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Photoassociation of $5snd {}^1{D}_2-5s^2 {}^1{S}_0$ultralong-range Rydberg dimers from an ultracold ${}^{84}\mathrm{Sr}$atomic gas in a magnetic field is studied. In the absence of magnetic fields, the electronic wave function is aligned along the rotating molecular axis through electron-atom scattering. With increasing magnetic field strength, the symmetry axis of the electron wave function becomes determined by the applied field. While the ground-state atom has no spin or net charge to interact directly with the magnetic field, the dimer wave function in the limit of strong magnetic field becomes aligned along the applied field. Photoassociation spectra show that with increasing field, an increasing number of rovibrational states are excited, indicating strong coupling between rotational states within the Rydberg dimer. 

Measurements of the production of $5snd{}^1{D}_2–5s^2{}^1{S}_0$ultralong-range Rydberg dimers through photoassocation in an ultracold ${}^{84}\mathrm{Sr}$atomic gas are reported. The molecular potential associated with the Rydberg $D$state is anisotropic and the molecular states are characterized by the vibrational quantum number $\nu$and the total angular momentum $\vec{K}=\vec{L}+\vec{N}$, where $\vec{L}$and $\vec{N}$are the electronic orbital angular momentum and rotational angular momentum, respectively. The measured molecular binding energies agree reasonably well with theoretical predictions. Additionally, the electron-atom scattering leads to broader line shapes in the photoassociation spectrum than might be expected simply from the angular momentum of the initial colliding cold-atom pairs. 

Chirality in magnetic systems gives rise to a wide range of exotic phenomena, yet its influence in S = 1 chains remains largely unexplored. Here, we present a comprehensive experimental study of a chiral antiferromagnetic (AFM) S = 1 chain, [Ni(pym)(H2O)4]SO4· H2O (pym = pyrimidine), where the Ni(II) octahedral orientation exhibits a four-fold chiral periodicity. Muon spin rotation measurements indicate the onset of long-range magnetic order below TN = 1.82(2) K. Neutron diffraction measurements reveal a chiral AFM order driven by a chiral modulation of the easy-axis anisotropy direction, rather than the typical scenario of Dzyaloshinskii-Moriya interactions, geometrical frustration or higher-order interactions. Inelastic neutron scattering (INS) measurements reveal dispersive spin-wave excitations well described by linear spin-wave theory, with Hamiltonian parameters J0 = 6.81(1)K (intrachain exchange), J′ 1a = −0.091(1)K (interchain exchange), and D = −3.02(1)K (easy-axis single-ion anisotropy). These parameters are further validated by Monte Carlo simulations of the magnetisation. Additionally, the INS data reveal multiple dispersionless bands, suggesting the presence of further excitations beyond the scope of linear spin-wave theory. 

We report measurements of the nonlocal two-body spatial correlation function $g^{\left(2\right)}\left(R\right)$in an ultracold Bose gas with strong interactions using photoassociation of ultra-long-range Rydberg molecules (ULRRMs) as a spatially selective probe. This technique provides access to $g^{\left(2\right)}\left(R\right)$on length scales from 60 to 180 nm, bridging the gap between short-range and long-range correlation measurements. The large $s$-wave scattering length of ${}^{86}\mathrm{Sr}$( $a=811a_0$) enables exploration of the universal regime where $g^{\left(2\right)}\left(R\right)$is governed solely by two-body interactions. Comparison with a weakly interacting isotope, ${}^{84}\mathrm{Sr}$, highlights interaction-induced suppression of pair correlations. The measured correlation functions agree quantitatively with calculations based on the two-body reduced density matrix, without adjustable parameters. Our results establish Rydberg molecular photoassociation as a powerful tool for probing nonlocal correlations in strongly interacting quantum gases. 

The latency and control overhead of sending the preamble in synchronous communications can be excessive when transmitting short sensing/control messages. To reduce these overheads, this work proposes a preamble-free solution based on the framework of quickest change detection. Specific contributions include a joint decoding/demodulation scheme that is provably asymptotically optimal, and a more practical CuSum-like implementation. Numerical results show that the proposed scheme reduces the latency by 47%–79% when compared to the preamble-based solutions. The scheme is also inherently robust and automatically adapts to any unknown underlying SNRs.