Inducing Resonant Interactions in Ultracold Atoms with a Modulated Magnetic Field

Smith, D. Hudson

doi:10.1103/physrevlett.115.193002

Cited by 15 publications

(20 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, the equation for the static case looks just as the one for the dynamic situation, however since there are no neighbor chains to couple to, it couples with itself. Simple algebra yields This definite integral can be calculated exactly, reproducing the result obtained above in equation (28). Figure 7 illustrates how the low frequency limit is approached for the case of  = -0.5.…”

Section: Low Frequencysupporting

confidence: 61%

“…Our results can be generalized to continuous systems by taking the lattice constant of the tight binding model to zero. The continuum case is also interesting beyond impurity physics to describe the effective two-body interaction between atoms in a one-dimensional gas, which is subject to an oscillating Feshbach resonance [28]. We obtain the exact transmission probability through the impurity based on the Floquet formalism [29][30][31], which allows for a treatment beyond the perturbative regime.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Transport through an AC-driven impurity: Fano interference and bound states in the continuum

et al. 2017

View full text Add to dashboard Cite

Using the Floquet formalism we study transport through an AC-driven impurity in a tight binding chain. The results obtained are exact and valid for all frequencies and barrier amplitudes. At frequencies comparable to the bulk bandwidth we observe a breakdown of the transmission T=0 which is related to the phenomenon of Fano resonances associated to AC-driven bound states in the continuum. We also demonstrate that the location and width of these resonances can be modified by tuning the frequency and amplitude of the driving field. At high frequencies there is a close relation between the resonances and the phenomenon of coherent destruction of tunneling. As the frequency is lowered no more resonances are possible below a critical value and the results approach a simple time average of the static transmission. J n j J J n New J. Phys. 19 (2017) 043029 S A Reyes et al 4.3. Inhomogeneous coupling to the impurity site ¢ ¹ J J Let us now go back to the tight binding model in order to explore what happens when we consider a different coupling to the impurity site ( ¢ ¹ J J ) corresponding to physical realizations where the coupling to the driven impurity may also differ from the ones along the chain.In figure 5 we show results for the transmission for a weaker hopping amplitude ¢ = J J 0.9 . While there are similarities to the homogeneous case discussed above, the resonances now start at a finite value of m > 0 according to equation (17). As can clearly be seen in the bottom part of figure 5 for w = J 3 accordingly there is a dip but no resonance for m = J , while the resonance at m = J 3 is relatively sharp. As shown in figure 6 (top) for larger hopping amplitude ¢ = J J 2 we observe a general increase in transmission across the parameter space and the resonances move to higher frequencies for a given energy of the incoming wave following equation (16). Correspondingly, the resonances are also displaced in energy at fixed frequency w = J 3 as shown in figure 6 (bottom). These features can be interpreted nicely by using the Fano resonances due to the 'side-attached' systems explained above and depicted in figure 2. It turns out that the two resonances we observe in figures 5 and 6 are Figure 4. Transmission coefficient in the limit of vanishing lattice spacing for  ¢ = 1 in units of 1/2m, i.e. for a quadratic dispersion relation with a local driving in form of a delta-function. 6 New J. Phys. 19 (2017) 043029 S A Reyes et alFigure 5. Transmission coefficient for modified coupling ¢ = J J 0.9 . Top: for a fixed energy  = -J 0.5 as a function of μ and ω. The dashed lines depict the analytic approximations for the location of the resonances at high frequencies (green), and close to where they emerge (red) from equation (15). Bottom: for fixed frequency w = J 3 .Figure 6. Transmission coefficient for modified coupling ¢ = J J 2 . Top: for a fixed energy  = -J 0.5 as a function of μ and ω. The red dashed lines depict the analytic approximations for the location of the resonances close to where they emerge from equation ...

show abstract

Section: Low Frequencysupporting

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Transport through an AC-driven impurity: Fano interference and bound states in the continuum

