Real-Time Observation of Charge-Spin Cooperative Dynamics Driven by a Nonequilibrium Phonon Environment

Kuroyama, Kazuyuki; Matsuo, Sadashige; Muramoto, Jo; Yabunaka, Shunsuke; Valentin, Sascha R.; Ludwig, Arne; Wieck, A. D.; Tokura, Y.; Tarucha, Seigo

doi:10.1103/physrevlett.129.095901

Cited by 4 publications

(1 citation statement)

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“…However, recent experimental studies have shed light on the emergence of nonequilibrium features in rapid and dynamic processes involving physical or biological systems. [56][57][58][59][60][61] These ultra-fast and transient processes occur within such short periods that the initial nonequilibrium state resulting from system-environment interactions may not have the chance to reach equilibrium, leading to non-stationary, and non-Markovian statistical properties. These nonequilibrium features play a critical role in decoherence, [62,63] quantum speed limits, [64] and the geometric phase of quantum systems.…”

Section: Introductionmentioning

confidence: 99%

Nonequilibrium Effects on the Precision of Parameter Estimation

Cheng

2023

Annalen der Physik

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The impact of nonequilibrium environment effects on the accuracy of quantum parameter estimation is investigated, and it is found that these effects can significantly affect estimation accuracy. Using an individual estimation strategy reveals that the nonequilibrium effects consistently enhance accuracy, regardless of the coupling strength between the probe and its environment. In contrast, weak memory effects undermine estimation accuracy. When employing a multi‐parameter simultaneous estimation strategy, it is observed that the nonequilibrium effects consistently improve the advantages of simultaneous estimation, as analyzed by the ratio of total variances between the two estimation scenarios. However, the memory effects on these advantages depend on the coupling strength between the qubit and the environment. These findings suggest that appropriate parameters of a nonequilibrium environment can increase the quantum Fisher information (QFI), thereby enhancing the accuracy of quantum parameter estimation. These significant results are essential for improving parameter estimation accuracy in quantum systems interacting with nonequilibrium environments.

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Section: Introductionmentioning

confidence: 99%

Nonequilibrium Effects on the Precision of Parameter Estimation

Cheng

2023

Annalen der Physik

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Noise-to-energy conversion in a nanometer-scale dot observed with electron counting statistics

Chida

Fujiwara

Nishiguchi

2023

Applied Physics Letters

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We converted Gaussian-distributed voltage noise applied to an electron reservoir into the non-equilibrium free energy of a nanometer-scale dot connected to the reservoir via an energy barrier. Counting statistics of single-electron motion into and out of the dot through the energy barrier allows us to quantitatively analyze the energy transported into the dot as well as changes in the internal energy and effective temperature of the dot in this noise-induced non-equilibrium steady state (NESS). By analyzing the transition rates of electrons moving into and out of the dot, we confirmed that the rectification effect caused by the asymmetry with respect to the direction of electron motion is the origin of the increase in the internal energy of the dot. The information on energy transport in a nanometer-scale dot in the noise-induced NESS obtained in this study with electron counting statistics clarifies the relationship between the non-equilibrium dynamics of a nanodevice and noise applied to it. This study provides us with the means to evaluate device operation using noise as a resource.

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