We produce ultracold dense trapped samples of ^{87}Rb^{133}Cs molecules in their rovibrational ground state, with full nuclear hyperfine state control, by stimulated Raman adiabatic passage (STIRAP) efficiencies 90%. observe the onset hyperfine-changing collisions when magnetic field is ramped so that are no longer state. A strong quadratic shift transition frequencies as a function applied electric shows strongly dipolar character RbCs ground-state molecule. Our results open up prospect...

Ultracold polar molecules offer strong electric dipole moments and rich internal structure, which makes them ideal building blocks to explore exotic quantum matter

Abstract The interplay of quantum statistics and interactions in atomic Bose–Fermi mixtures leads to a phase diagram markedly different from pure fermionic or bosonic systems. However, investigating this remains challenging when bosons condense due the resulting fast interspecies loss. Here we report observations consistent with transition polaronic molecular density-matched degenerate mixture. condensate fraction, representing order parameter transition, is depleted by interactions,...

Understanding collisions between ultracold molecules is crucial for making stable molecular quantum gases and harnessing their rich internal degrees of freedom engineering. Transient complexes can strongly influence collisional physics, but in the regime, key aspects behavior have remained unknown. To explain experimentally observed loss ground-state from optical dipole traps, it was recently proposed that be lost due to photoexcitation. By trapping a repulsive box potential using laser...

Collisional complexes, which are formed as intermediate states in molecular collisions, typically short-lived and decay within picoseconds. However, ultracold collisions involving bialkali molecules, complexes can live for milliseconds, completely changing the collision dynamics. This lead to unexpected two-body loss samples of nonreactive molecules. During past decade, such "sticky" have been a major hindrance preparation dense stable samples, especially quantum-degenerate regime....

Abstract Scattering resonances are an essential tool for controlling the interactions of ultracold atoms and molecules. However, conventional Feshbach scattering 1 , which have been extensively studied in various platforms 1–7 not expected to exist most polar molecules because fast loss that occurs when two approach at a close distance 8–10 . Here we demonstrate new type resonance is universal wide range The so-called field-linked 11–14 occur microwave-dressed stable macroscopic tetramer...

We demonstrate coherent control of the fine-structure qubit in neutral strontium atoms. This is encoded metastable <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mmultiscripts><a:mrow><a:msub><a:mrow><a:mi>P</a:mi></a:mrow><a:mrow><a:mn>2</a:mn></a:mrow></a:msub></a:mrow><a:mprescripts/><a:none/><a:mrow><a:mn>3</a:mn></a:mrow></a:mmultiscripts></a:mrow></a:math> and <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"...

We demonstrate a generally applicable technique for mixing two-species quantum degenerate bosonic samples in the presence of an optical lattice, and we employ it to produce low-entropy ultracold ^{87}Rb^{133}Cs Feshbach molecules with lattice filling fraction exceeding 30%. Starting from two spatially separated Bose-Einstein condensates Rb Cs atoms, Rb-Cs atom pairs are efficiently produced by using superfluid-to-Mott insulator phase transition twice, first sample, then after nulling...

We demonstrate a versatile, state-dependent trapping scheme for the ground and first excited rotational states of $^{23}\mathrm{Na}^{40}\mathrm{K}$ molecules. Close to manifold narrow electronic transition, we determine tune-out frequencies where polarizability one state vanishes while other remains finite, magic frequency both experience equal polarizability. The proximity these only 10 GHz allows dynamic switching between different trap configurations in single experiment, still...

We demonstrate the transfer of $^{23}\mathrm{Na}^{40}\mathrm{K}$ molecules from a closed-channel-dominated Feshbach-molecule state to absolute ground state. The Feshbach are initially created gas sodium and potassium atoms via adiabatic ramping over resonance at 78.3 G. then transferred using stimulated Raman passage with an intermediate in spin-orbit-coupled complex...

