Noise correlations in time- and angle-resolved photoemission spectroscopy

Stahl, Christopher; Eckstein, Martin

doi:10.1103/physrevb.99.241111

Cited by 17 publications

(11 citation statements)

References 43 publications

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“…where E k = ξ 2 k + ∆ 2 eq , and T is the temperature. Although this is an imperfect measure of the amount of superconductivity in the system because it only captures the amplitude of the order and not the phase [30], it has shown to be correlated with the spectral gap and its dynamics [24]. There are several differences between the two Methods, which we will now discuss.…”

Section: Methods IImentioning

confidence: 97%

Theory of Time-Resolved Optical Conductivity of Superconductors: Comparing Two Methods for Its Evaluation

2019

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Time-resolved optical conductivity is an oft-used tool to interrogate quantum materials driven out of equilibrium. Theoretically calculating this observable is a complex topic with several approaches discussed in the literature. Using a non-equilibrium Keldysh formalism and a functional derivative approach to the conductivity, we present a comparison of two particular approaches to the calculation of the optical conductivity, and their distinguishing features, as applied to a pumped superconductor. The two methods are distinguished by the relative motion of the probe and gate times; either the probe or gate time is kept fixed while the other is swept. We find that both the methods result in same qualitative features of the time-resolved conductivity after pump is over. However, calculating the conductivity by keeping the gate fixed removes artifacts inherent to the other method. We provide software that, based on data for the first method, is able to construct the second approach.

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Section: Methods IImentioning

confidence: 97%

Theory of Time-Resolved Optical Conductivity of Superconductors: Comparing Two Methods for Its Evaluation

2019

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“…The derivation for the case of a single pulse was discussed in Ref. 18. Here, we describe our derivation for the two nonoverlapping pulses.…”

Section: S1 Derivation Of the Signal In An Experiments With Two Probe...mentioning

confidence: 98%

“…Thus, for the fluctuations ∆I ab p,σ;−p,σ = I In case of a single pulse, the signal has the same form (with all indices A and B being absent) [18], even though the derivation is slightly different due to the fact that all emitted electrons have the same vacuum state. In Eqs.…”

Section: S2 Time Dependence Of Anomalous Green Functions Of a Two-ban...mentioning

confidence: 99%

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Direct detection of odd-frequency superconductivity via time- and angle-resolved photoelectron fluctuation spectroscopy

Kornich,

Schlawin,

Sentef

et al. 2021

Preprint

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We propose a measurement scheme to directly detect odd-frequency superconductivity via time-and angleresolved photoelectron fluctuation spectroscopy. The scheme includes two consecutive, non-overlapping probe pulses applied to a superconducting sample. The photoemitted electrons are collected in a momentum-resolved fashion. Correlations between signals with opposite momenta are analyzed. Remarkably, these correlations are directly proportional to the absolute square of the time-ordered anomalous Green's function of the superconductor. This setup allows for the direct detection of the "hidden order parameter" of odd-frequency pairing. We illustrate this general scheme by concretely analyzing the signal for the prototypical case of two-band superconductors, which are known to exhibit odd-frequency pairing under certain conditions.

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“…This demonstrates how even fluctuating (short range) superconductivity can be experimentally observable. A direct scattering measurement of pairing correlations, analogous to charge or spin density wave order parameters, is more challenging, but noise correlation measurements may be an interesting direction [31] in this regards.…”

Section: (B) Inset)mentioning

confidence: 99%

Electronic and fluctuation dynamics following a quench to the superconducting phase

Stahl,

Eckstein

2020

Preprint

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We investigate the dynamics of superconducting fluctuations in the attractive three-dimensional Hubbard model after a quench from the disordered phase to the ordered regime. While the long time evolution is well understood in terms of dissipative time-dependent Ginzburg-Landau models with unstable potentials, early times are more demanding due to the inseparable dynamics of the pairing fluctuations and the electronic quasiparticles. Our simulation using the time-dependent fluctuation exchange approximation treat both degrees of freedom on the same footing and reveal a non-thermal electronic regime causing a non-monotonous growth of the fluctuations. This feature is not directly captured from the Ginzburg-Landau theory, but nevertheless remains observable beyond the thermalization time of the electrons. We further explore how the growth of the order parameter fluctuations leads to an opening of a pseudo-gap in the electronic spectrum, and identify Andreev reflections as the dominant mechanism behind the gap opening.

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Noise correlations in time- and angle-resolved photoemission spectroscopy

Cited by 17 publications

References 43 publications

Theory of Time-Resolved Optical Conductivity of Superconductors: Comparing Two Methods for Its Evaluation

Theory of Time-Resolved Optical Conductivity of Superconductors: Comparing Two Methods for Its Evaluation

Direct detection of odd-frequency superconductivity via time- and angle-resolved photoelectron fluctuation spectroscopy

Electronic and fluctuation dynamics following a quench to the superconducting phase

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