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Title: Quantum synchronisation of molecular motions in bio-inspired energy transfer systems
Author: Siwiak-Jaszek, Stefan
ISNI:       0000 0004 8499 948X
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2019
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Synchronisation is a collective phenomenon extensively studied in classical oscillators and, more recently, in quantum systems. The precise mechanisms of the phenomena in the latter regime remain unclear. In this thesis we investigate the fundamental mechanisms of quantum synchronisation through the theoretical analysis of a bio-inspired energy transfer system. Firstly, we numerically explore the oscillatory displacements of underdamped intramolecular vibrations in a vibronic dimer during energy transfer with Markovian decoherence and dissipation. We reveal that the vibrations synchronise in the timescale of the energy transfer process. We show that this synchronisation depends on the survival of specific vibronic coherences and explain how the competition between coherent and dissipative processes promotes synchronising coherences. We show that the time taken for synchronisation to emerge is positively correlated with fast coherent energy transport. Secondly, we investigate how the synchronisation dynamics of these vibrational motions contain signatures of quantum properties of the system. We reveal that a transient negatively synchronised period is a signature of excitonic coherence dominating the dynamics. We show that synchronisation with a constant phase difference occurs and is proportional to the detuning between the energies of the vibrations. We show that this may be a general feature of quantum synchronisation with detuning. Furthermore we show that this phase difference is correlated with a reduction in quantum correlations between synchronising subsystems. This result implies that our measure of synchronisation could be used as an indirect measure of a purely quantum property. Finally, we investigate synchronisation in the presence of non-Markovian environments and show that non-Markovian effects can be both beneficial and detrimental to synchronisation.
Supervisor: Olaya-Castro, A. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available