We study three-body loss in an ultracold mixture of a thermal Bose gas and degenerate Fermi gas. find that at unitarity, where the interspecies scattering length diverges, usual inverse-square temperature scaling found nondegenerate systems is strongly modified reduced with increasing degeneracy While reduction qualitatively explained within few-body framework, remaining suppression provides evidence for long-range Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions mediated by fermions...

Ultracold fermionic Feshbach molecules are promising candidates for exploring quantum matter with strong $p$-wave interactions; however, their lifetimes were measured to be short. Here we characterize the collisions of ultracold $^{23}\mathrm{Na}^{40}\mathrm{K}$ different scattering lengths and temperatures. By increasing binding energy molecules, two-body loss coefficient reduces by three orders magnitude, leading a second-long lifetime 20 times longer than that ground-state NaK molecules....

We report on the observation of confinement-induced resonances for strong three-dimensional (3D) confinement in a lattice potential. Starting from Mott-insulator state with predominantly single-site occupancy, we detect loss and heating features at specific values length 3D scattering length. Two independent models, based coupling between center-of-mass relative motion particles as mediated by lattice, predict resonance positions to good approximation, suggesting universal behavior. Our...

Ultracold polyatomic molecules offer intriguing new opportunities in cold chemistry, precision measurements, and quantum information processing, thanks to their rich internal structure. However, increased complexity compared diatomic presents a formidable challenge employ conventional cooling techniques. Here, we demonstrate approach create ultracold by electroassociation degenerate Fermi gas of microwave-dressed polar through field-linked resonance. Starting from ground state NaK molecules,...

We demonstrate coherent control of the fine-structure qubit in neutral strontium atoms. This is encoded metastable $^3\mathrm{P}_2$ and $^3\mathrm{P}_0$ states, coupled by a Raman transition. Using magnetic quadrupole transition, we state-initialization this THz qubit. show Rabi oscillations with more than 60 cycles single-qubit rotations on $\mu$s scale. With spin-echo, coherence times tens ms. Our results pave way for fast quantum information processors highly tunable simulators two-electron

The interplay of quantum statistics and interactions in atomic Bose--Fermi mixtures leads to a phase diagram markedly different from pure fermionic or bosonic systems. However, investigating this remains challenging when bosons condense. Here, we observe evidence for transition polaronic molecular density-matched degenerate mixture. condensate fraction, representing the order parameter transition, is depleted by build-up strong correlations results emergence Fermi gas. By driving through...

Abstract Ultracold polyatomic molecules offer intriguing new opportunities [1] in cold chemistry [2, 3], precision measurements [4], and quantum information processing [5, 6], thanks to their rich internal structure. However, increased complexity compared diatomic presents a formidable challenge employ conventional cooling techniques. Here, we demonstrate approach create ultracold by electroassociation [7, 8] degenerate Fermi gas of microwave-dressed polar through field-linked resonance...

Ultracold polar molecules offer strong electric dipole moments and rich internal structure, which makes them ideal building blocks to explore exotic quantum matter, implement novel information schemes, or test fundamental symmetries of nature. Realizing their full potential requires cooling interacting molecular gases deeply into the degenerate regime. However, complexity collisions intrinsically unstable at short range, even for nonreactive molecules, has so far prevented degeneracy in...

Ultracold fermionic Feshbach molecules are promising candidates for exploring quantum matter with strong $p$-wave interactions, however, their lifetimes were measured to be short. Here, we characterize the collisions of ultracold $^{23}\mathrm{Na}^{40}\mathrm{K}$ different scattering lengths and temperatures. By increasing binding energy molecules, two-body loss coefficient reduces by three orders magnitude leading a second-long lifetime, 20 times longer than that ground-state molecules. We...

Scattering resonances are an essential tool for controlling interactions of ultracold atoms and molecules. However, conventional Feshbach scattering resonances, which have been extensively studied in various platforms, not expected to exist most polar molecules due the fast loss that occurs when two approach at a close distance. Here, we demonstrate new type is universal wide range The so-called field-linked occur microwave-dressed stable macroscopic tetramer states intermolecular potential....