Which-path problem for one and two particles with two degrees of freedom and a relation between transverse spatial structure and group velocity of light

Ferenczi, Gergely (2016) Which-path problem for one and two particles with two degrees of freedom and a relation between transverse spatial structure and group velocity of light. PhD thesis, University of Glasgow.

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Printed Thesis Information: https://eleanor.lib.gla.ac.uk/record=b3176704


Quantum mechanics, optics and indeed any wave theory exhibits the phenomenon of interference. In this thesis we present two problems investigating interference due to indistinguishable alternatives and a mostly unrelated investigation into the free space propagation speed of light pulses in particular spatial modes.
In chapter 1 we introduce the basic properties of the electromagnetic field needed for the subsequent chapters. In chapter 2 we review the properties of interference using the beam splitter and the Mach-Zehnder interferometer.
In particular we review what happens when one of the paths of the interferometer is marked in some way so that the particle having traversed it contains information as to which path it went down (to be followed up in chapter 3) and we review Hong-Ou-Mandel interference at a beam splitter (to be followed up in chapter 5).
In chapter 3 we present the first of the interference problems. This consists of a nested Mach-Zehnder interferometer in which each of the free space propagation segments are weakly marked by mirrors vibrating at different
frequencies [1]. The original experiment drew the conclusions that the photons followed disconnected paths. We partition the description of the light in the interferometer according to the number of paths it contains which-way information about and reinterpret the results reported in [1] in terms of the interference of paths spatially connected from source to detector.
In chapter 4 we briefly review optical angular momentum, entanglement and spontaneous parametric down conversion. These concepts feed into chapter 5 in which we present the second of the interference problems namely
Hong-Ou-Mandel interference with particles possessing two degrees of freedom. We analyse the problem in terms of exchange symmetry for both boson and fermion pairs and show that the particle statistics at a beam splitter
can be controlled for suitably chosen states. We propose an experimental test of these ideas using orbital angular momentum entangled photons.
In chapter 6 we look at the effect that the transverse spatial structure of the mode that a pulse of light is excited in has on its group velocity. We show that the resulting group velocity is slower than the speed of light in vacuum
for plane waves and that this reduction in the group velocity is related to the spread in the wave vectors required to create the transverse spatial structure. We present experimental results of the measurement of this slowing
down using Hong-Ou-Mandel interference.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Subjects: Q Science > QC Physics
Colleges/Schools: College of Science and Engineering > School of Physics and Astronomy
Funder's Name: Engineering & Physical Sciences Research Council (EPSRC)
Supervisor's Name: Barnett, Professor Stephen M.
Date of Award: 2016
Depositing User: Mr Gergely P Ferenczi
Unique ID: glathesis:2016-7475
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 13 Jul 2016 07:44
Last Modified: 02 Nov 2016 11:41
URI: https://theses.gla.ac.uk/id/eprint/7475

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