Optical switching of radical pair conformation enhances magnetic sensitivity

Guerreschi, Gian Giacomo; Tiersch, Markus; Steiner, Ulrich; Briegel, Hans J.

doi:10.1016/j.cplett.2013.04.010

Cited by 10 publications

(62 citation statements)

References 37 publications

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“…In particular, given the discussion of the previous Section, how can one do better in a chemically realistic way? Towards addressing this question we will (i) take advantage of a very promising approach of optically switching the conformation of the radical-pair, recently proposed in [45], and (ii) include a realistic exchange interaction in the Hamiltonian, which changes (a) the initial spin state before the radicalpair commences its magnetometric state evolution, and (b) the effective measurement basis before it recombines.…”

Section: Quantum Reaction Controlmentioning

confidence: 99%

“…In summary, given the maximally anisotropic coupling that resulted from the optimization of Section V.C, the . 3. According to the proposal of [45], radical-pair reactions can be controlled by binding the two radicals to the two ends of a molecular switch, the conformation of which can be laser controlled. We here consider that apart from the Zeeman and hyperfine coupling term in the magnetic Hamiltonian, in the cis conformation there is also a finite exchange coupling, which the authors in [45] take to be infinite.…”

Section: Quantum Reaction Controlmentioning

confidence: 99%

“…We briefly reiterate the method of [45], since the added advantage we introduce by the exchange Hamiltonian is based on the same method of optically pulsing the conformation of the radical-pair. In particular, the authors in [45] suggest binding the donor and acceptor parts of the radical-pair to the two ends of a molecular switch, the conformation of which can be laser controlled. Schematically, this is shown in Fig.3.…”

Section: Quantum Reaction Controlmentioning

confidence: 99%

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Quantum-limited biochemical magnetometers designed using the Fisher information and quantum reaction control

Vitalis

Kominis

2017

Phys. Rev. A

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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. Here we address radical-pair reactions from the perspective of quantum metrology. Since the coherent spin motion of radical-pairs is effected 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 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. This work opens the application of well-advanced quantum metrology methods to biological systems. arXiv:1611.08902v1 [quant-ph]

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Section: Quantum Reaction Controlmentioning

confidence: 99%

Section: Quantum Reaction Controlmentioning

confidence: 99%

Section: Quantum Reaction Controlmentioning

confidence: 99%

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Quantum-limited biochemical magnetometers designed using the Fisher information and quantum reaction control

Vitalis

Kominis

2017

Phys. Rev. A

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“…Despite all of the theoretical arguments, the ultimate goal of studying the mechanisms of bird navigation is to learn from nature and to design highly effective devices that can mimic biological systems to detect weak magnetic fields, and to use the geomagnetic field to navigate. Previous literature has shown that the anisotropic hyperfine coupling plays a crucial role in the magnetic field sensitivity of the avian compass and has provided routes towards the design of biologically inspired magnetic compass sensors . Scientists have exploited many practical methods to realize a device based on the avian chemical compass.…”

Section: Chemical Compass In Birdsmentioning

confidence: 99%

“…Other studies have achieved to map nanomagnetic field using a radical pair reaction and found a method to improve the magnetic sensitivity of chemical magnetometers …”

Section: Chemical Compass In Birdsmentioning

confidence: 99%

The radical pair mechanism and the avian chemical compass: Quantum coherence and entanglement

Zhang

Berman

Kais

2015

Int J of Quantum Chemistry

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We review the spin radical pair mechanism which is a promising explanation of avian navigation. This mechanism is based on the dependence of product yields on (1) the hyperfine interaction involving electron spins and neighboring nuclear spins and (2) the intensity and orientation of the geomagnetic field. This review describes the general scheme of chemical reactions involving radical pairs generated from singlet and triplet precursors; the spin dynamics of the radical pairs; and the magnetic field dependence of product yields caused by the radical pair mechanism. The main part of the review includes a description of the chemical compass in birds. We review: the general properties of the avian compass; the basic scheme of the radical pair mechanism; the reaction kinetics in cryptochrome; quantum coherence and entanglement in the avian compass; and the effects of noise. We believe that the quantum avian compass can play an important role in avian navigation and can also provide the foundation for a new generation of sensitive and selective magnetic-sensing nanodevices. V C 2015 Wiley Periodicals, Inc. DOI: 10.1002/qua.24943 Radical Pair Mechanism IntroductionA radical is an atom, molecule or ion that has unpaired valence electrons. Radicals and radical pairs often play a very important role as intermediates in thermal, radiation, and photochemical reactions. [1] The presence of unpaired electron spins in these systems allows one to influence and control these reactions using interactions between external magnetic fields and electron spins. [2] However, until 1970, most scientists believed that ordinary magnetic fields had no significant effect on chemical or biochemical reactions, as the magnetic energy of typical molecules, under ordinary magnetic fields, is much smaller than the thermal energy at room temperature and is much smaller than the activation energies for those reactions. [1,2] This situation changed significantly in the 1970s after a series of experimental results were reported on magnetic field effects on chemical reactions. [3][4][5][6][7] Because of these experimental studies, a number of researchers have made an effort to theoretically explain the magnetic field effects on the chemical reactions. [8,9] Thanks to these and the subsequent efforts, we are now able to explain systematically magnetic field effects in terms of the radical pair mechanism. The radical pair mechanism was then successfully applied to explain the chemically induced nuclear polarization and electron polarization, which were shown to be based on the spin dynamics of radical pairs. [2] According to the radical pair mechanism, an external magnetic field affects chemical reactions by alternating the electron spin state of a weakly coupled radical pair, which is produced as an intermediate. The basic scheme of chemical reactions through the radical pairs is shown in Figure 1. Radical pairs are usually produced as short-lived intermediates through decomposition, electron transfer, or hydrogen transfer reactions from singlet or tr...

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