Quantum applications of Raman-mediated photon-pair generation

Oolman, Kathleen

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https://hdl.handle.net/2142/127327 Copy

Description

Title

Quantum applications of Raman-mediated photon-pair generation

Author(s)

Oolman, Kathleen

Issue Date

2024-10-17

Director of Research (if dissertation) or Advisor (if thesis)

Lorenz, Virginia O

Doctoral Committee Chair(s)

Goldschmidt, Elizabeth A

Committee Member(s)

• Cohen, Offir
• DeMarco, Brian L
• Hoffmann, Axel F

Department of Study

Physics

Discipline

Physics

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• quantum optics
• photon pair
• Raman scattering
• integrated photonics
• silicon nitride
• photon purity

Abstract

Controllable generation of photon pairs is essential for the utilization of quantum pair states for quantum applications such as quantum communication, quantum cryptography, teleportation, and linear optics quantum computing. Raman scattering is one of the most fundamental light-matter interactions and can be used to generate photon pairs. Using the spontaneous Stokes Raman interaction, a photon from a strong pump laser pulse is annihilated, and a Stokes photon and Raman-mediated collective excitation are created. This excitation can then be read out deterministically as an anti-Stokes photon with the application of a second laser pulse within the excitation lifetime, creating a photon pair. The heralding capability of the Stokes photon and lifetime of the excitation makes this source quasi-deterministic, where the anti-Stokes photon can be created at a later time than the Stokes. This gives additional advantages and uses over traditional photon-pair sources using nonlinear interactions of light in a transparent medium, which generate the pair of photons simultaneously. In this thesis, we study the correlations of photon pairs generated via spontaneous Raman interactions and demonstrate how these interactions can be used for quantum applications. First, we develop a model to study the spectral correlations between the Raman generated Stokes and anti-Stokes photons. This model is used to calculate the spectral single-photon purity of the photons in a generic material system ignoring the effects of material dispersion. We calculate how various parameters effect the purity including pump spectral bandwidth, excitation linewidth, and time delay between pump pulses. We then introduced an experimental realization of a Raman-mediated photon-pair source in an integrated quantum photonic circuit platform. Interstitial N2 molecules inherently trapped in silicon nitride thin films during the deposition process possess a sharp Raman mission corresponding to the vibrational mode of the molecules, which can be used as a Raman-mediated photon-pair source. We present evidence of N2 defects in silicon nitride thin films and estimate the defect density and excitation lifetime. By patterning the films into waveguide structures, the photon-matter interaction is enhanced. We perform finite-element simulation of light propagation in our fabricated waveguides and use the results to examine effects from the waveguide on ultrafast optical pulses and phase-matching requirements for efficient photon-pair generation. We then present experimental progress towards detecting Stokes and anti-Stokes photon-pair generation from N2 defects in silicon nitride waveguides. We show results from degenerate and non-degenerate wavelength optical pump pulses. We discuss limitations of the experimental methods and study in detail the sources of noise arising from the silicon nitride waveguide, and conclude by discussing future extensions on the results presented here.

Graduation Semester

2024-12

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/127327

Copyright and License Information

Copyright 2024 Kathleen Oolman

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