-differential magnetic trap (MPIDMT) combining a PID-controlled coil system with a master control coil system. Implemented in the third-generation drop tower - Einstein-Elevator, during the microgravity phase the system stably levitates a ferromagnetic particle against shock accelerations up to 1.5 g and resolves its motion in both a low-field (0.4 g) configuration and in pure free fall. These results represent a key step toward free-fall ferromagnetic magnetometry, the long-sought direct observation of macroscopic Larmor precession, and future space-based experiments.
format Preprint
id arxiv_https___arxiv_org_abs_2606_01056
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A tunable feedback-controlled magnetic trap for a magnet in free fall
Xu, Changhao
Heidt, Alexander
Nematollahi, Mohammadreza
Lotz, Christoph
Rasel, Ernst Maria
Liu, Yan
Ji, Wei
Budker, Dmitry
Atomic Physics
Applied Physics
Instrumentation and Detectors
Quantum Physics
Ferromagnets in free space are predicted to exhibit pure Larmor precession at near-zero magnetic fields and provide exceptional sensitivity for magnetometry and gyroscopy. Notably, pure Larmor precession has not been observed in a macroscopic ferromagnetic particle, despite its fundamental importance and potential for probing relativistic effects and dark-matter interactions. Realizing such dynamics requires true free fall to eliminate clamping losses and trap-induced systematics. A central challenge is designing a tunable trap that is weak enough to permit near-free evolution yet robust enough to withstand the disturbances of launch and release. Here, we propose and demonstrate a novel master proportional-integral-differential magnetic trap (MPIDMT) combining a PID-controlled coil system with a master control coil system. Implemented in the third-generation drop tower - Einstein-Elevator, during the microgravity phase the system stably levitates a ferromagnetic particle against shock accelerations up to 1.5 g and resolves its motion in both a low-field (0.4 g) configuration and in pure free fall. These results represent a key step toward free-fall ferromagnetic magnetometry, the long-sought direct observation of macroscopic Larmor precession, and future space-based experiments.
title A tunable feedback-controlled magnetic trap for a magnet in free fall
topic Atomic Physics
Applied Physics
Instrumentation and Detectors
Quantum Physics
url https://arxiv.org/abs/2606.01056