arXiv subjects

Tianmiao Zhang

Publications and source records attributed to Tianmiao Zhang.

3 recordsLinked to original sources

arXiv2026

Formation and dynamics of self-bound droplets in dipolar molecular condensate

We study self-bound quantum droplets in the regime dominated by microwave-induced non-axisymmetric dipole-dipole interactions, using the extended Gross-Pitaevskii equation with the Lee-Huang-Yang corrections. We identify the existence region through numerical simulations and employ an anisotropic Gaussian-super-Gaussian variational ansätz to capture the characteristic density profile of the droplets, with a Gaussian profile along the narrow $x$ direction and super-Gaussian profiles in the extended $(y,z)$ plane. Within this variational framework, we characterize the self-binding, spatial localization, and density-compression properties of the droplets and find good agreement between the variational predictions and the numerical results. Collisions between droplets moving along different directions reveal a strong directional dependence, with outcomes ranging from quasi-elastic rebound and merger to fragmentation. In addition, we explore the rotational dynamics of a single self-bound droplet about all three Cartesian axes, revealing rich and controllable three-dimensional rotational dynamics. Together, these results demonstrate how non-axisymmetric dipolar interactions provide versatile means for controlling the translational, collisional, and rotational dynamics of self-bound quantum droplets.

cond-mat.quant-gas↗

arXiv2026

Pancake-shaped vortex droplets in dipolar molecular BECs

Anisotropic interactions profoundly affect topological excitations in quantum fluids. Motivated by recent advances in the studies of microwave-shielded polar molecules, we introduce self-trapped modes in the form of pancake-shaped quantum droplets (QDs) with embedded vorticity, which are maintained by strongly anisotropic dipole-dipole interactions. The stability region of singly charged ($S=1$) vortices nearly coincides with that of the ground-state QDs ($S=0$), demonstrating the robustness of the vortex states. The strong anisotropy of the system splits the core (pivot) of vortex QDs with $S=2$ into separated unitary ones. The angular momentum and stability of the state with $S=2$ are affected by the separation between the unitary cores. Higher-charge vortex QDs with $S>2$ are stable too, for sufficiently large particle numbers and inter-core separations. On the other hand, bound vortex-antivortex pairs with $S=\pm 1$ are unstable. Head-on collisions between the vortex QDs exhibit distinct regimes, including rebound, merger, and fragmentation. Tuning the cylindrically symmetric component of the dipolar interaction reveals a pronounced sign-dependent response: positive tuning preserves the self-bound vortex, whereas negative tuning drives expansion and fragmentation. The results demonstrate that the microwave-dressed molecular QDs offer a robust platform for the realization of self-trapped vortex states, demonstrating how the strong anisotropy reshapes their structure, stability, and dynamics.

cond-mat.quant-gas↗

arXiv2026

Elastic Modulus in One-Dimensional Quantum Droplets

Quantum droplets (QDs) are self-bound states of ultradilute quantum fluids stabilized by the interplay between the Lee Huang-Yang (LHY) quantum-fluctuation correction and the mean-field interaction, providing a useful platform for exploring macroscopic quantum phenomena. Recent studies on three-dimensional QDs have introduced the concept of bulk modulus and revealed its connection with the breathing-mode frequency, thereby linking the elastic response of QDs to their collective dynamics. Motivated by this progress, we investigate the elastic modulus of one-dimensional QDs. Based on a super Gaussian variational ansatz, we systematically derive the elastic modulus B and analyze its dependence on the interaction strength and particle number. The analytical predictions are further validated by numerical simulations based on imaginary time evolution and the spatial scaling method. We also establish a quantitative relation between the elastic modulus and the eigenfrequency of the breathing mode. In addition, by incorporating corrections to the droplet width beyond the Thomas Fermi approximation, we obtain the dependence of the ratio η = B/2 on the control parameters g and N. Unlike the three-dimensional case, where the corresponding ratio follows a simple power-law scaling, the one-dimensional system is affected by the soliton-to-droplet crossover, leading to a more intricate dependence of η on g and N. Our results show that, in the high-particle-number regime, the elastic modulus asymptotically approaches a limiting value determined mainly by the interaction strength, whereas in the low-particle-number regime it depends on both the particle number and the interaction strength.

cond-mat.quant-gas↗