Advances in quantum information and thermodynamics with continuous variable systems

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XU, BUQING (2023) Advances in quantum information and thermodynamics with continuous variable systems. PhD thesis, University of Nottingham.

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Abstract

This thesis focuses on fundamental resources in quantum information theory with continuous variables and their applications to quantum optics and quantum thermodynamics. Our analysis mainly considers Gaussian states of continuous variable systems formed by two, three, or more modes, and adopts a variety of techniques to study their static and dynamical properties. Our original results include three main case studies: (i) quantifying genuine multipartite Bell nonlocality in permutationally invariant Gaussian states; (ii) characterising bipartite Einstein-Podolsky-Rosen (EPR) steering with non-Gaussian measurements; and (iii) benchmarking the reaction-coordinate mapping in non-equilibrium quantum harmonic chains.

In project (i), we investigate genuine multipartite nonlocality of multimode Gaussian states, as detected by the violation of Svetlichny inequality. We consider both displaced parity and pseudospin measurements and identify the largest violation of the inequality on permutationally invariant states. In the pseudospin case, we show that the maximum violation of Svetlichny inequality allowed by quantum mechanics can be approached for asymptotically large squeezing.

In project (ii) we study the detection of EPR steering (an asymmetric quantum correlation intermediate between entanglement and Bell nonlocality) in bipartite Gaussian states by pseudospin measurements. Our analysis reveals previously unexplored regimes where non-Gaussian measurements are more effective than Gaussian ones to witness steering of Gaussian states in the presence of local noise.

Finally, in project (iii) we analyze the validity of the reaction-coordinate mapping to characterise heat transport in an exactly solvable model: a two-node linear "quantum wire" connecting two baths at different temperatures. We find surprisingly that the stationary state of the original problem can be reproduced accurately by a weak-coupling treatment even in the regime of very strong residual dissipation.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: ADESSO, GERARDO
TUFARELLI, TOMMASO
Keywords: quantum information theory, quantum thermodynamics, continuous variable quantum systems
Subjects: Q Science > QC Physics > QC170 Atomic physics. Constitution and properties of matter
Q Science > QC Physics > QC20 Mathematical physics
Q Science > QC Physics > QC251 Heat
Faculties/Schools: UK Campuses > Faculty of Science > School of Mathematical Sciences
Item ID: 73547
Depositing User: Xu, Buqing
Date Deposited: 24 Nov 2025 09:03
Last Modified: 24 Nov 2025 09:03
URI: https://eprints.nottingham.ac.uk/id/eprint/73547

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