| 1. |
- Fushitani, Mizuho, et al.
(författare)
-
Time-resolved photoelectron imaging of complex resonances in molecular nitrogen
- 2021
-
Ingår i: The Journal of chemical physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 154:14
-
Tidskriftsartikel (refereegranskat)abstract
- We have used the FERMI free-electron laser to perform time-resolved photoelectron imaging experiments on a complex group of resonances near 15.38 eV in the absorption spectrum of molecular nitrogen, N2, under jet-cooled conditions. The new data complement and extend the earlier work of Fushitani et al. [Opt. Express 27, 19702–19711 (2019)], who recorded time-resolved photoelectron spectra for this same group of resonances. Time-dependent oscillations are observed in both the photoelectron yields and the photoelectron angular distributions, providing insight into the interactions among the resonant intermediate states. In addition, for most states, we observe an exponential decay of the photoelectron yield that depends on the ionic final state. This observation can be rationalized by the different lifetimes for the intermediate states contributing to a particular ionization channel. Although there are nine resonances within the group, we show that by detecting individual photoelectron final states and their angular dependence, we can identify and differentiate quantum pathways within this complex system.
|
|
| 2. |
- Fushitani, Mizuho, et al.
(författare)
-
Wave packet dynamics and control in excited states of molecular nitrogen
- 2024
-
Ingår i: The Journal of chemical physics. - 0021-9606. ; 160:10
-
Tidskriftsartikel (refereegranskat)abstract
- Wave packet interferometry with vacuum ultraviolet light has been used to probe a complex region of the electronic spectrum of molecular nitrogen, N2. Wave packets of Rydberg and valence states were excited by using double pulses of vacuum ultraviolet (VUV), free-electron-laser (FEL) light. These wave packets were composed of contributions from multiple electronic states with a moderate principal quantum number (n ∼ 4-9) and a range of vibrational and rotational quantum numbers. The phase relationship of the two FEL pulses varied in time, but as demonstrated previously, a shot-by-shot analysis allows the spectra to be sorted according to the phase between the two pulses. The wave packets were probed by angle-resolved photoionization using an infrared pulse with a variable delay after the pair of excitation pulses. The photoelectron branching fractions and angular distributions display oscillations that depend on both the time delays and the relative phases of the VUV pulses. The combination of frequency, time delay, and phase selection provides significant control over the ionization process and ultimately improves the ability to analyze and assign complex molecular spectra.
|
|
| 3. |
- Nandi, Saikat, et al.
(författare)
-
Generation of entanglement using a short-wavelength seeded free-electron laser
- 2024
-
Ingår i: Science Advances. - 2375-2548. ; 10:16, s. 0668-0668
-
Tidskriftsartikel (refereegranskat)abstract
- Quantum entanglement between the degrees of freedom encountered in the classical world is challenging to observe due to the surrounding environment. To elucidate this issue, we investigate the entanglement generated over ultrafast timescales in a bipartite quantum system comprising two massive particles: a free-moving photoelectron, which expands to a mesoscopic length scale, and a light-dressed atomic ion, which represents a hybrid state of light and matter. Although the photoelectron spectra are measured classically, the entanglement allows us to reveal information about the dressed-state dynamics of the ion and the femtosecond extreme ultraviolet pulses delivered by a seeded free-electron laser. The observed generation of entanglement is interpreted using the time-dependent von Neumann entropy. Our results unveil the potential for using short-wavelength coherent light pulses from free-electron lasers to generate entangled photoelectron and ion systems for studying spooky action at a distance.
|
|
| 4. |
- Nandi, Saikat, et al.
(författare)
-
Generation of entanglement using a short-wavelength seeded free-electron laser
- 2024
-
Ingår i: SCIENCE ADVANCES. - 2375-2548. ; 10:16
-
Tidskriftsartikel (refereegranskat)abstract
- Quantum entanglement between the degrees of freedom encountered in the classical world is challenging to observe due to the surrounding environment. To elucidate this issue, we investigate the entanglement generated over ultrafast timescales in a bipartite quantum system comprising two massive particles: a free-moving photoelectron, which expands to a mesoscopic length scale, and a light-dressed atomic ion, which represents a hybrid state of light and matter. Although the photoelectron spectra are measured classically, the entanglement allows us to reveal information about the dressed-state dynamics of the ion and the femtosecond extreme ultraviolet pulses delivered by a seeded free-electron laser. The observed generation of entanglement is interpreted using the time-dependent von Neumann entropy. Our results unveil the potential for using short-wavelength coherent light pulses from free-electron lasers to generate entangled photoelectron and ion systems for studying spooky action at a distance.
|
|
| 5. |
- Nandi, Saikat, et al.
