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Subject: search.filters.subject.530Institute: search.filters.UBSInstitut.Institut für Theoretische Physik IStart date: 2025End date: 2025Author: search.filters.author.Lutz, Eric

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    Electrostatic all-passive force clamping of charged nanoparticles
    (2025) Tuna, Yazgan; Al-Hiyasat, Amer; Kashkanova, Anna D.; Dechant, Andreas; Lutz, Eric; Sandoghdar, Vahid
    In the past decades, many techniques have been explored for trapping microscopic and nanoscopic objects, but the investigation of nano-objects under arbitrary forces and conditions remains nontrivial. One fundamental case concerns the motion of a particle under a constant force, known as force clamping . Here, we employ metallic nanoribbons embedded in a glass substrate in a capacitor configuration to generate a constant electric field on a charged nanoparticle in a water-filled glass nanochannel. We estimate the force fields from Brownian trajectories over several micrometers and confirm the constant behavior of the forces both numerically and experimentally. Furthermore, we manipulate the diffusion and relaxation times of the nanoparticles by tuning the charge density on the electrode. Our highly compact and controllable setting allows for the trapping and force-clamping of charged nanoparticles in a solution, providing a platform for investigating nanoscopic diffusion phenomena.
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    Noise-induced quantum synchronization with entangled oscillations
    (2025) Tao, Ziyu; Schmolke, Finn; Hu, Chang-Kang; Huang, Wenhui; Zhou, Yuxuan; Zhang, Jiawei; Chu, Ji; Zhang, Libo; Sun, Xuandong; Guo, Zechen; Niu, Jingjing; Weng, Wenle; Liu, Song; Zhong, Youpeng; Tan, Dian; Yu, Dapeng; Lutz, Eric
    Random fluctuations can lead to cooperative effects in complex systems. We here report the observation of noise-induced quantum synchronization in a chain of superconducting transmon qubits with nearest-neighbor interactions. The application of Gaussian white noise to a single site leads to synchronous oscillations in the entire chain. We show that the two synchronized end qubits are entangled, with nonzero concurrence, and that they belong to a class of generalized Bell states known as maximally entangled mixed states, whose entanglement cannot be increased by any global unitary. We further demonstrate the stability against frequency detuning of both synchronization and entanglement by determining the corresponding generalized Arnold tongue diagrams. Our results highlight the constructive influence of noise in a quantum many-body system, and initiate the exploration of collective synchronization effects with stronger than classical correlations.
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    Fundamental limits on nonequilibrium sensing
    (2025) Dechant, Andreas; Lutz, Eric
    The performance of equilibrium sensors is restricted by the laws of equilibrium thermodynamics. Here, we investigate the physical limits on nonequilibrium sensing in bipartite systems with both reciprocal and nonreciprocal couplings. We show that one of the subsystems, acting as a Maxwell demon, can significantly suppress the fluctuations of the other subsystem relative to its response to an external perturbation. The importance of nonreciprocal interactions for such negative violations of the fluctuation-dissipation relation to occur is identified. We further demonstrate that these violations can considerably improve the signal-to-noise ratio above its corresponding equilibrium value, allowing the subsystem to operate as an enhanced sensor. In addition, we find that the nonequilibrium signal-to-noise ratio of linear systems may be arbitrarily large at low frequencies after proper parameter optimization, even at a fixed overall amount of dissipation. These results indicate that highly accurate nonreciprocal sensors can be designed at a finite energetic cost.