Polarons in a dipolar condensate

Kain, Ben; Ling, Hong Y.

doi:10.1103/physreva.89.023612

Phys. Rev. A

2014

DOI: 10.1103/physreva.89.023612

|View full text |Cite

Polarons in a dipolar condensate

Ben Kain

Hong Y. Ling

Abstract: We consider a polaronic model in which impurity fermions interact with background bosons in a dipolar condensate. The polaron in this model emerges as an impurity dressed with a cloud of phonons of the dipolar condensate, which, due to the competition between the attractive and repulsive parts of the dipole-dipole interaction, obey an anisotropic dispersion spectrum. We study how this anisotropy affects theČerenkov-like emission of Bogoliubov phonon modes, which can be directly verified by experiments in which… Show more

Help me understand this report

View preprint versions

Search citation statements

Order By: Relevance

Paper Sections

Select...

Citation Types

Supporting

Mentioning

Contrasting

Year Published

2014

2023

Publication Types

Select...

Article6

Relationship

Self Cite0

Independent6

Authors

Journals

Cited by 48 publications

(53 citation statements)

References 80 publications

(110 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This typical timescale is associated with the oscillation period of observables as predicted by Bogoliubov theory [1,4,[9][10][11]. We see that as long as t ≪ τ interm (k), we can ignore the damping, and the system behaves as if it were described by Bogoliubov theory and its variants.…”

mentioning

confidence: 99%

“…Equally of interest is the nature of metastable states, (often) so produced. Considerable theoretical attention has gone into this subject, albeit characterizing the post-quench physics entirely in terms of oscillatory behavior [4,6,7,[9][10][11].How long do these oscillations persist and how does ultimate equilibration proceed for different momentum states is a complicated problem that is the focus of the present paper. Here we discuss the different time scales associated with dissipation and equilibration in the context of the evolution of the momentum distribution n k for a three-dimensional Bose gas.…”

mentioning

confidence: 99%

“…Indeed, it has been argued that the same should apply to quenched Bose gases, through use of the number equation [9,11]. In this way the condensate dynamics are derived from, and therefore somewhat secondary to that of the excitations.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Equilibrating dynamics in quenched Bose gases: Characterizing multiple time regimes

Rançon

Levin

2014

Phys. Rev. A

View full text Add to dashboard Cite

We address the physics of equilibration in ultracold atomic gases following a quench of the interaction parameter. Our work is based on a bath model which generates damping of the bosonic excitations. We illustrate this dissipative behavior through the momentum distribution of the excitations, n k , observing that larger k modes have shorter relaxation times τ (k); they will equilibrate faster, as has been claimed in recent experimental work. We identify three time regimes. At short times n k exhibits oscillations; these are damped out at intermediate times where the system appears to be in a false or slowly converging equilibrium. Finally, at longer times, full equilibration occurs. This false-equilibrium is, importantly, associated with the k dependence in τ (k) and has implications for experiment.PACS numbers: 03.75. Kk, 47.37.+q, 43.20.Ks Introduction-Recent interaction quench experiments in cold bosonic gases are providing unique perspectives into the behavior of out-of-equilibrium dynamics of quantum systems [1][2][3][4][5]. These perspectives were hitherto not available in the quantum fluids of condensed matter. The extent to which equilibrium is accessible and the time constants for equilibration are all open questions. Equally of interest is the nature of metastable states, (often) so produced. Considerable theoretical attention has gone into this subject, albeit characterizing the post-quench physics entirely in terms of oscillatory behavior [4,6,7,[9][10][11].How long do these oscillations persist and how does ultimate equilibration proceed for different momentum states is a complicated problem that is the focus of the present paper. Here we discuss the different time scales associated with dissipation and equilibration in the context of the evolution of the momentum distribution n k for a three-dimensional Bose gas. While we use a specific bath model to derive detailed results for n k (t), our central results can almost be anticipated by making use of empirical observations in previous quench experiments [4,5]. As emphasized in both experiments, the equilibration dynamics is rather strongly dependent on the momentum of the state under consideration. An unpublished analysis [12] of the experiments in Ref. 4, led to the conclusion that damping at large momentum had to be included. Also notable is the claim that "it is perhaps not unexpected that higher momenta dynamics saturate faster" [5]. This demonstration that large momentum k, high energy, states equilibrate more rapidly than those at small k is the aim of this paper. It leads to a multistep equilibration process, assuming, as is reasonable, that the condensate also evolves in time as the system re-equilibrates.The important point at issue is that the relaxation times τ (k) disperse with k. At some intermediate time after the quench, there will always be higher energy k states which will be able to follow quasi-adiabatically the (necessarily) slower relaxation of the condensate. But lower energy states, as well as the condensate, will not

show abstract

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Equilibrating dynamics in quenched Bose gases: Characterizing multiple time regimes

Rançon

Levin

2014

Phys. Rev. A

View full text Add to dashboard Cite

show abstract

“…(1) up to a factor of order unity, lending it further credence. 2 For previous studies of superfluids and BEC in cosmology see [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. See note at the end for more information.…”

mentioning

confidence: 99%

Dark matter and dark energy from a Bose–Einstein condensate

Das

Bhaduri

2015

Class. Quantum Grav.

