Quasiparticle Lifetime of the Repulsive Fermi Polaron

Adlong, Haydn S.; Liu, Weizhe Edward; Scazza, Francesco; Zaccanti, Matteo; Oppong, Nelson Darkwah; Fölling, Simon; Parish, Meera M.; Levinsen, Jesper

doi:10.1103/physrevlett.125.133401

Cited by 49 publications

(81 citation statements)

References 57 publications

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“…By taking into account the crucial role of momentum-average, we have successfully explained the measured ejection rf spectrum of a unitary Fermi polaron at low temperatures (i.e., T < 0.5T F ) from the MIT group [20]. We have also resolved a puzzling discrepancy between theory and experiment for the quasiparticle lifetime of repulsive polarons, observed in a recent experiment at LENS [19,44].…”

Section: Conclusion and Outlooksmentioning

confidence: 56%

“…A refined theoretical treatment is therefore needed. For the low-temperature measurement of repulsive Fermi polarons at European Laboratory for Non-Linear Spectroscopy (LENS) [19], we show that the decay rate determined from Rabi oscillations cannot be theoretically explained solely by considering the decay rate of zero-momentum repulsive polarons even at nonzero temperature [44]. It can be quantitatively understood, only when we take into account the momentum average in the impurity spectral function.…”

Section: Introductionmentioning

confidence: 92%

“…At the interaction parameter 1/(k F a) < 1, the measured decay rate is significantly larger than the theoretical prediction. In a recent theoretical simulation [44], a finite-temperature variational approach has been used to simulate the realtime dynamics of Rabi oscillations. However, the simulation is carried out at zero momentum and hence yields a similar prediction from the finite-temperature Chevy's ansatz (see, i.e., the thick red dashed line at 0.10T F ).…”

Section: Injection Rf-spectroscopy Of Repulsive Polaronsmentioning

confidence: 99%

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Fermi polarons at finite temperature: Spectral function and rf-spectroscopy

Hu,

Liu

2022

Preprint

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We present a systematic study of a mobile impurity immersed in a three-dimensional Fermi sea of fermions at finite temperature, by using the standard non-self-consistent many-body T -matrix theory that is equivalent to a finite-temperature variational approach with the inclusion of one-particlehole excitation. The impurity spectral function is determined in the real-frequency domain, avoiding any potential errors due to the numerical analytic continuation in previous T -matrix calculations and the small spectral broadening parameter used in variational calculations. In the weak-coupling limit, we find that the quasiparticle decay rate of both attractive and repulsive polarons does not increase significantly with increasing temperature, and therefore Fermi polarons may remain welldefined far above Fermi degeneracy. In contrast, near the unitary limit with strong coupling, the decay rate of Fermi polarons rapidly increase and the quasiparticle picture breaks down close to the Fermi temperature. We analyze in detail the recent ejection and injection radio-frequency (rf) spectroscopy measurements, performed at Massachusetts Institute of Technology (MIT) and at European Laboratory for Non-Linear Spectroscopy (LENS), respectively. We show that the momentum average of the spectral function, which is necessary to account for the observed rfspectroscopy, has a sizable contribution to the width of the quasiparticle peak in spectroscopy. As a result, the measured decay rate of Fermi polarons could be significantly larger than the calculated quasiparticle decay rate at zero momentum. By take this crucial contribution into account, we find that there is a reasonable agreement between theory and experiment for the lifetime of Fermi polarons in the strong-coupling regime, as long as they remain well-defined.

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Section: Conclusion and Outlooksmentioning

confidence: 56%

Section: Introductionmentioning

confidence: 92%

Section: Injection Rf-spectroscopy Of Repulsive Polaronsmentioning

confidence: 99%

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Fermi polarons at finite temperature: Spectral function and rf-spectroscopy

Hu,

Liu

2022

Preprint

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“…In particular, the emergence of new quasiparticles, the so-called Fermi-polaron-polaritons have been observed [49]. They can be roughly described as a coherent superposition of photons and Fermi polarons, which are formed by the polaritons interacting with the surrounding electron gas (2DEG) in analogy with what is observed in atomic gases [50][51][52][53][54][55][56][57].…”

Section: Introductionmentioning

confidence: 98%

Polaritons in an electron gas -- quasiparticles and Landau effective interactions

Bastarrachea-Magnani,

Thomsen,

Camacho-Guardian

et al. 2021

Preprint

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Two-dimensional semiconductors inside optical microcavities have emerged as a versatile platform to explore new hybrid light-matter quantum states. The strong light-matter coupling leads to the formation of exciton-polaritons, which in turn interact with the surrounding electron gas to form quasiparticles called polaron-polaritons. Here, we develop a general microscopic framework to calculate the properties of these quasiparticles such as their energy and the interactions between them. From this, we give microscopic expressions for the parameters entering a Landau theory for the polaron-polaritons, which offers a simple yet powerful way to describe such interacting lightmatter many-body systems. As an example of the application of our framework, we then use the ladder approximation to explore the properties of the polaron-polaritons. We furthermore show that they can be measured in a non-demolition way via the light transmission/reflection spectrum of the system. Finally, we demonstrate that the Landau effective interaction mediated by electronhole excitations is attractive leading to red shifts of the polaron-polaritons. Our work provides a systematic framework to study exciton-polaritons in electronically doped two-dimensional materials such as novel van der Waals heterostructures.

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“…In particular, the emergence of new quasiparticles, the so-called Fermipolaron-polaritons have been observed [49]. They can be roughly described as a coherent superposition of photons and Fermi polarons, which are formed by the polaritons interacting with the surrounding electron gas (2DEG) in analogy with what is observed in atomic gases [50][51][52][53][54][55][56][57].…”

Section: Introductionmentioning

confidence: 99%

Polaritons in an Electron Gas—Quasiparticles and Landau Effective Interactions

Bastarrachea-Magnani

Thomsen

Camacho-Guardián

et al. 2021

Atoms

View full text Add to dashboard Cite

Two-dimensional semiconductors inside optical microcavities have emerged as a versatile platform to explore new hybrid light–matter quantum states. A strong light–matter coupling leads to the formation of exciton-polaritons, which in turn interact with the surrounding electron gas to form quasiparticles called polaron-polaritons. Here, we develop a general microscopic framework to calculate the properties of these quasiparticles, such as their energy and the interactions between them. From this, we give microscopic expressions for the parameters entering a Landau theory for the polaron-polaritons, which offers a simple yet powerful way to describe such interacting light–matter many-body systems. As an example of the application of our framework, we then use the ladder approximation to explore the properties of the polaron-polaritons. Furthermore, we show that they can be measured in a non-demolition way via the light transmission/reflection spectrum of the system. Finally, we demonstrate that the Landau effective interaction mediated by electron-hole excitations is attractive leading to red shifts of the polaron-polaritons. Our work provides a systematic framework to study exciton-polaritons in electronically doped two-dimensional materials such as novel van der Waals heterostructures.

show abstract

Quasiparticle Lifetime of the Repulsive Fermi Polaron

Cited by 49 publications

References 57 publications

Fermi polarons at finite temperature: Spectral function and rf-spectroscopy

Fermi polarons at finite temperature: Spectral function and rf-spectroscopy

Polaritons in an electron gas -- quasiparticles and Landau effective interactions

Polaritons in an Electron Gas—Quasiparticles and Landau Effective Interactions

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