Synchronisation in open quantum systems

Davis-Tilley, Claire (2018) Synchronisation in open quantum systems. PhD thesis, University of Nottingham.

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Synchronisation has been explored extensively for classical systems from the mid-1600s, and is a phenomenon widely understood in many diverse systems. In the age of technology miniaturisation, there are great incentives to develop an understanding of quantum synchronisation, where quantum fluctuations become the dominant source of noise and non-classical features become important. This thesis considers different types of synchronisation in systems that can display highly non-linear, quantum behaviours.

Phase synchronisation for a micromaser coupled to an external drive is initially considered, and it is found that for low photon numbers a semiclassical approximation underestimates phase synchronisation, but a perturbation theory can be accurate for sufficiently weak coupling in either a quantum or semiclassical regime. When a small detuning between the drive and micromaser is introduced, frequency entrainment is also found to exist.

Then two micromasers are coupled with each other, in two different configurations, and synchronisation through a relative phase preference is found for each. A semiclassical approximation once again underestimates the phase synchronisation. Entanglement and mutual information are found to behave differently to the relative phase preference depending on each system's parameters.

Finally, a mean-field theory is considered for many coupled van der Pol oscillators and micromasers respectively. As the coupling between the oscillators is increased, a critical point is reached and the systems undergo a transition to a phase synchronised state. This bistability appears via a saddle-node bifurcation, and in addition to examining a variety of properties before and after the transition the critical scaling behaviour was investigated close to the transition.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Armour, Andrew
Subjects: Q Science > Q Science (General)
Q Science > QC Physics > QC170 Atomic physics. Constitution and properties of matter
Faculties/Schools: UK Campuses > Faculty of Science > School of Physics and Astronomy
Item ID: 49492
Depositing User: Davis-Tilley, Claire
Date Deposited: 19 Jul 2018 04:40
Last Modified: 13 Aug 2018 14:30

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