Applications of entanglement at extreme distance scales

Entanglement, a unique feature of quantum mechanics in which two particles share correlations beyond what is possible classically, can be exploited for gains in sensing, communication, and computation. It can be used to connect quantum computers and sensors on a global scale and beyond, or for better sensing of the most sensitive phenomena. Here we will explore three such applications of entangled photons across a range of distance scales: First, a sensor which utilizes frequency entanglement to measure nanometer-scale displacements and vibrations with orders of magnitude fewer resources than traditional quantum approaches. We perform a theoretical study of noise in interferometry, comparing the effects of common noise sources on classical interference, degenerate two-photon interference, and frequency-entangled two-photon interference. We then construct a component-based noise model of such a frequency-entangled interferometer, which is used to predict performance of our experimental system based on real-world optics. Our experimental implementation of such an interferometer, utilizing frequency-entangled photon pairs at 810 nm and 1550 nm, is demonstrated to have two-photon interference visibility > 0.89, corresponding to a 88.6% saturation of the Quantum Cramér-Rao bound when used for metrology. Second, we present a theoretical model for noisy fiber- and space-based quantum networks, used to optimize network rates for inter/trans continental entanglement distribution. We study the effects of noise on swapping rates and finalized state quality, comparing different source technologies, detection methods, and link architectures. Finally, we discuss efforts to create a compact postselected entanglement source and integrated tomography system suitable for a space environment. Using a novel quantum-state tomography system consisting of only a single liquid crystal variable retarder per photon, we characterize the source, demonstrating entanglement fidelities in excess of 99%.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2024

Author dc:creator

• Johnson, Spencer James

Contributors dc:contributor

• Kwiat, Paul
• Lorenz, Virginia
• Chitambar, Eric
• Backlund, Mikael

• Quantum Information
• Quantum Optics
• Entanglement
• Quantum Sensing
• Quantum Networking

Statement dc:rights

• Copyright 2024 Spencer Johnson

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/125691

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F125691