Exploring fewbody scattering resonances in a bosefermi. We measured 26 not previously observed resonances, 12 swave and 14 pwave resonances. The rate of association of a boseeinstein condensate bec is of particular inter. The rapid phase change is a general feature of resonance phenomena and the resonant energy dependence of cross sections has been.
They allow us to address key problems in several fields of physics. Analyzing feshbach resonances physikalisches institut. Becbcs crossover with feshbach resonance for three. In recent years, feshbach resonances have been exploited in ultracold col.
However, more generally any autoionizing state generated by removing an innershell electron is a feshbach resonance, and therefore these states underlie auger, costerkronig, or icd decay. It is a feature of manybody systems in which a bound state is achieved if the couplings between at least one internal degree of freedom and the reaction coordinates, which lead to dissociation, vanish. We implement the open and the closed channels inside a pair of such arrays, linked by a separated cavity or a tunable qubit. Thus, an atomic cloud which would not condense in the absence of a magnetic. Quantum mechanical scattering and feshbach resonance. Influence of external magnetic and laser radiation fields.
In addition to two previously known swave resonances, we found three pwave resonances. We show that this resonance phenomenon not only exists during the collisions of massive particles, but also emerges. Observation of broad dwave feshbach resonances with a. Creating ground state molecules with optical feshbach. The bound state perturbs the scattering state which can, in turn, strongly affect the rate of pa 2. Feshbach resonance picture was used to describe nuclear collisions. Feshbachs elegant treatment ofscatteringresonances showedthat scattering phase shifts, and hence cross sections, change rapidly as the collision energy tunes through resonance. Pdf observation of a feshbach resonance in cold atom scattering. Crossover from boseeinstein condensed molecules to. Feshbach resonances, this is not the case for alkalineearth. Feshbach resonance in this context is the interaction of two atoms when, at a particular magnetic b field strength, emmulate a molecule. Dysprosium magnetooptical traps seo ho youn, mingwu lu, ushnish ray, and benjamin l.
Magnetization dynamics for noninteracting particles. With a feshbach resonance the interaction in fermionic quantum gas can be tuned from repulsive to. Near feshbach resonance, a system of two component fermions will form very strongly bound cooper pairs. Inducing an optical feshbach resonance via stimulated. In physics, a feshbach resonance can occur upon collision of two slow atoms, when they temporarily stick together forming an unstable compound with short lifetime socalled resonance. Optical feshbach resonances in a boseeinstein condensate dissertation. The background scattering length is a bg 185a 0, where a 0 is. Lev department of physics, university of illinois at urbanachampaign, urbana, illinois 618080, usa received 9 july 2010. Such a shape resonance occurs when the interatomic. Pdf feshbach resonance induced fano interference in.
Feshbach resonances in cold atomic gases technische. Feshbach resonances and weakly bound molecular states of boson. Box 5, 5600mb eindhoven, the netherlands received 19 june 2002. Inthis chapterwe introducethefeshbachresonances thatare usedtotunethe. Direct observation of resonant scattering phase shifts and.
Photoassociation of a boseeinstein condensate near a. Feshbach resonances in k antje ludewig homepages of uva. Feshbach resonances with large background scattering. Sound propagation in a fermi gas near a feshbach resonance j. In comparison to the wellknown magnetic feshbach resonances, these optical feshbach resonances. February 4, 2008 sound waves are observed and studied in an optically trapped degenerate fermi gas of spinup and spindown atoms with magnetically tunable interactions. Order parameters predicted by lax vector analysis in a 1d system. Observation of an orbital interactioninduced feshbach resonance in 173yb. A feshbach resonance also produces a dramatic change in the scattering length, the parameter that characterizes the interatomic interaction strength within the condensate. Nowadays, probably feshbachs most widely known contribution to physics is the concept known as feshbach resonance. A feshbach resonance occurs when the bound molecularstate in closed channel energetically approaches the scattering state in open channel.
For feshbach molecules, will depend on the magnetic. Feshbach resonance is realized by tuning a molecular bound state near the scattering threshold 1. First described by herman feshbach in a 1958 paper, feshbach resonances describe resonant scattering between two particles when their incoming energies are very close to those of a twoparticle bound state. The first is that for energies away from the resonance, 0. For lindsay leblanc in josephs lab, started september 2007. In addition, in case of onephoton resonance the lower vibrational molecular state is coupled by laser radiation with the continuum of the elastic channel and forms laserinduced feshbach resonance via both autlertownes effect and lics mechanism. Typical lifetimes for excited molecular states are on the order of 10ns which corresponds to a linewidth of 216mhz.
