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Magnetic Field Effects in Quantum Biology: Beyond the Radical Pair Mechanism

量子生物学中的磁场效应：超越自由基对机制

基本信息

批准号：
1917982
负责人：
金额：
--
依托单位：
UNIVERSITY OF EXETER
依托单位国家：
英国
项目类别：
Studentship
财政年份：
2017
资助国家：
英国
起止时间：
2017 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-1917982
关键词：
Magnetic Field Effects Quantum Biology

项目摘要

In chemical reactions involving transient radical pairs, quantum effects induce a remarkable sensitivity to the intensity and/or orientation of external static magnetic fields as weak as the Earth's magnetic field. The governing principle of all these phenomena is the magnetic-field dependent interconversion between quantum-coherent and often entangled states of electronic spin pairs. Typically this process involves the formation of radical pairs by photo-induced electron transfer reactions, the coherent evolution of the resulting non-equilibrium electron spin states, and spin-selective recombination of the radicals. The effect has attracted widespread interest from the scientific community and general audiences owing to its putative relevance to animal magnetoreception, most notably in migratory birds, its link to possibly adverse effects of weak electromagnetic fields on human health, and the opportunity to increase the efficiency of photovoltaic devices.While magnetic field effects (MFEs) resulting from the radical pair mechanism (RPM) have been experimentally confirmed in model systems, they are often found to be small (1 % or less in the low-field region). In the framework of this project, we will theoretically investigate the exploitation of quantum phenomena to amplify MFEs or tailor their characteristics to particular applications. The candidate will focus on several mechanisms, most of which are utterly unexplored in this context: the effects of noise resulting from the stochastic modulation of the exchange and electron dipolar interaction by thermal motion; the accumulation of non-equilibrium nuclear polarizations over the course of several excitation cycles by a process known as three-spin mixing; and the amplification of MFEs by scavenging reactions with quenchers of non-zero spin multiplicity (chemical Zeno effect). This project will also address the mysterious observation that the magnetic compass of birds is disrupted by feeble radiofrequency magnetic fields. Currently this phenomenon can only be explained by assuming excessively long spin coherence times, which appear unphysical in noisy biological environments.The candidate will develop the theoretical models and numerical tools needed to provide a deep understanding of the underlying quantum physics and enable potential technological applications of the RPM in fields ranging from quantum biology (avian quantum compass) to material science (sensor applications).

在涉及瞬态自由基对的化学反应中，量子效应引起对与地球磁场一样弱的外部静磁场的强度和/或方向的显着敏感性。所有这些现象的主导原理是电子自旋对的量子相干态和经常纠缠态之间依赖于磁场的相互转换。典型地，该过程涉及通过光诱导电子转移反应形成自由基对、所得到的非平衡电子自旋态的相干演化以及自由基的自旋选择性重组。这种效应引起了科学界和普通观众的广泛兴趣，因为它被认为与动物的磁感受有关，特别是在候鸟中，它与弱电磁场对人类健康的可能不利影响有关，自由基对机制（RPM）产生的磁场效应（MFE）已经在模型系统中被实验证实，但是经常发现它们很小（在低场区域中为1%或更小）。在这个项目的框架内，我们将从理论上研究利用量子现象来放大MFE或根据特定应用定制其特性。候选人将侧重于几种机制，其中大多数是完全没有探索在这方面：噪声的影响所产生的随机调制的交换和电子偶极相互作用的热运动;积累的非平衡核极化在几个激发周期的过程中被称为三自旋混合;以及通过与非零自旋多重性的淬灭剂的清除反应（化学芝诺效应）放大MFE。该项目还将解决鸟类的磁罗盘被微弱的射频磁场干扰的神秘观察。目前这种现象只能通过假设过长的自旋相干时间来解释，这在嘈杂的生物环境中显得不符合物理学。候选人将开发所需的理论模型和数值工具，以提供对底层量子物理的深入理解，并使RPM在量子生物学（鸟类量子罗盘）到材料科学（传感器应用）等领域的潜在技术应用成为可能。