Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Journal of Chemical Biological and Physical Sciences

A theoretical study of Dynamic Structure factor and evaluation of impurity scattering rate, dispersion relation of collective mode and Spectral density of a Fermi super fluid along the BCS-BEC crossover region

Published Apr 30, 2018• 1 citation
Publisher

Abstract

Using the theoretical formalism of T. H. Johnson etal.[PRL,116,240403 (2016)], Y. Nishida [PRL 114, 115302 (2015)], W. Yi and X. Chi[Phys.Rev. A92, 013623 (2015)] and A. Sindona etal.[PRL 111, 165303 (2013)], we have theoretically evaluated the dynamic structure factor (DSF) and spectral density of Fermi super fluid along BCS-BEC crossover regime.The evaluation is based on a model in which an impurity atom is trapped by an anharmonic potential with attractive interaction.We have evaluated impurity decay rate 4 (10 ) F E   as a function of vibrational energy A F E  for BCS limit ( 1 Fs ka =-0.5), unitarity limit ( 1 Fs ka =0.0) and BEC limit ( 1 Fs ka =1.0) respectively.Our theoretically obtained results show that

DOI
10.24214/jcbps.c.8.3.23355

Related papers

AN EVALUATION OF SUPER-FLUID DENSITY s AS A FUNCTION OF c T T FOR BCS-BEC CROSSOVER REGIME

Amitesh Kumar, Verma Rk

In a Fermi gas with a Fashbach resonance, one can tune the strengthof the paring interaction by adjusting the threshold energy of Feshbachresonance. The super-fluid density s is always equal to the total carrierdensity  at T  0 which it vanishes at the super-fluid phase transition c T .These properties are satisfied in both Fermi and Bose super-fluid. There is acrucial difference between s in a Fermi superfluid and that in a Bose superfluid.In a mean field BCS theory originates from the thermal dissociationof cooper pairs.There it was observed that that if one increases the strength of thepairing interaction BCS type normal fluid density dominated by quasi-particleexcitation change into BES type normal fluid density dominated byBogoliubov collective excitations. As super-fluid density s plays animportant role in two fluid hydrodynamics these evaluated results would beuseful in the study of dynamical properties in the BCS-BEC crossover regionat finite temperature.

THE SCIENTIFIC TEMPER•Jul 25, 2019•0 citations

Probing the dynamic structure factor of a neutral Fermi superfluid along the BCS-BEC crossover using atomic impurity qubits

Mark T. Mitchison, T. H. Johnson, Dieter Jaksch

We study an impurity atom trapped by an anharmonic potential, immersed within a cold atomic Fermi gas with attractive interactions that realizes the crossover from a Bardeen-Cooper-Schrieffer superfluid to a Bose-Einstein condensate. Considering the qubit comprising the lowest two vibrational energy eigenstates of the impurity, we demonstrate that its dynamics probes the equilibrium density fluctuations encoded in the dynamic structure factor of the superfluid. Observing the impurity's evolution is thus shown to facilitate nondestructive measurements of the superfluid order parameter and the contact between collective and single-particle excitation spectra. Our setup constitutes a model of an open quantum system interacting with a thermal reservoir, the latter supporting both bosonic and fermionic excitations that are also coupled to each other.

arXiv:1609.08131•Physical Review A•Dec 16, 2016•14 citations

Dynamic structure factor of a Fermi superfluid in the BEC-BCS crossover

Tarun Kanti Ghosh

We consider cigar-shaped Fermi superfluid in the Bose-Einstein condensation (BEC)-BCS crossover. Using the polytropic form of equation of state, we derive low energy multibranch bosonic excitations and the corresponding density fluctuations in three different regimes along the crossover, namely weak-coupling BCS, unitarity, and molecular BEC regimes. Bragg spectroscopy can be used to probe the multibranch nature of the low-energy bosonic excitations by measuring the dynamic structure factor. Therefore we calculate the dynamic structure factor in those three different regimes. In Bragg spectroscopy, an actual observable is momentum imparted to the superfluid due to the Bragg potential. We also present results of the momentum imparted to the superfluid due to the Bragg pulses.

