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Light-Matter Interaction and Quantum Computing in Rare-Earth-Ion-Doped Crystals

Kinos, Adam LU (2018)
Abstract
In this thesis, crystals of yttrium orthosilicate (Y2SiO5) that are randomly doped with another rare-earth element, such as praseodymium (Pr), europium (Eu), or cerium (Ce), are investigated with lasers locked to ultra-stable cavities using the Pound-Drever-Hall locking technique.

Many of these rare-earth elements have long-lived 4f-4f transitions, hundreds of microseconds to a few milliseconds, with even longer ground hyperfine lifetimes of up to several days. The coherence properties are, to the best of the author's knowledge, the longest achieved for any material, currently with a record of six hours for the nuclear spin states of Eu3+:Y2SiO5 measured at cryogenic... (More)
In this thesis, crystals of yttrium orthosilicate (Y2SiO5) that are randomly doped with another rare-earth element, such as praseodymium (Pr), europium (Eu), or cerium (Ce), are investigated with lasers locked to ultra-stable cavities using the Pound-Drever-Hall locking technique.

Many of these rare-earth elements have long-lived 4f-4f transitions, hundreds of microseconds to a few milliseconds, with even longer ground hyperfine lifetimes of up to several days. The coherence properties are, to the best of the author's knowledge, the longest achieved for any material, currently with a record of six hours for the nuclear spin states of Eu3+:Y2SiO5 measured at cryogenic temperatures. Furthermore, due to natural trapping and differences in the local environments, each dopant ion experiences a slightly different crystal field, and thus an inhomogeneity in the 4f-4f transition exists between all ions in a crystal. Since the homogeneous linewidth is in the order of kHz or below, whereas the inhomogeneous profile can be several GHz wide, these materials have dense storing capabilities.

This thesis explores how light interacts with such rare-earth-ion-doped crystals; how the absorption and light polarization varies during propagation; how spectral features in the inhomogeneous absorption profile can be tailored to create narrowband spectral filters; how the speed of light is slowed down significantly in such narrow transmission windows; and how that can be used to either frequency shift incoming light, control its group velocity, or temporally compress pulses.

It also uses rare-earth-ions to research quantum computing, the field of using quantum mechanical effects such as superpositions and entanglements to outperform classical computers on certain specific problems. This is done by examining how two-color pulses can be used to rapidly induce coherence from an initially mixed state; how qubit-qubit interactions can be performed experimentally using ensemble qubits, which opens the door to two-qubit experiments such as the CNOT-gate and entanglements; how a scalable quantum computer might be constructed using a single ion qubit approach with a dedicated readout ion and buffer ion(s) to improve readout fidelity; and how cerium is investigated as a candidate for such a dedicated readout ion.
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author
supervisor
opponent
  • Dr Thiel, Charles W., Montana State University, Bozeman, MT, USA
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Rare-Earth-Ion-Doped Crystals, Quantum Computing, Light-Matter Interaction, Fysicumarkivet A:2018:Kinos
pages
219 pages
publisher
Atomic Physics, Department of Physics, Lund University
defense location
Lecture hall Rydbergsalen, Fysicum, Professorsgatan 1, Lund University, Faculty of Engineering LTH.
defense date
2018-03-02 09:15
ISBN
978-91-7753-544-7
978-91-7753-543-0
language
English
LU publication?
yes
id
07cdb1db-8959-4462-9f1c-984c55f4a61b
date added to LUP
2018-02-05 13:58:07
date last changed
2018-05-29 12:15:54
@phdthesis{07cdb1db-8959-4462-9f1c-984c55f4a61b,
  abstract     = {In this thesis, crystals of yttrium orthosilicate (Y<sub>2</sub>SiO<sub>5</sub>) that are randomly doped with another rare-earth element, such as praseodymium (Pr), europium (Eu), or cerium (Ce), are investigated with lasers locked to ultra-stable cavities using the Pound-Drever-Hall locking technique. <br/><br/>Many of these rare-earth elements have long-lived 4f-4f transitions, hundreds of microseconds to a few milliseconds, with even longer ground hyperfine lifetimes of up to several days. The coherence properties are, to the best of the author's knowledge, the longest achieved for any material, currently with a record of six hours for the nuclear spin states of Eu<sup>3+</sup>:Y<sub>2</sub>SiO<sub>5</sub> measured at cryogenic temperatures. Furthermore, due to natural trapping and differences in the local environments, each dopant ion experiences a slightly different crystal field, and thus an inhomogeneity in the 4f-4f transition exists between all ions in a crystal. Since the homogeneous linewidth is in the order of kHz or below, whereas the inhomogeneous profile can be several GHz wide, these materials have dense storing capabilities.<br/><br/>This thesis explores how light interacts with such rare-earth-ion-doped crystals; how the absorption and light polarization varies during propagation; how spectral features in the inhomogeneous absorption profile can be tailored to create narrowband spectral filters; how the speed of light is slowed down significantly in such narrow transmission windows; and how that can be used to either frequency shift incoming light, control its group velocity, or temporally compress pulses. <br/><br/>It also uses rare-earth-ions to research quantum computing, the field of using quantum mechanical effects such as superpositions and entanglements to outperform classical computers on certain specific problems. This is done by examining how two-color pulses can be used to rapidly induce coherence from an initially mixed state; how qubit-qubit interactions can be performed experimentally using ensemble qubits, which opens the door to two-qubit experiments such as the CNOT-gate and entanglements; how a scalable quantum computer might be constructed using a single ion qubit approach with a dedicated readout ion and buffer ion(s) to improve readout fidelity; and how cerium is investigated as a candidate for such a dedicated readout ion. <br/>},
  author       = {Kinos, Adam},
  isbn         = {978-91-7753-544-7},
  keyword      = {Rare-Earth-Ion-Doped Crystals,Quantum Computing,Light-Matter Interaction,Fysicumarkivet A:2018:Kinos},
  language     = {eng},
  month        = {02},
  pages        = {219},
  publisher    = {Atomic Physics, Department of Physics, Lund University},
  school       = {Lund University},
  title        = {Light-Matter Interaction and Quantum Computing in Rare-Earth-Ion-Doped Crystals},
  year         = {2018},
}