arXiv subjects

Philipp Stürmer

Publications and source records attributed to Philipp Stürmer.

5 recordsLinked to original sources

arXiv2026

Vorticity-Crystalline Order Coupling in Supersolids: Excitations and Re-entrant Phases

Rotation is a natural tool in ultracold gases to break time-reversal symmetry, yet its impact on the collective excitations of supersolids remains largely unexplored. We show theoretically that tuning the rotation frequency, rather than the interparticle interactions, can trigger the superfluid-to-supersolid transition in Bose-Einstein condensates (dBECs). Computing excitation spectra in the presence of vortices and persistent currents, we uncover a vortex-driven de-softening mechanism whereby quantized vorticity elevates the gapless Goldstone mode to a finite-energy roton, restoring superfluidity. This effect results in re-entrant supersolid phases as a function of rotation frequency, revealing a fundamental coupling between topological defects and crystalline order.

cond-mat.quant-gas↗

arXiv2024

Decoupled sound and amplitude modes in trapped dipolar supersolids

We theoretically investigate elementary excitations of dipolar quantum gases across the superfluid to supersolid phase transition in a toroidal trap. We show how decoupled first sound, second sound, and Higgs modes emerge by following their origin from superfluid modes across the transition. The structure of these excitations reveals the interplay between crystal and superfluid oscillations. Our results unify previous notions of coupled Goldstone and Higgs modes in harmonic traps, allowing us to establish a correspondence between excitations of trapped and infinitely extended supersolids. We propose protocols for selectively probing these sound and amplitude modes, accessible to state-of-the-art experiments.

cond-mat.quant-gas↗

arXiv2023

Toroidal Dipolar Supersolid with a Rotating Weak Link

Ring-shaped superfluids with weak links provide a perfect environment for studying persistent currents and dynamic stirring protocols. Here, we investigate the effects of a weak-link system on dipolar supersolids. By calculating the ground state energy at fixed angular momenta, we find that metastable persistent currents may exist in the supersolid phase near the superfluid transition point. When stirring the weak link rapidly enough, we show that vortices can enter the supersolid. These vortex entries cause phase slips, emitting solitonic excitations that interfere with the crystalline structure of the supersolid, leading to a continuous melting and recrystallization of the droplets. Finally, we examine the release of vortex-carrying supersolids from the trap, observing that the released density exhibits a discrete structure associated with the density modulation and a central hole resulting from the vortex core.

cond-mat.quant-gas↗

arXiv2022

Mixed Bubbles in a one-dimensional Bose-Bose mixture

We investigate a Bose-Bose mixture across the miscible-immiscible phase transition governed by quantum fluctuations in one dimension. We find the recently predicted so-called mixed bubbles as ground states close to the mean-field miscible-immiscible threshold. These bubbles form a pocket of miscibility, separated by one of the components. The collective excitations reflect the symmetry breaking resulting from the bubble formation. The partial miscibility of the system allows for persistent currents in an annular confinement. Intriguingly, the mixed bubble acts like an intrinsic weak link, connecting the rotational behavior of the mixed bubble state to current efforts in atomtronic applications.

cond-mat.quant-gas↗

arXiv2020

Breathing mode in two-dimensional binary self-bound Bose gas droplets

In this work, we present the study of the stationary structures and the breathing mode behavior of a two-dimensional self-bound binary Bose droplet. We employ an analytical approach using a variational ansatz with a super-Gaussian trial order parameter and compare it with the numerical solutions of the extended Gross-Pitaevskii equation. We find that the super-Gaussian is superior to the often used Gaussian ansatz in describing the stationary and dynamical properties of the system. We find that for sufficiently large non-rotating droplets the breathing mode is energetically favourable compared to the self-evaporating process. For small self-bound systems our results differ based on the ansatz. Inducing angular momentum by imprinting multiply quantized vortices at the droplet center, this preference for the breathing mode persists independent of the norm.

cond-mat.quant-gas↗