arXiv:0707.3927•Physical Review A•Sep 7, 2007•9 citations

Dynamic structure factor of a strongly correlated Fermi superfluid within a density functional theory approach

Peng Zou, F. Dalfovo, Rishi Sharma +2 more

We theoretically investigate the dynamic structure factor of a strongly interacting Fermi gas at the crossover from Bardeen–Cooper–Schrieffer superfluids to Bose–Einstein condensates, by developing an improved random phase approximation within the framework of a density functional theory (DFT)—the so-called superfluid local density approximation. Compared with the previous random-phase-approximation studies based on the standard Bogoliubov–de Gennes equations, the use of the DFT greatly improves the accuracy of the equation of state at the crossover, and leads to a better description of both collective Bogoliubov-Anderson-Goldstone phonon mode and single-particle fermionic excitations at small transferred momentum. Near unitarity, where the s -wave scattering length diverges, we show that the single-particle excitations start to significantly contribute to the spectrum of dynamic structure factor once the frequency is above a threshold of the energy gap at . The sharp rise in the spectrum at this threshold can be utilized to measure the pairing gap Δ. Together with the sound velocity determined from the phonon branch, the dynamic structure factor provides us some key information of the crossover Fermi superfluid. Our predictions could be examined in experiments with 6 Li or 40 K atoms using Bragg spectroscopy.

arXiv:1608.08795•New Journal of Physics•Nov 24, 2016•11 citations

Study of BCS-BEC Crossover Physics and Evaluation of Energy Gap Parameters and Chemical Potential from BCS-Theory

Lekha Singh, L. K. Mishra

Using the theoretical formalism of C. Regal et al. PRL (2004), we have studied the BCS-BEC crossover regime. We have evaluated the value of energy gap parameter and chemical potential for the crossover as a function of dimensionless parameters |KF as| -1 from BCS-theory. Our theoretical result indicates that the crossover occurs in the very small region of the parameter-1< |KF as| -1 < 1.

International Journal of Chemical Sciences•Jan 1, 2011•0 citations

BCS–BEC crossover in a trapped Fermi super-fluid using a density-functional equation

Sadhan K. Adhikari

We derive a generalized time-dependent Galilean-invariant density-functional (DF) equation appropriate to study the stationary and non-stationary properties of a trapped Fermi super-fluid in the Bardeen–Cooper–Schrieffer (BCS) to Bose–Einstein condensation (BEC) crossover. This equation is equivalent to a quantum hydrodynamical equation for a Fermi super-fluid. The bulk chemical potential of this equation has the proper (model-independent) dependence on the Fermi–Fermi scattering length in the BCS and BEC limits. We apply this DF equation to the study of the stationary density profile and size of a cigar-shaped Fermi super-fluid of 6 Li atoms, and the results are in good agreement with the experiment of Bartenstein et al in the BCS–BEC crossover. We also apply the DF equation to the study of axial and radial breathing oscillation and our results for these frequencies are in good agreement with experiments in the BCS–BEC crossover.

