Excitation spectra and rf response near the polaron-to-molecule transition from the functional renormalization group

Schmidt, Richard; Enss, Tilman

doi:10.1103/physreva.83.063620

Cited by 153 publications

(242 citation statements)

References 62 publications

Supporting

Mentioning

225

Contrasting

Order By: Relevance

“…This calculation, which is analogous to that of the spin-flip energy in the Nagaoka state of the lattice Hubbard model discussed below, does not account for the finite lifetime of the repulsive polaron. The latter has recently been determined by a functional renormalization group approach [50]. It turns out that in the 'ferromagnetic' regime k F ↑ a > 1.57, the lifetime /Γ is smaller than about 5 /ǫ F ↑ .…”

Section: Absence Of Ferromagnetism For Zero Range Interactionsmentioning

confidence: 99%

Tan relations in one dimension

2011

View full text Add to dashboard Cite

We derive exact relations that connect the universal C/k 4 -decay of the momentum distribution at large k with both thermodynamic properties and correlation functions of two-component Fermi gases in one dimension with contact interactions. The relations are analogous to those obtained by Tan in the three-dimensional case and are derived from an operator product expansion of the one-and two-particle density matrix. They extend earlier results by Olshanii and Dunjko [1] for the bosonic Lieb-Liniger gas. As an application, we calculate the pair distribution function at short distances and the dimensionless contact in the limit of infinite repulsion. The ground state energy approaches a universal constant in this limit, a behavior that also holds in the three-dimensional case. In both one and three dimensions, a Stoner instability to a saturated ferromagnet for repulsive fermions with zero range interactions is ruled out at any finite coupling.

show abstract

Section: Absence Of Ferromagnetism For Zero Range Interactionsmentioning

confidence: 99%

Tan relations in one dimension

2011

View full text Add to dashboard Cite

show abstract

“…In the population-imbalanced case, quasiparticles coined Fermi polarons are the essential building blocks and have been studied in detail experimentally [16] for attractive interactions. Recent theoretical work [9,12,13] has suggested a novel quasiparticle associated with repulsive interactions. The properties of this repulsive polaron are of fundamental importance for the prospects of repulsive many-body states.…”

mentioning

confidence: 99%

Metastability and coherence of repulsive polarons in a strongly interacting Fermi mixture

Kohstall

Zaccanti

Jag

et al. 2012

Nature

509

678

View full text Add to dashboard Cite

Ultracold Fermi gases with tuneable interactions represent a unique test bed to explore the many-body physics of strongly interacting quantum systems [1-4]. In the past decade, experiments have investigated a wealth of intriguing phenomena, and precise measurements of groundstate properties have provided exquisite benchmarks for the development of elaborate theoretical descriptions. Metastable states in Fermi gases with strong repulsive interactions [5-11] represent an exciting new frontier in the field. The realization of such systems constitutes a major challenge since a strong repulsive interaction in an atomic quantum gas implies the existence of a weakly bound molecular state, which makes the system intrinsically unstable against decay. Here, we exploit radio-frequency spectroscopy to measure the complete excitation spectrum of fermionic 40 K impurities resonantly interacting with a Fermi sea of 6 Li atoms. In particular, we show that a welldefined quasiparticle exists for strongly repulsive interactions. For this "repulsive polaron" [9, 12, 13] we measure its energy and its lifetime against decay. We also probe its coherence properties by measuring the quasiparticle residue. The results are well described by a theoretical approach that takes into account the finite effective range of the interaction in our system. We find that a non-zero range of the order of the interparticle spacing results in a substantial lifetime increase. This major benefit for the stability of the repulsive branch opens up new perspectives for investigating novel phenomena in metastable, repulsively interacting fermion systems.Landau's theory of a Fermi liquid [14] and the underlying concept of quasiparticles lay at the heart of our understanding of interacting Fermi systems over a wide range of energy scales, including liquid 3 He, electrons in metals, atomic nuclei, and the quark-gluon plasma. In the field of ultracold Fermi gases, the normal (non-superfluid) phase of a strongly interacting system can be interpreted in terms of a Fermi liquid [15][16][17][18]. In the population-imbalanced case, quasiparticles coined Fermi polarons are the essential building blocks and have been studied in detail experimentally [16] for attractive interactions. Recent theoretical work [9,12,13] has suggested a novel quasiparticle associated with repulsive interactions. The properties of this repulsive polaron are of fundamental importance for the prospects of repulsive many-body states. A crucial question for the feasibility of future experiments is the stability against decay into molecular excitations The vertical lines at 1/(κ F a) = ±1 indicate the width of the strongly interacting regime. The inset illustrates our rf spectroscopic scheme where the impurity is transferred from a noninteracting spin state |0 to the interacting state |1 . [11,12,19]. Indeed, whenever a strongly repulsive interaction is realized by means of a Feshbach resonance [20], a weakly bound molecular state is present into which the system may rapidly decay.Our system consi...

show abstract

“…In nuclear physics, clustering of nucleons leads to the molecule-like structure of nuclei [6]. In condensed matter physics, the structure of quasiparticles is studied in the polaron-molecule transition [7] as well as the molecules associated with the Feshbach resonances in cold atoms [8].…”

Section: Introductionmentioning

confidence: 99%

Structure of near-threshold quasibound states

Kamiya

Hyodo

2016

Phys. Rev. C

View full text Add to dashboard Cite

We study the compositeness of near-threshold quasi-bound states in the framework of effective field theory. From the viewpoint of the low-energy universality, we revisit the model-independent relations between the structure of the bound state and the observables in the weak binding limit. The effective field theory enables us to generalize the weak-binding relation of the stable bound states to unstable quasi-bound states with decay modes. We present the interpretation of the complex values of the compositeness for the unstable states. Combining the model-independent relation and the threshold observables extracted from the experimental data, we show that Λ(1405) is dominated by theKN molecular structure and that a0 (980) is dominated by the non-KK component.

show abstract

Excitation spectra and rf response near the polaron-to-molecule transition from the functional renormalization group

Cited by 153 publications

References 62 publications

Tan relations in one dimension

Tan relations in one dimension

Metastability and coherence of repulsive polarons in a strongly interacting Fermi mixture

Structure of near-threshold quasibound states

Contact Info

Product

Resources

About