View full text Add to dashboard Cite

We show that Dark Matter consisting of bosons of mass of about 1 eV or less has critical temperature exceeding the temperature of the universe at all times, and hence would have formed a Bose-Einstein condensate at very early epochs. We also show that the wavefunction of this condensate, via the quantum potential it produces, gives rise to a cosmological constant which may account for the correct dark energy content of our universe. We argue that massive gravitons or axions are viable candidates for these constituents. In the far future this condensate is all that remains of our universe.The basic contents of our universe in terms of Dark Matter (DM), Dark Energy (DE), visible matter and radiation, and also its accelerated expansion in recent epochs has been firmly established by a number of observations now [1][2][3][4]. However although DM constitutes about 25% and DE about 70% of all matter-energy content, the constituents of DM and the origin of a tiny cosmological constant, or DE, of the order of 10 −123 in Planck units, which drives this acceleration, remains to be understood. In this paper we show that if DM is assumed to consist of a gas of bosons of mass m, then for m ≤ 1eV , the critical temperature below which they will form a Bose-Einstein condensate (BEC) exceeds the temperature of the universe at all times. Therefore they would form such a condensate at very early epochs, in which a macroscopic fraction of the bosons fall to the ground state with little or no momentum and zero pressure, and therefore may be considered as viable candidates for cold DM (CDM). Further, via the quantum potential that it produces, the macroscopic wavefunction of the condensate gives rise to a positive cosmological constant in the Friedmann equation, whose magnitude depends on m, and for m ≃ 10 −32 eV , one obtains the observed value of the cosmological constant. Therefore bosons with this tiny mass can account for both DM and DE in our universe. We argue that massive gravitons or axions are viable candidates for these bosons. Finally we speculate on the ultimate fate of our universe, and end with some open problems.To compute the critical temperature of an ideal gas of bosons constituting DM, we first note that these must have a mass, however small, and with average interparticle distances (N/V ) −1/3 (where N = total number of bosons in volume V ) comparable or smaller than the * email: saurya.das@uleth.ca † email: bhaduri@physics.mcmaster.ca thermal de Broglie wavelength hc/k B T , such that quantum effects start to dominate. Identifying this temperature of a bosonic gas to the critical temperature T c (below which the condensate forms) we get k B T c ≃ hc(N/V ) 1/3 . A more careful calculation for ultra-relativistic noninteracting bosons with a tiny mass gives [5][6][7] In the above N = N B + N R , N B being the number of bosons in the BEC, and N R outside it, both consisting of bosons of small mass as discussed earlier, η is the polarization factor and ζ(3) ≈ 1.2. Also a is the cosmological scale factor, L = L 0 a i...

show abstract

Breakdown of the Fermi polaron description near Fermi degeneracy at unitarity

Mulkerin

Liu

2019

Annals of Physics

View full text Add to dashboard Cite

We theoretically investigate attractive and repulsive Fermi polarons in three dimensions at finite temperature and impurity concentration through the many-body T -matrix theory and hightemperature virial expansion. By using the analytically continued impurity Green's function, we calculate the direct rf spectroscopy of attractive polarons in the unitary regime. Taking the peak value of the rf spectroscopy as the polaron energy and the full width half maximum as the polaron lifetime, we determine the temperature range of validity for the quasi-particle description of Fermi polarons in the unitary limit. We also explore the temperature and impurity dependence of attractive and repulsive Fermi polarons using the direct and reverse rf spectroscopy. This methodology allows us to directly compare our results to the recent experimental data from the European Laboratory for Non-Linear Spectroscopy [F. Scazza et al., Phys. Rev. Lett. 118, 083602 (2017)].

show abstract

scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.

Contact Info

hi@scite.ai

10624 S. Eastern Ave., Ste. A-614

Henderson, NV 89052, USA

Blog Terms and Conditions API Terms Privacy Policy Contact Cookie Preferences Do Not Sell or Share My Personal Information

Made with 💙 for researchers

Part of the Research Solutions Family.

Polarons in a dipolar condensate

Cited by 48 publications

References 80 publications

Equilibrating dynamics in quenched Bose gases: Characterizing multiple time regimes

Equilibrating dynamics in quenched Bose gases: Characterizing multiple time regimes

Dark matter and dark energy from a Bose–Einstein condensate

Breakdown of the Fermi polaron description near Fermi degeneracy at unitarity

Contact Info

Product

Resources

About