(författare)
-
Unraveling Rabi dynamics with a seeded FEL at XUV wavelength
- 2023
-
Ingår i: 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023. - 9798350345995
-
Konferensbidrag (refereegranskat)abstract
- Rabi oscillations, a prominent feature of coherent light-matter interaction arise when a two-level system interacts periodically with an external electromagnetic field [1]. Despite being a cornerstone in quantum physics, they are usually studied in the long-wavelength region, ranging from mid-infrared to visible. Here, we demonstrate that intense femtosecond extreme-ultraviolet (XUV) pulses from FERMI seeded free-electron laser [2] can drive Rabi oscillations between the two levels: 1s2 and 1s4p in helium.
|
|
| 6. |
- Patil, Indrajeet, et al.
(författare)
-
Neuroanatomical basis of concern-based altruism in virtual environment
- 2018
-
Ingår i: Neuropsychologia. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0028-3932 .- 1873-3514. ; 116, s. 34-43
-
Tidskriftsartikel (refereegranskat)abstract
- Costly altruism entails helping others at a cost to the self and prior work shows that empathic concern (EC) for the well-being of distressed and vulnerable individuals is one of the primary motivators of such behavior. However, extant work has investigated costly altruism with paradigms that did not feature self-relevant and severe costs for the altruist and have solely focused on neurofunctional, and not neuroanatomical, correlates. In the current study, we used a contextually-rich virtual reality environment to study costly altruism and found that individuals who risked their own lives in the virtual world to try to save someone in danger had enlarged right anterior insula and exhibited greater empathic concern than those who did not. These findings add to the growing literature showing the role of caring motivation in promoting altruism and prosociality and its neural correlates in the right anterior insula.
|
|
| 7. |
- Pedersoli, Emanuele, et al.
(författare)
-
Multipurpose modular experimental station for the DiProI beamline of Fermi@Elettra free electron laser
- 2011
-
Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 82:4, s. 043711-
-
Tidskriftsartikel (refereegranskat)abstract
- We present a compact modular apparatus with a flexible design that will be operated at the DiProI beamline of the Fermi@Elettra free electron laser (FEL) for performing static and time-resolved coherent diffraction imaging experiments, taking advantage of the full coherence and variable polarization of the short seeded FEL pulses. The apparatus has been assembled and the potential of the experimental setup is demonstrated by commissioning tests with coherent synchrotron radiation. This multipurpose experimental station will be open to general users after installation at the Fermi@Elettra free electron laser in 2011.
|
|
| 8. |
- Seidel, M., et al.
(författare)
-
Multi-pass Cell Based Nonlinear Pulse Compression of Yb : YAG Pump-Probe Lasers at FLASH
- 2023
-
Ingår i: X-Ray Free-Electron Lasers : Advances in Source Development and Instrumentation VI - Advances in Source Development and Instrumentation VI. - 1996-756X .- 0277-786X. - 9781510662827 ; 12581
-
Konferensbidrag (refereegranskat)abstract
- The majority of user experiments at the high repetition-rate free electron laser (FEL) facility FLASH are of pump-probe type, combining the extreme ultraviolet (XUV) or soft x-ray radiation from the FEL with ultrashort pulses generated by optical lasers. In this contribution, we demonstrate the advantages of using high-power Yb:YAG lasers with subsequent nonlinear pulse compression stages based on multi-pass cells (MPC). The approach enables the combination of hundreds of kHz to MHz repetition-rates, hundreds of watts of average powers and excellent intensity stabilities. We present the characteristics of the MPC-based pump-probe laser at the FLASH plane-grating beamlines. Furthermore, we report pulse compression to 8.2 fs pulse duration and the seeding of an optical parametric amplifier generating mid-IR radiation tunable from 1.4 µm to 16 µm.
|
|
