E-Locus - Institutional Repository of the University of Crete

Home Collections School/Department School of Sciences and Engineering Department of Physics Doctoral theses

Doctoral theses

Current Record: 49 of 167

[Add to Basket]

Identifier

000409409

Title

Quantum metrology in biochemical magnetometers

Alternative Title

Κβαντική μετρολογία σε βιοχημικά μαγνητόμετρα

Author

Βιτάλης, Κυριάκος Μ.

Thesis advisor

Κομίνης, Ιωάννης

Thesis advisor

Ζώτος, Ξενοφών
Χαραλαμπίδης, Δημήτριος

Abstract

Radical-ion pairs and their reactions have triggered the study of quantum effects in biological systems. This is because they exhibit a number of effects best understood within quantum information science, and at the same time are central in understanding the avian magnetic compass and the spin transport dynamics in photosynthetic reaction centers. These pairs of biomolecular ions are recently shown to be biological open quantum systems. We show that the coupling of the radical-pair spin degrees of freedom to its decohering vibrational reservoir leads to a phononic Lamb shift of the radical-pair magnetic energy levels. The Lamb shift Hamiltonian is diagonal in the singlet-triplet basis, and results in a singlet-triplet energy splitting physically indistinguishable from an exchange interaction. This could have significant implications for understanding the energy level structure and the dynamics of photosynthetic reaction centers, which are intimately connected with the remarkable efficiency of photosynthesis [Eur. Phys. J. Plus 129, 187 (2014)]. Moreover, we address radical-pair reactions from the perspective of quantum metrology and parameter estimation. Since the coherent spin-motion of radical pairs is affected by an external magnetic field, these spin-dependent reactions essentially realize a biochemical magnetometer. Using the quantum Fisher information, we find the fundamental quantum limits to the magnetic sensitivity of radical-pair magnetometers. We then explore how well the usual measurement scheme considered in radical-pair reactions, the measurement of reaction yields, approaches the fundamental limits. In doing so, we find the optimal hyperfine interaction Hamiltonian that leads to the best magnetic sensitivity as obtained from reaction yields. This is still an order of magnitude smaller than the absolute quantum limit. Finally, we demonstrate that with a realistic quantum reaction control reminding one of Ramsey interferometry, here presented as a quantum circuit involving the spin-exchange interaction and a recently proposed molecular switch, we can approach the fundamental quantum limit within a factor of 2. Hence, this work opens the application of well-advanced quantum metrology methods to biological systems [Phys. Rev. A 95, 032129 (2017)].

Language

English

Subject

Lamb shift

Quantum Fisher information

Quantum biology

Radical pair

Ζεύγος ιοντικών ριζών

Κβαντική βιολογία

Κβαντική πληροφορία Fisher

Μετατόπιση Lamb

Issue date