Ultracold Dense Samples of Dipolar RbCs Molecules in the Rovibrational and Hyperfine Ground State

The field of ultracold quantum matter has burgeoned over the last few decades, thanks to the growing capabilities for atomic systems to be probed and manipulated with exquisite control. Researchers can now precisely create and study quantum manybody states that are effectively isolated from the external environment. Much of the work in ultracold matter has focused on systems of alkali or alkaline-earth atoms, mainly due to their ease of cooling. Extending this precise control to molecules has seen rapidly increasing interest and activity, as molecules possess additional degrees of freedom that make them useful for tests of fundamental physics, studying ultracold chemistry and collisions, and engineering qualitatively new types of quantum phases and quantum many-body systems. Here, we review one particularly fruitful research direction: the creation and manipulation of ultracold bialkali molecules. The recent success in creating a quantum gas of polar molecules opens many exciting research opportunities. Atomic, Molecular, and Optical (AMO) systems offer experimentalists the ability to precisely control interactions in a quantum many-body system [1,2], and a rich set of experiments has already been performed. Some prominent examples include studies of the BEC-BCS crossover in two-component Fermi gases [3,4,5] and the superfluid-Mott insulator transition in ultracold bosons loaded into a 3D optical lattice [6]. Neutral atomic systems normally have point-like contact interactions that can be parametrized with a single quantity, the scattering length a, which can be tuned via a Feshbach resonance [2]. In recent years, systems with long-range and anisotropic interactions have garnered much attention. One natural example is the dipolar interaction between polar molecules, which is the focus of this Review. Of course, many other experimental platforms are also being pursued that feature long-range interactions, including highly magnetic atoms [7,8], trapped ions The dipolar interaction exhibits several important attributes. First, the energy scales in dipolar systems are usually much larger than those in typical atomic alkali systems, making it easier to study interaction-driven structural properties and non-equilibrium dynamics. Second, and perhaps more importantly, the anisotropic and long-range nature of the interaction allows for the realization of novel quantum phases, especially when the spatial dimensions of the system can be varied with optical lattices. Some of these engineered systems may find relevance to outstanding problems in condensed-matter physics [13,14]; moreover, qualitatively new types of physics can emerge in the presence of long-range interactions [15,16,17,18,19,20,21]. As a specific example of a unique feature of long-range interactions, a spin-1/2 Hamiltonian can be encoded based on a pair of oppositeparity rotational states where dipolar interactions give rise to a direct spin exchange coupling between molecules [22,23]. With this scheme implemented in an optical lattice, many-body spin dynam...

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“…Preliminary experiments with RbCs [38] and NaRb [41] suggest this may actually occur (Fig. 3f), although more work is needed to confirm this.…”

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confidence: 98%

New frontiers for quantum gases of polar molecules

et al. 2016

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“…The hyperfine Hamiltonian (3) consists of four terms. The first is the interaction between the nuclear electric quadrupole tensor Q and the electric-field gradient V due to the electrons, which is characterized by coupling constants (eQq) 1 and (eQq) 2 . The second is the interaction between the nuclear magnetic moments and the magnetic field created by the rotation of the molecule, with spin-rotation coupling constants c 1 and c 2 .…”

Section: Molecular Hamiltonianmentioning

confidence: 99%

“…The polar molecules produced so far include 40 K 87 Rb [1], 87 Rb 133 Cs [2,3], 23 Na 40 K [4], and 23 Na 87 Rb [5]. Such molecules have many potential applications, ranging from quantum-statecontrolled chemistry [6][7][8][9] to quantum simulation [10,11] and quantum information [12,13].…”

Section: Introductionmentioning

confidence: 99%

Hyperfine structure of alkali-metal diatomic molecules

Aldegunde

Hutson

2017

Phys. Rev. A

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We present calculations of the hyperfine coupling constants for all the heteronuclear alkali-metal diatomic molecules at the equilibrium geometry of the electronic ground state. These constants are important in developing methods to control ultracold polar molecules. The results are based on electronic structure calculations using density functional theory, and are in good agreement with experiment for the limited set of molecules for which experiments are so far available