When a single photon is bounded inside the closed channel by setting the relevant physical parameters appropriately, the vanishing transmission appears to. B index to important data files 121 c publications 123 bibliography 7. Note that is project has been superceeded by the feshbachmot coils project. The grosspitaevskii equation for the macroscopically occupied quantum state of each single atom, the condensate wave function.
Two broad resonances from coupling between d waves in both the open and closed channels are observed and characterized. In particular, we observed a wellisolated swave resonance in the. Fanofeshbach resonances in highly magnetic atoms have been observed in chromium. This detuning is related to the heteronuclear scattering length, which is given by a a bg1 w b b 0. Due to the low temperatures of the ultracold gases, their e. Feshbach resonances in lithium6 were experimentally studied and theoretically analyzed. The crucial difference between a shape resonance and a feshbach resonance is that in the latter case, the molecular state responsible for the resonance has a magnetic moment that is different from the magnetic moment of the colliding atoms 17, 183. Similar inelastic collisions occur between clock and target atoms, but because the clock atom density is. Crossover from boseeinstein condensed molecules to cooper pairs by using feshbach resonance shuwei chang department of electrical and computer engineering, university of illinois at urbanachampaign, urbana, il 61801, usa dated. Feshbach resonances with large background scattering length. Feshbachresonances and dissociative electron attachment. A disadvantage of optically induced feshbach resonance is the inherent loss of atoms due to excitation and spontaneous decay of the molecular state 9. A copy of the license is included in the section entitled gnu free documentation license.
As a result, we can tune the binary condensate from being miscible to immiscible simply by varying the magnetic. In this context, magnetic feshbach resonances frs proved to be a. Atomic clock measurements of quantum scattering phase. Duke university, department of physics, durham, north carolina, 27708, usa dated.
In order to obtain a better understanding of the dissociative electron resonance capture processes of h 2 o we have remeasured the ionization efficie the relative intensities of these curves are strongly dependent on the ion focusing conditions. We present a simple onedimensional example of a spin 12 particle submitted to a deltatype potential which interacs differently with the two components of the wavefunction and to an external magnetic field. Observing the creation of electronic feshbach resonances. Feshbach resonances provide an e cient method to producing ultracold molecules. Turning now to fermi systems, one of the major steps in the development of the bcs theory of superconductivity was coopers demonstration in 1956 that a fermi gas. Pdf sound propagation in a fermi gas near a feshbach. Crossing the feshbach resonance, the scattering length a. We consider photoassociation from a state of two free atoms when the continuum state is close to a magnetic field induced feshbach resonance and analyze fano interference in photoassociation. At this frontier of physics, basic questions about the nature of superfluidity, the transition between insulating. It is now also used in many other creative ways to make atomic systems with interactions to order. Feshbach resonances in pwave threebody recombination within fermifermi. Permission is granted to copy, distribute andor modify this document under the terms of the gnu free documentation license, version 1.
In a feshbach resonance, the effective swave scattering length grows when one moves toward the resonance point, and eventually diverges at this point. They have found numerous experimental applications, opening up the way to important breakthroughs. Optical feshbach resonances in a boseeinstein condensate. Feshbach resonance is a resonance for twoatom scattering with two or more channels, in which a bound state is achieved in one channel. Current studies of the bcsbec crossover via feshbach.
Landauzener transitions and a feshbach resonance in. Pairing is a process that is competing with the stoner instability and it would be nice to show that stoner wins in some regimes. Is it that one elastic scattering process is mapped to one bound state. How can one physically understand this phenomenon of feshbach resonance. Observation of an orbital interactioninduced feshbach. Pdf we probe swave collisions of lasercooled 85rb\ f 2,mf 2\ atoms with zeemanresolved photoassociation spectroscopy. Publishers pdf, also known as version of record includes final page. Feshbach resonances in ultracold atoms the budker group. It has two coupled channels, admits a closed solution and features the feshbach resonance phenomenon by proper tunning of the magnetic field. Creating ground state molecules with optical feshbach resonances in tight traps christiane p. Feshbach resonance engineering is a central tool for producing boseeinstein condensates.
Feshbach resonances in fermionic lithium6 request pdf. May 15, 2009 first described by herman feshbach in a 1958 paper, feshbach resonances describe resonant scattering between two particles when their incoming energies. Abm calculated widths of all swave feshbach resonances in stable twocomponent 6li40k mixtures below 500 g. Collisional stability of fermionic feshbach molecules. Feshbach resonances were rst applied to tune the interactions between ultracold fermi gases in the late 1990s. Cold fermions, feshbach resonance, and molecular condensates ii. Although feshbach molecules themselves are extremely \fragile, feshbach resonance association is a potentially coherent method that creates molecules in a sin. May 6, 2004 abstract at low temperature, fermionic atoms can either condense into a boseeinstein condensate bec.
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