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Main Authors: Chowdhury, Farhan T., Denton, Matt C. J., Bonser, Daniel C., Kattnig, Daniel R.
Format: Preprint
Published: 2023
Subjects:
Online Access:https://arxiv.org/abs/2306.08613
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author Chowdhury, Farhan T.
Denton, Matt C. J.
Bonser, Daniel C.
Kattnig, Daniel R.
author_facet Chowdhury, Farhan T.
Denton, Matt C. J.
Bonser, Daniel C.
Kattnig, Daniel R.
contents We realize arbitrary waveform-based control of spin-selective recombination reactions of radical pairs in the low magnetic field regime. To this end, we extend the Gradient Ascent Pulse Engineering (GRAPE) paradigm to allow for optimizing reaction yields. This overcomes drawbacks of previously suggested time-local optimization approaches for the reaction control of radical pairs, which were limited to high biasing fields. We demonstrate how efficient time-global optimization of the recombination yields can be realized by gradient based methods augmented by time-blocking, sparse sampling of the yield, and evaluation of the central single time-step propagators and their Fréchet derivatives using iterated Trotter-Suzuki splittings. Results are shown for both a toy model, previously used to demonstrate coherent control of radical pair reactions in the simpler high-field scenario, and furthermore for a realistic exciplex-forming donor-acceptor system comprising 16 nuclear spins. This raises prospects for the spin-control of actual radical pair systems in ambient magnetic fields, by suppressing or boosting radical reaction yields using purpose-specific radio-frequency waveforms, paving the way for reaction-yield-dependent quantum magnetometry and potentially applications of quantum control to biochemical radical pair reactions. We demonstrate the latter aspect for two radical pairs implicated in quantum biology.
format Preprint
id arxiv_https___arxiv_org_abs_2306_08613
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Quantum Control of Radical Pair Dynamics beyond Time-Local Optimization
Chowdhury, Farhan T.
Denton, Matt C. J.
Bonser, Daniel C.
Kattnig, Daniel R.
Chemical Physics
Computational Physics
Quantum Physics
We realize arbitrary waveform-based control of spin-selective recombination reactions of radical pairs in the low magnetic field regime. To this end, we extend the Gradient Ascent Pulse Engineering (GRAPE) paradigm to allow for optimizing reaction yields. This overcomes drawbacks of previously suggested time-local optimization approaches for the reaction control of radical pairs, which were limited to high biasing fields. We demonstrate how efficient time-global optimization of the recombination yields can be realized by gradient based methods augmented by time-blocking, sparse sampling of the yield, and evaluation of the central single time-step propagators and their Fréchet derivatives using iterated Trotter-Suzuki splittings. Results are shown for both a toy model, previously used to demonstrate coherent control of radical pair reactions in the simpler high-field scenario, and furthermore for a realistic exciplex-forming donor-acceptor system comprising 16 nuclear spins. This raises prospects for the spin-control of actual radical pair systems in ambient magnetic fields, by suppressing or boosting radical reaction yields using purpose-specific radio-frequency waveforms, paving the way for reaction-yield-dependent quantum magnetometry and potentially applications of quantum control to biochemical radical pair reactions. We demonstrate the latter aspect for two radical pairs implicated in quantum biology.
title Quantum Control of Radical Pair Dynamics beyond Time-Local Optimization
topic Chemical Physics
Computational Physics
Quantum Physics
url https://arxiv.org/abs/2306.08613