Maximizing hole coherence in ultrafast photoionization of argon with an optimization by sequential parametrization update

Goetz, R. Esteban; Merkel, Maximilian; Karamatskou, Antonia; Santra, Robin; Koch, Christiane P.

doi:10.1103/physreva.94.023420

Cited by 17 publications

(20 citation statements)

References 45 publications

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“…In order for coherence to build up, the excited electrons of the 1p1h states need to be in the same oneparticle state. This can be achieved via multiphoton processes, as has been demonstrated by Goetz et al [74,75]. For the large electric-field strengths considered here, it is possible that electrons with the same angular momentum are excited from both the 3s and the 3p 0 orbital.…”

Section: A Results For One Pump Pulsementioning

confidence: 55%

Attosecond x-ray scattering from a particle-hole wave packet

2017

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We investigate the imaging of electron wave-packet dynamics by measuring the pattern of inelastically scattered photons. For this purpose, we develop a theory of time-resolved Compton scattering. We demonstrate that, by using a sufficiently short x-ray pulse, the scattering cross section directly reflects the instantaneous momentum density of the electron. Therefore, we propose time-resolved Compton scattering as a tool to image electron wave-packet dynamics in momentum space. To illustrate this, we simulate electron wave packets in argon by using the time-dependent configuration-interaction singles method. Specifically, we consider coherent particle-hole wave packets, where the hole is in either the 3p or the 3s shell, and the particle (the excited electron) is either in a Rydberg state or in the continuum. Our calculations confirm that the dynamics of electron wave packets can indeed be imaged by measuring the doubly differential Compton scattering cross section. When the x-ray detector has no energy resolution at all, the contribution of Compton scattering to the differential scattering cross section becomes stationary. In that case, the motion of the particle and the hole can no longer be inferred from the scattering pattern.

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Section: A Results For One Pump Pulsementioning

confidence: 55%

Attosecond x-ray scattering from a particle-hole wave packet

2017

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“…For neglible heating, the required field strength per beam can be reduced by using three instead of four beams to drive the two sideband transitions (blue curve in figure 8). This finding illustrates that parameter optimization is prone to trapping in local optima, in particular for a larger number of optimization parameters [46]. We attribute the improvement to the fact that omission of one beam reduces the inadvertent scattering.…”

Section: Comparison To the Original Schemementioning

confidence: 87%

Quantum optimal control of the dissipative production of a maximally entangled state

et al. 2018

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Entanglement generation can be robust against certain types of noise in approaches that deliberately incorporate dissipation into the system dynamics. The presence of additional dissipation channels may, however, limit fidelity and speed of the process. Here we show how quantum optimal control techniques can be used to both speed up the entanglement generation and increase the fidelity in a realistic setup, whilst respecting typical experimental limitations. For the example of entangling two trapped ion qubits (Lin et al 2013 Nature 504 415), we find an improved fidelity by simply optimizing the polarization of the laser beams utilized in the experiment. More significantly, an alternate combination of transitions between internal states of the ions, when combined with optimized polarization, enables faster entanglement and decreases the error by an order of magnitude.

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“…which is given by the coherence between the hole states i and j in terms of the ion density matrix element, ρ IDM i, j , normalized with respect to the corresponding populations. The simple control mechanism found for argon, of ionizing the 3p 0 orbital and refilling it by excitation from the 3s orbital [32], fails in this case since the 4d 0 and 5s orbitals cannot be coupled by one-photon excitation. Given the Auger lifetime of 2.6 fs for the 4d 0 hole, we restrict our analysis to attosecond photoionization and constrain the pulse duration to a fewhundred attoseconds.…”

Section: Theoretical Frameworkmentioning

confidence: 95%

“…For weak fields, bichromatic control, i.e., the pathway interference between transitions driven by two different photon energies, was discussed in the context of quantum control theory by Shapiro and Brumer [28]. By combining QOCT [27] with the many-body TDCIS method for calculating photoelectron spectra [29,30], quantum interferences among eigenstates involved in the ionization dynamics were exploited specifically for steering photoelectrons [31] and investigating ionic hole coherence in argon [32].…”

Section: Theoretical Frameworkmentioning

confidence: 99%

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Suppression of hole decoherence in ultrafast photoionization

et al. 2020

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In simple one-photon ionization, decoherence occurs due to entanglement between ion and photoelectron. Therefore, the preparation of coherent superpositions of electronic eigenstates of the hole in the photoion is extremely difficult. We demonstrate for the xenon atom that the degree of electronic coherence of the photoion in attosecond photoionization can be enhanced if the influence of many-body interactions is properly controlled. A mechanism at low photon energies involving multiphoton ionization is found, suppressing the loss of coherence through ionization into the same photoelectron partial waves. The degree of coherence found between the 4d 0 and 5s hole states is, on the one hand, limited by Auger decay of the 4d 0 hole. On the other hand, increasing the population ratio such that a significant portion of the state is in a true superposition of both states renders the maximization of the degree of coherence difficult.

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Maximizing hole coherence in ultrafast photoionization of argon with an optimization by sequential parametrization update

Cited by 17 publications

References 45 publications

Attosecond x-ray scattering from a particle-hole wave packet

Attosecond x-ray scattering from a particle-hole wave packet

Quantum optimal control of the dissipative production of a maximally entangled state

Suppression of hole decoherence in ultrafast photoionization

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