Double Attosecond Pulse Trains: Stability and Applications in Photoelectron Spectroscopy
(2026) FYSK04 20261Department of Physics
Atomic Physics
- Abstract
- In the 1980's the process of high-order harmonic generation (HHG) was discovered. It was later shown that HHG produces attosecond pulse trains (APTs), with 1 as = 10^(-18) s, using a photoelectron interferometric technique called reconstruction of attosecond beating by interference of two-photon transitions (RABBIT). RABBIT uses a combination of an APT, which ionizes a gas, and an infrared (IR) pulse to find phase information about the APT and the resulting photoelectrons. Theoretically, using a double APT instead of one, which introduces additional interference, enabling access to finer phase variations and may allow decoherence effects to be studied.
In this thesis, a double RABBIT (DRABBIT) technique utilizing pairs of APTs is... (More) - In the 1980's the process of high-order harmonic generation (HHG) was discovered. It was later shown that HHG produces attosecond pulse trains (APTs), with 1 as = 10^(-18) s, using a photoelectron interferometric technique called reconstruction of attosecond beating by interference of two-photon transitions (RABBIT). RABBIT uses a combination of an APT, which ionizes a gas, and an infrared (IR) pulse to find phase information about the APT and the resulting photoelectrons. Theoretically, using a double APT instead of one, which introduces additional interference, enabling access to finer phase variations and may allow decoherence effects to be studied.
In this thesis, a double RABBIT (DRABBIT) technique utilizing pairs of APTs is developed and tested. First, a beamsplitter-based interferometer is built and aligned, and used to generate IR pulse pairs with a controllable time delay. A method for extracting the pulse delay from recorded IR spectra is outlined. The delay stability is tested over the short- and long-term and it is found that the delay remains stable within a few hundred attoseconds over half an hour. The interferometer is then implemented into the RABBIT setup to generate pairs of APTs, and a DRABBIT scan is performed in helium. Unexpected harmonic peak broadening is observed when a pulse pair is used for HHG, implying more complex mechanisms in the generation process. The DRABBIT data show phase variations inside individual harmonics, which are not accessible in the normal RABBIT scheme. These results demonstrate that DRABBIT is a viable technique for accessing additional phase information. (Less) - Popular Abstract
- But who measures the attosecond ruler?
In 1987, Anne L'Hullier and coworkers made an extraordinary discovery. When a gas like argon is shot with a strong laser, the electrons in the gas will perform a microscopic dance that causes ultraviolet light to be emitted. The light consists of a train of pulses, and what is remarkable is that each pulse is only a few hundred attoseconds long. How short is an attosecond then? Well, it is a billionth of a billionth of a second. To put that into perspective, a second is to an attosecond what the age of the universe is to a second. This is actually the natural timescale of electron motion inside atoms. The attosecond pulse train essentially works like a ruler in time, with attosecond sized tick... (More) - But who measures the attosecond ruler?
In 1987, Anne L'Hullier and coworkers made an extraordinary discovery. When a gas like argon is shot with a strong laser, the electrons in the gas will perform a microscopic dance that causes ultraviolet light to be emitted. The light consists of a train of pulses, and what is remarkable is that each pulse is only a few hundred attoseconds long. How short is an attosecond then? Well, it is a billionth of a billionth of a second. To put that into perspective, a second is to an attosecond what the age of the universe is to a second. This is actually the natural timescale of electron motion inside atoms. The attosecond pulse train essentially works like a ruler in time, with attosecond sized tick marks, which allows scientists to measure the movement of electrons! But for such precise measurements, it is important to know exactly how the ruler itself looks like. We can take a closer look at our pulse train by shooting another gas with it. The ultraviolet light carries enough energy to eject electrons from the atoms. These electrons fly away with different kinetic energies, which can be measured and plotted as a landscape of peaks and valleys. Hidden within this mountain range is information about the structure of the pulse train, so by mapping out the landscape, we can reconstruct the shape of our attosecond ruler. With this method, we can get the rough overall shape, but what if you want more detail? That is where my project comes in. We take a copy of the attosecond pulse train and overlap it with the original, before sending it into a gas. This also produces a landscape, but one with more detail, which can be used to more accurately reconstruct the attosecond ruler. The hope is that this technique can later be used to study electron motion, but in more complex systems such as molecules, and to investigate decoherence, which describes the transition between microscopic quantum behavior and macroscopic everyday behavior. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/student-papers/record/9234246
- author
- Zigmantas, Linas LU
- supervisor
-
- David Busto LU
- Gustav Arvidsson LU
- organization
- course
- FYSK04 20261
- year
- 2026
- type
- M2 - Bachelor Degree
- subject
- keywords
- Attosecond physics, HHG, RABBIT, photoelectron spectroscopy
- language
- English
- id
- 9234246
- date added to LUP
- 2026-06-28 11:21:34
- date last changed
- 2026-06-28 11:21:34
@misc{9234246,
abstract = {{In the 1980's the process of high-order harmonic generation (HHG) was discovered. It was later shown that HHG produces attosecond pulse trains (APTs), with 1 as = 10^(-18) s, using a photoelectron interferometric technique called reconstruction of attosecond beating by interference of two-photon transitions (RABBIT). RABBIT uses a combination of an APT, which ionizes a gas, and an infrared (IR) pulse to find phase information about the APT and the resulting photoelectrons. Theoretically, using a double APT instead of one, which introduces additional interference, enabling access to finer phase variations and may allow decoherence effects to be studied.
In this thesis, a double RABBIT (DRABBIT) technique utilizing pairs of APTs is developed and tested. First, a beamsplitter-based interferometer is built and aligned, and used to generate IR pulse pairs with a controllable time delay. A method for extracting the pulse delay from recorded IR spectra is outlined. The delay stability is tested over the short- and long-term and it is found that the delay remains stable within a few hundred attoseconds over half an hour. The interferometer is then implemented into the RABBIT setup to generate pairs of APTs, and a DRABBIT scan is performed in helium. Unexpected harmonic peak broadening is observed when a pulse pair is used for HHG, implying more complex mechanisms in the generation process. The DRABBIT data show phase variations inside individual harmonics, which are not accessible in the normal RABBIT scheme. These results demonstrate that DRABBIT is a viable technique for accessing additional phase information.}},
author = {{Zigmantas, Linas}},
language = {{eng}},
note = {{Student Paper}},
title = {{Double Attosecond Pulse Trains: Stability and Applications in Photoelectron Spectroscopy}},
year = {{2026}},
}