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Single Ion Detection of Cerium in Y2SiO5 Microcrystals

Kornienko, Vassily LU (2019) FYSM60 20182
Atomic Physics
Department of Physics
Abstract
Quantum computing with single instances of rare earth-ions doped into inorganic crystals shows great promise as a scalable design in the field of quantum information. A detectable and controllable single readout ion is necessary for the scheme proposed in Lund to work. Due to its short excited state lifetime and its cyclable 4f-5d transition, cerium has been deemed suitable for just this purpose. The approach taken in Lund for this single cerium detection is to use a homemade confocal microscopy setup. In previous work using this setup on bulk crystals, it has been assumed that the undetectability of single cerium is due to out of focus ions contributing to a noise floor that is higher than the fluorescence signal from a single one. Hence... (More)
Quantum computing with single instances of rare earth-ions doped into inorganic crystals shows great promise as a scalable design in the field of quantum information. A detectable and controllable single readout ion is necessary for the scheme proposed in Lund to work. Due to its short excited state lifetime and its cyclable 4f-5d transition, cerium has been deemed suitable for just this purpose. The approach taken in Lund for this single cerium detection is to use a homemade confocal microscopy setup. In previous work using this setup on bulk crystals, it has been assumed that the undetectability of single cerium is due to out of focus ions contributing to a noise floor that is higher than the fluorescence signal from a single one. Hence single ion detection is being attempted in microcrystals. This thesis outlines the process behind converting the confocal microscope into a microcrystal detection setup. Subsequently, Ce3+:Y2SiO5 microcrystal spectroscopy experiments were performed. The energy level structure of cerium is reported to be identical to bulk, with a slight shift in wavelength, and the inhomogenous linewidth has proven to be inconclusive, although it hints towards being much wider than in bulk. Quantifying the homogenous linewidth of the cerium ions using Zeeman hole burning techniques was impervious to our attempts. (Less)
Popular Abstract
Imagine an orchestra of professional musicians. They can read any set of notes that is presented to them and upon hearing the other musicians of the orchestra, will play their part in the correct volume and style. Furthermore, they all follow an identical 'clock' meaning that they all feel the same beat. They will even slow down or increase in speed all in sync. These musicians are also so skilled that even if there is a note missing in the score they are given, they will just know what to play, since it will follow naturally from the rest of the piece. Some more skillful musicians might even decide to add little details to the score that are not even written.

Now say that I, a non-musical person, somehow manage to sit down and write a... (More)
Imagine an orchestra of professional musicians. They can read any set of notes that is presented to them and upon hearing the other musicians of the orchestra, will play their part in the correct volume and style. Furthermore, they all follow an identical 'clock' meaning that they all feel the same beat. They will even slow down or increase in speed all in sync. These musicians are also so skilled that even if there is a note missing in the score they are given, they will just know what to play, since it will follow naturally from the rest of the piece. Some more skillful musicians might even decide to add little details to the score that are not even written.

Now say that I, a non-musical person, somehow manage to sit down and write a really complicated piece of music. I probably do this with the help of some mathematical formula and a computer. There is however a problem, one note is missing and there is no way, for the life of me, that I can figure out what that note is supposed to be. I decide to give it to the orchestra, let them play the score and try to listen for the missing note that one of the members will play. We have already secured that this member will play the missing note without a second thought, because it just naturally fits in with the rest of the piece.

However, when the orchestra starts playing and the time has come for the missing note to be played, the noise from all the other musicians will overshadow the sound coming from the musician who is supposed to play the missing note. Even after retrying hundreds of times, I cannot with certainty say what the missing note is, there is simply too much noise.

How can I find out what the missing note is? There are two possibilities:

+ I can ask the musician to play that note much louder than it is being played at the moment. Unfortunately upon hearing this loud note, the whole orchestra will collapse because the higher volume of the note will not flow with the rest of the score.
+ I could sit right next to the musician that is to play the missing note and listen very carefully. However, I will be a distraction to the musician and the rest of the orchestra so they will not even be able to start playing the piece.

A possibility that could work is to add another 'infiltrator' musician that can sit next to the person playing the missing note, remember it and then report it to me after the score has been played. That way, since the infiltrator is a musician, he/she will not gain attention from the others and also will remember the note that was played efficiently.

With this analogy in mind, imagine each musician is an atom that can be used as a quantum computer bit (qubit). With the assistance of laser pulses, each atom plays together in a quantum orchestra and we, the experimentalists, are looking for a certain unknown quantum state, or a note in the musician analogy. The infiltrator musician, or the link between us and the orchestra, will then correspond to a certain type of atom that interacts with the qubit atoms and us as the experimentalists. The link between the experimentalist and this infiltrator atom is where this thesis comes in, where I have worked on trying to detect a single atom in a crystal that contains billions. If this can be done, a very important milestone in quantum computing scheme pursued in Lund will be taken! (Less)
Please use this url to cite or link to this publication:
author
Kornienko, Vassily LU
supervisor
organization
course
FYSM60 20182
year
type
H2 - Master's Degree (Two Years)
subject
keywords
cerium, YSO, rare-earths, quantum computing, microcrystals
language
English
id
8967174
date added to LUP
2019-01-29 08:15:23
date last changed
2019-01-29 08:15:23
@misc{8967174,
  abstract     = {{Quantum computing with single instances of rare earth-ions doped into inorganic crystals shows great promise as a scalable design in the field of quantum information. A detectable and controllable single readout ion is necessary for the scheme proposed in Lund to work. Due to its short excited state lifetime and its cyclable 4f-5d transition, cerium has been deemed suitable for just this purpose. The approach taken in Lund for this single cerium detection is to use a homemade confocal microscopy setup. In previous work using this setup on bulk crystals, it has been assumed that the undetectability of single cerium is due to out of focus ions contributing to a noise floor that is higher than the fluorescence signal from a single one. Hence single ion detection is being attempted in microcrystals. This thesis outlines the process behind converting the confocal microscope into a microcrystal detection setup. Subsequently, Ce3+:Y2SiO5 microcrystal spectroscopy experiments were performed. The energy level structure of cerium is reported to be identical to bulk, with a slight shift in wavelength, and the inhomogenous linewidth has proven to be inconclusive, although it hints towards being much wider than in bulk. Quantifying the homogenous linewidth of the cerium ions using Zeeman hole burning techniques was impervious to our attempts.}},
  author       = {{Kornienko, Vassily}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Single Ion Detection of Cerium in Y2SiO5 Microcrystals}},
  year         = {{2019}},
}