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“…Such mixtures have been used to study Efimov physics [13][14][15], probe impurities in Bose gases [16], and entropically cool gases confined in an optical lattice [17]. Pairs of atoms in the mixtures can be combined using magnetically or optically tunable Feshbach resonances to create ultracold molecules [18][19][20][21][22][23][24][25][26]. These ultracold molecules have a wealth of applications, such as tests of fundamental physics [27][28][29], realization of novel phase transitions [30][31][32], and the study of ultracold chemistry [33,34].…”

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Interspecies thermalization in an ultracold mixture of Cs and Yb in an optical trap

et al. 2017

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We present measurements of interspecies thermalization between ultracold samples of 133 Cs and either 174 Yb or 170 Yb. The two species are trapped in a far-off-resonance optical dipole trap and 133 Cs is sympathetically cooled by Yb. We extract effective interspecies thermalization cross sections by fitting the thermalization measurements to a kinetic model, giving σ Cs 174 Yb = (5 ± 2) × 10 −13 cm 2 and σ Cs 170 Yb = (18 ± 8) × 10 −13 cm 2 . We perform quantum scattering calculations of the thermalization cross sections and optimize the CsYb interaction potential to reproduce the measurements. We predict scattering lengths for all isotopic combinations of Cs and Yb. We also demonstrate the independent production of 174 Yb and 133 Cs Bose-Einstein condensates using the same optical dipole trap, an important step towards the realization of a quantum-degenerate mixture of the two species.The realization of ultracold atomic mixtures [1][2][3][4][5][6][7][8][9][10][11][12] has opened up the possibility of exploring new regimes of few-and many-body physics. Such mixtures have been used to study Efimov physics [13][14][15], probe impurities in Bose gases [16], and entropically cool gases confined in an optical lattice [17]. Pairs of atoms in the mixtures can be combined using magnetically or optically tunable Feshbach resonances to create ultracold molecules [18][19][20][21][22][23][24][25][26]. These ultracold molecules have a wealth of applications, such as tests of fundamental physics [27][28][29], realization of novel phase transitions [30][31][32], and the study of ultracold chemistry [33,34]. In addition, the long-range dipole-dipole interactions present between pairs of polar molecules make them useful in the study of dipolar quantum matter [35,36] and ultracold molecules confined in an optical lattice can simulate a variety of condensedmatter systems [37][38][39].Although the large majority of work on ultracold molecules has focused on bi-alkali systems, there is burgeoning interest in pairing alkali-metal atoms with divalent atoms such as Yb [40][41][42][43][44][45] or Sr [46]. The heteronuclear 2 Σ molecules formed in these systems have both an electric and a magnetic dipole moment in the ground electronic state. The extra magnetic degree of freedom opens up new possibilities for simulating a range of Hamiltonians for spins interacting on a lattice and for topologically protected quantum information processing [47].One of the challenging aspects of creating molecules in these systems is that the Feshbach resonances tend to be narrow and sparse. They are narrow because the main coupling responsible for them is the weak distance dependence of the alkali-metal hyperfine coupling, caused by the spin-singlet atom at short range [48] [48,49], and for some systems may be at impractically high magnetic fields. Amongst the various alkali-Yb combinations, CsYb has been proposed as the most favorable candidate because the high mass of Cs facilitates a higher density of bound states near threshold and its large hyperfi...

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Ultracold Dense Samples of Dipolar RbCs Molecules in the Rovibrational and Hyperfine Ground State

Cited by 552 publications

References 33 publications

New frontiers for quantum gases of polar molecules

New frontiers for quantum gases of polar molecules

Hyperfine structure of alkali-metal diatomic molecules

Interspecies thermalization in an ultracold mixture of Cs and Yb in an optical trap

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