arXiv:1003.1712•Journal of Physics B Atomic Molecular and Optical Physics•Apr 6, 2010•19 citations
Using the theoretical formalism of T. H. Johnson etal.[PRL,116,240403 (2016)], Y. Nishida [PRL 114, 115302 (2015)], W. Yi and X. Chi[Phys.Rev. A92, 013623 (2015)] and A. Sindona etal.[PRL 111, 165303 (2013)], we have theoretically evaluated the dynamic structure factor (DSF) and spectral density of Fermi super fluid along BCS-BEC crossover regime.The evaluation is based on a model in which an impurity atom is trapped by an anharmonic potential with attractive interaction.We have evaluated impurity decay rate 4 (10 ) F E   as a function of vibrational energy A F E  for BCS limit ( 1 Fs ka =-0.5), unitarity limit ( 1 Fs ka =0.0) and BEC limit ( 1 Fs ka =1.0) respectively.Our theoretically obtained results show that
In a Fermi gas with a Fashbach resonance, one can tune the strengthof the paring interaction by adjusting the threshold energy of Feshbachresonance. The super-fluid density s is always equal to the total carrierdensity  at T  0 which it vanishes at the super-fluid phase transition c T .These properties are satisfied in both Fermi and Bose super-fluid. There is acrucial difference between s in a Fermi superfluid and that in a Bose superfluid.In a mean field BCS theory originates from the thermal dissociationof cooper pairs.There it was observed that that if one increases the strength of thepairing interaction BCS type normal fluid density dominated by quasi-particleexcitation change into BES type normal fluid density dominated byBogoliubov collective excitations. As super-fluid density s plays animportant role in two fluid hydrodynamics these evaluated results would beuseful in the study of dynamical properties in the BCS-BEC crossover regionat finite temperature.
We study an impurity atom trapped by an anharmonic potential, immersed within a cold atomic Fermi gas with attractive interactions that realizes the crossover from a Bardeen-Cooper-Schrieffer superfluid to a Bose-Einstein condensate. Considering the qubit comprising the lowest two vibrational energy eigenstates of the impurity, we demonstrate that its dynamics probes the equilibrium density fluctuations encoded in the dynamic structure factor of the superfluid. Observing the impurity's evolution is thus shown to facilitate nondestructive measurements of the superfluid order parameter and the contact between collective and single-particle excitation spectra. Our setup constitutes a model of an open quantum system interacting with a thermal reservoir, the latter supporting both bosonic and fermionic excitations that are also coupled to each other.
We consider cigar-shaped Fermi superfluid in the Bose-Einstein condensation (BEC)-BCS crossover. Using the polytropic form of equation of state, we derive low energy multibranch bosonic excitations and the corresponding density fluctuations in three different regimes along the crossover, namely weak-coupling BCS, unitarity, and molecular BEC regimes. Bragg spectroscopy can be used to probe the multibranch nature of the low-energy bosonic excitations by measuring the dynamic structure factor. Therefore we calculate the dynamic structure factor in those three different regimes. In Bragg spectroscopy, an actual observable is momentum imparted to the superfluid due to the Bragg potential. We also present results of the momentum imparted to the superfluid due to the Bragg pulses.
We theoretically investigate the dynamic structure factor of a strongly interacting Fermi gas at the crossover from Bardeen–Cooper–Schrieffer superfluids to Bose–Einstein condensates, by developing an improved random phase approximation within the framework of a density functional theory (DFT)—the so-called superfluid local density approximation. Compared with the previous random-phase-approximation studies based on the standard Bogoliubov–de Gennes equations, the use of the DFT greatly improves the accuracy of the equation of state at the crossover, and leads to a better description of both collective Bogoliubov-Anderson-Goldstone phonon mode and single-particle fermionic excitations at small transferred momentum. Near unitarity, where the s -wave scattering length diverges, we show that the single-particle excitations start to significantly contribute to the spectrum of dynamic structure factor once the frequency is above a threshold of the energy gap at . The sharp rise in the spectrum at this threshold can be utilized to measure the pairing gap Δ. Together with the sound velocity determined from the phonon branch, the dynamic structure factor provides us some key information of the crossover Fermi superfluid. Our predictions could be examined in experiments with 6 Li or 40 K atoms using Bragg spectroscopy.
We derive a generalized time-dependent Galilean-invariant density-functional (DF) equation appropriate to study the stationary and non-stationary properties of a trapped Fermi super-fluid in the Bardeen–Cooper–Schrieffer (BCS) to Bose–Einstein condensation (BEC) crossover. This equation is equivalent to a quantum hydrodynamical equation for a Fermi super-fluid. The bulk chemical potential of this equation has the proper (model-independent) dependence on the Fermi–Fermi scattering length in the BCS and BEC limits. We apply this DF equation to the study of the stationary density profile and size of a cigar-shaped Fermi super-fluid of 6 Li atoms, and the results are in good agreement with the experiment of Bartenstein et al in the BCS–BEC crossover. We also apply the DF equation to the study of axial and radial breathing oscillation and our results for these frequencies are in good agreement with experiments in the BCS–BEC crossover.