Control for quantum technologies at the nanoscale

Benjamin Rousseaux

Published Nov 8, 2016• 1 citation

Abstract

Controlling quantum emitters (atoms, molecules, quantum dots, etc.), light, and its interactionsis a key issue for implementing all-optical devices and information processing at thequantum level. This generally necessitates a strong coupling of emitters to photonic modes,as achieved by a high-Q cavity, for efficient manipulation of the atoms and field dynamicsthrough cavity quantum electrodynamics (cQED).The integration of the principles of quantum optics at the nanoscale in a plasmonic platformhas been envisioned, on the basis of a possible strong coupling between a quantum emitter andthe surface plasmon polaritons (SPPs) via their strong mode confinement. Recent progressshowed the possibility to reach such a strong coupling regime, allowing the development ofquantum plasmonics where a SPP mode takes the role of the cavity mode. However, its applicationappears notoriously limited in practical situations due to the intrinsic presence ofnumerous and lossy modes, which complicates the description and the interpretation of theinteraction, and introduces strong decoherence in the system, in particular for strong coupling.In this work, a detailed overview of quantum control applied to ion trapping, cQED, and plasmonics,is presented. The first part of the thesis is a study of adiabatic processes in trappedion systems and cQED:- We summarize quantum computation processes using quantum gates, and control usingadiabatic laser pulses with atomic systems.- We design arbitrary quantum gates with ions manipulated with laser pulses.- Models for cQED are derived and applied for the production of photon states leakingfrom a cavity.In the second part, we develop a formalism to describe the quantum dynamics of emitters closeto nanoscale structures, and numerics showing the strong coupling regime and the couplingof emitters via plasmon modes. More specifically:- We provide a general field quantization procedure for spherically layered systems.- Effective models using the field quantization are derived, and we show they are analogousto cQED models.- We describe the interaction of localized plasmons (LSPs) with quantum emitters.- The coupling/entanglement of emitters by adiabatic passage through lossy plasmonicmodes of a nanosphere is shown.

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