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Techniques involving radio-frequency (RF) magnetic fields are of exceptional importance since they are highly adjustable in experiments [4,5]. Indeed, the additional magnetic RF field modulation enables the investigation of cold molecule formation [6][7][8] or heteronuclear association/dissociation processes in a microgravity environment [9], association of Efimov trimers [10][11][12][13] or manipulation of Feshbach collisions [14][15][16]. Beyond cold physics, external fields are also used in ultrafast physics where short laser pulses probe photoionization processes [17].…”

mentioning

confidence: 99%

Nonadiabatic Molecular Association in Thermal Gases Driven by Radio-Frequency Pulses

et al. 2019

View full text Add to dashboard Cite

The molecular association process in a thermal gas of 85 Rb is investigated where the effects of the envelope of the radio-frequency field are taken into account. For experimentally relevant parameters our analysis shows that with increasing pulse length the corresponding molecular conversion efficiency exhibits low-frequency interference fringes which are robust under thermal averaging over a wide range of temperatures. This dynamical interference phenomenon is attributed to Stückelberg phase accumulation between the low-energy continuum states and the dressed molecular state which exhibits a shift proportional to the envelope of the radio-frequency pulse intensity.External fields are widely used in order to probe, tune and control various aspects of atomic matter. For example, in the field of ultracold atomic physics dc magnetic fields constitute the main experimental means for the creation and manipulation of molecules via Feshbach resonances [1][2][3]. Techniques involving radio-frequency (RF) magnetic fields are of exceptional importance since they are highly adjustable in experiments [4,5]. Indeed, the additional magnetic RF field modulation enables the investigation of cold molecule formation [6][7][8] or heteronuclear association/dissociation processes in a microgravity environment [9], association of Efimov trimers [10][11][12][13] or manipulation of Feshbach collisions [14][15][16]. Beyond cold physics, external fields are also used in ultrafast physics where short laser pulses probe photoionization processes [17]. In such systems the pulse envelope plays a crucial role since it induces a time-dependent AC-Stark shift of the energy levels of the system whereas the light-pulse derivatives yield a dynamic interference in photoionization cross-sections [18][19][20][21][22][23][24][25], [26].In this letter, the RF-induced association process in an ultracold thermal gas is investigated and it is shown that the RF field envelope plays a crucial role. This allows us to extend the concept of dynamical interference in strong field ionization into the realm of ultracold physics and to explore its impact on the production of cold molecules. In Ref.[7] experimental evidences suggested that RF association in a thermal gas can exhibit Rabi-like oscillations in the molecular conversion efficiency (MCE) as a function of the duration of the RF field. On the other hand, the corresponding theoretical studies in Ref. [6] show that in this range of parameters any coherence in the MCE is completely smeared out by thermal averaging. Evidently, these studies still pose an intriguing question for the RF association processes in thermal gases: Under what con-ditions does the RF molecule formation display interference fringes that survive thermal averaging? Our study tackles this question: a gas of 85 Rb atoms with density n = 10 11 cm 3 is considered for which the gas temperature varies from T = 20 nK up to T = 50 nK , and for an RF field driving frequency that can associate continuum states near the dissociation threshold. In t...

show abstract

“…Such an ambiguity at O(∂ 2 ) is however irrelevant to our discussion below as long as hydrodynamics up to first order in derivatives is concerned [see Eqs. (20) and (44)].…”

Section: B Continuity Equationsmentioning

confidence: 99%

“…In addition, an interparticle interaction is not only tunable in its magnitude and sign with the magnetic field via Feshbach resonances [6], but also variable over space and time at will to a reasonable extent [7][8][9]. While such a spacetime-dependent scattering length has been proposed to realize a number of intrigu-ing phenomena [10][11][12][13][14][15][16][17][18][19][20], it may also be useful as a novel probe of target systems.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamics with spacetime-dependent scattering length

Fujii

Nishida

2018

Phys. Rev. A

View full text Add to dashboard Cite

Hydrodynamics provides a concise but powerful description of long-time and long-distance physics of correlated systems out of thermodynamic equilibrium. Here we construct hydrodynamic equations for nonrelativistic particles with a spacetime-dependent scattering length and show that it enters constitutive relations uniquely so as to represent the fluid expansion and contraction in both normal and superfluid phases. As a consequence, we find that a leading dissipative correction to the contact density due to the spacetime-dependent scattering length is proportional to the bulk viscosity (ζ2 in the superfluid phase). Also, when the scattering length is slowly varied over time in a uniform system, the entropy density is found to be produced even without fluid flows in proportion to the bulk viscosity, which may be useful as a novel probe to measure the bulk viscosity in ultracold-atom experiments. CONTENTS

show abstract

Inducing Resonant Interactions in Ultracold Atoms with a Modulated Magnetic Field

Cited by 15 publications

References 25 publications

Transport through an AC-driven impurity: Fano interference and bound states in the continuum

Transport through an AC-driven impurity: Fano interference and bound states in the continuum

Nonadiabatic Molecular Association in Thermal Gases Driven by Radio-Frequency Pulses

Hydrodynamics with spacetime-dependent scattering length

Contact Info

Product

Resources

About