MEASURING THE QUANTUM STATE OF PHOTOELECTRONS
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OVERVIEW:
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This data storage contains the Continuous variable quantum state tomography protocol for photoelectrons (KRAKEN) scans for helium and argon. KRAKEN is a protocol allowing for tomography of photoelectrons by reconstructing their density matrix. The repository also houses the photoelectron spectrometer response function data and the probe IR spectra.

- The file formats in the data set are only .csv
- In total there are 38 files in the dataset
- The dataset has been used in the article “Measuring the quantum state of photoelectrons” (https://arxiv.org/pdf/2309.13945) which gives a detailed description of how the data has been analyzed.

NAMING CONVENTION:
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KRAKEN files are named following the pattern `X_TOF_770_Y`. 
- `X`: Represents the type of gas, where `Ar` stands for argon and `He` stands for helium.
- `TOF`: Indicates that it is a KRAKEN scan in time of flight.
- `770`: Represents the wavelength of the first probe in nanometers.
- `Y`: Denotes the wavelength of the second probe spectral component, which varies from 790 to 840 in increments of 10.

For example, a file named `Ar_TOF_770_810` would refer to an argon KRAKEN scan with a first probe wavelength of 770 nm and a second probe wavelength of 810 nm.

DIRECTORY STRUCTURE:
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Ar
|-- Ar KRAKEN Scans/
|-- Probe Spectra/

He
|-- He KRAKEN Scans/
|-- Probe Spectra/

Spectrometer Response Function

DETAILED BREAKDOWN:
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Ar
|-- Ar KRAKEN Scans
	-X_TOF_770_Y.csv: KRAKEN Scans. Each element in the matrices contains the photoelectron counts given a specific time of flight and pump-probe delay for argon.
	-X_TOF_770_closed.csv: KRAKEN scan with no probe IR
	-X_TOF_770_open.csv: KRAKEN scan with probe IR at 770 nm wavelength
	-PumpProbeDelay.csv: Pump-probe Delay Vector (in femtoseconds). Delay between XUV pump and bichromatic infrared probe for argon.
	-TOF.csv: Time of Flight Vector (in nanoseconds). Represents the duration taken by photoelectrons to reach the detector post ionization.

|-- Probe Spectra
	-Spectra_770.csv: The file, Spectra_700.csv, has half the intensity compared to the other spectra. This is due to the chopper blocking half of the IR laser pulses.
	-Spectra_700_Y.csv: The probe spectra files, housed under the Probe Spectra directory for both helium and argon, represent data recorded with an IR spectrometer. These spectra are measured in Intensity (with units being arbitrary) and have been temporally integrated over the corresponding KRAKEN scan.
	-Wavelenghts.csv: The `Wavelengths.csv` file provides the spectral wavelengths in nanometers (nm) for which the intensity values of the spectra are recorded.

He
|-- He KRAKEN Scans
	-X_TOF_770_Y.csv: KRAKEN Scans. Each element in the matrices contains the photoelectron counts given a specific time of flight and pump-probe delay for helium.
	-X_TOF_770_closed.csv: KRAKEN scan with no probe IR
	-X_TOF_770_open.csv: KRAKEN scan with probe IR at 770 nm wavelength
	-PumpProbeDelay.csv: Pump-probe Delay Vector (in femtoseconds). Delay between XUV pump and bichromatic infrared probe for helium.
	-TOF.csv: Time of Flight Vector (in nanoseconds). Represents the duration taken by photoelectrons to reach the detector post ionization.

|-- Probe Spectra
	-Spectra_770.csv: The file, Spectra_700.csv, has half the intensity compared to the other spectra. This is due to the chopper blocking half of the IR laser pulses.
	-Spectra_700_Y.csv: The probe spectra files, housed under the Probe Spectra directory for both helium and argon, represent data recorded with an IR spectrometer. These spectra are measured in Intensity (with units being arbitrary) and have been temporally integrated over the corresponding KRAKEN scan.
	-Wavelenghts.csv: The `Wavelengths.csv` file provides the spectral wavelengths in nanometers (nm) for which the intensity values of the spectra are recorded.

Spectrometer Response Function
	-He_TOF_Response.csv: Response Function. Photoelectron counts for below threshold ionization in helium. The 3p Rydberg state in helium is populated by the XUV and following absorption of a narrowband (10 nm) IR probe, a photoelectron is ejected. This data images the photoelectron spectrometer's response.
	-TOF.csv: Time of Flight Vector (in nanoseconds). Represents the duration taken by photoelectrons to reach the detector post ionization.

700 nm SCAN INFORMATION:
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For the 700 nm scans, a chopper was employed where the infrared (IR) probe was alternately blocked. Consequently, for each 700 nm scan, two KRAKEN scans are available: one where the chopper is open, allowing the IR probe, and one where it's closed, blocking the probe.

ADDITIONAL INFORMATION:
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From the time-of-flight data, the scans can be re-binned to represent the photoelectron kinetic energy. To calculate the electron kinetic energy based on the time of flight the following information is needed:
	- The length of the flight tube is 2 m.
	- A retarding voltage was applied at the entrance of the flight tube. In the case of helium of 3.7 V and in 	the case of argon 12.4 V.

In kinetic energy, consecutive photoelectron peaks should be equally spaced by approximately 1.55 eV.

CONTACT:
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For further inquiries, please contact David Busto, david.busto@fysik.lth.se
