arXiv subjects

Ritu

Publications and source records attributed to Ritu.

4 recordsLinked to original sources

arXiv2026

Metastability, collective excitations, and traveling states of one-dimensional spin-orbit-coupled quantum droplets

We study the static and traveling droplet phases of spin-orbit coupled, one-dimensional Bose-Bose mixtures with a Lee-Huang-Yang correction. For the static droplets, employing a variational analysis for an infinitely extended mixture, we show that the system can feature two ground-state droplet phases: a stripe droplet phase up to a critical Rabi coupling strength, at which it undergoes a first-order transition to a zero-momentum droplet phase. The variational results for the ground-state properties are shown to be in good agreement with numerical solutions for droplets in the thermodynamic limit as well as finite-size droplets in the "flat-top regime". For finite-size droplets, the stripe phase can feature multiple stationary states with different numbers of peaks in their stripe density patterns. The calculation of the excitation spectrum for these stationary states confirms their stability. To study the moving droplets, we investigate the ground-state phases of the system in the droplet's comoving frame. We show that in the comoving frame, droplets acquire a finite longitudinal magnetization. As a consequence, the phase diagram features two distinct phases: a traveling stripe droplet and a plane-wave droplet. The real-time evolution of these droplets in the space-fixed frame, complemented by the Bogoliubov analysis in the comoving frame, illustrates the stability of these traveling droplet phases.

cond-mat.quant-gas↗

arXiv2026

Spin and density excitations of one-dimensional self-bound Bose-Bose droplets

We study spin and density excitations of one-dimensional self-bound Bose-Bose droplets within Bogoliubov theory, and show that spin excitations come alive, especially as the interspecies coupling is made less attractive. We argue that spin excitations are particularly relevant in the one-dimensional droplet regime, where droplets are realized within the mean-field stability regime, as has been confirmed by the quantum Monte Carlo simulations. As the interspecies coupling strength increases within the mean-field stability regime, spin modes ultimately fall below the particle-emission threshold, thus becoming observable in the droplet spectrum. We analyze the Bogoliubov model for both pseudospinor and population-imbalanced scalar mixtures, encompassing both the density and spin sectors. We corroborate our findings through variational analysis of density- and spin-breathing modes, which offers physical insight into the mode structure and independently validates the spectrum, as well as through real-time dynamics. Additionally, we compare our results with both Petrov's original theory, which considers the Lee-Huang-Yang (LHY) correction at the attractive edge of the mean-field stability regime, and a beyond-LHY description of Bose-Bose mixtures.

cond-mat.quant-gas↗

arXiv2024

Thermal amplification and melting of phases in spin-orbit-coupled spin-1 Bose-Einstein condensates

We implement Hartree-Fock-Bogoliubov theory with Popov approximation for a homogeneous Raman-induced spin-orbit-coupled spin-1 Bose-Einstein condensate and investigate the effects of finite temperature ($T$) on the ground-state phase diagram. We calculate the roton gap as a function of Raman coupling ($Ω$) or quadratic Zeeman field strength ($ε$) to extract the critical points separating the supersolid stripe phase from the plane wave or zero-momentum phase at finite temperatures. We present a few representative finite-temperature phase diagrams for the system in the $T-Ω$ and $T-ε$ planes. Our observations indicate that the supersolid stripe phase melts at finite temperatures. We also discuss the contrasting roles of quantum and thermal fluctuations in shifting the phase boundary separating the supersolid stripe from the plane-wave phase.

cond-mat.quant-gas↗

arXiv2024

Temperature-induced supersolidity in spin-orbit-coupled Bose gases

Close to the superfluid plane-wave (PW) - supersolid stripe (ST) phase transition point of a zero temperature quasi-one-dimensional spin-orbit-coupled Bose gas, we find that an increase in temperature induces a phase transition to the supersolid phase with a broken translational symmetry from the superfluid plane-wave phase. We use the Hartree-Fock-Bogoliubov theory with the Popov approximation to investigate the effect of thermal fluctuations on the collective excitation spectrum and investigate the softening of the spin-dipole mode corresponding to the shift in the quantum critical point. This is in stark contrast to the PW-ST phase transition in a homogeneous system where non-zero temperatures facilitate the melting of the stripe phase.

cond-mat.quant-gas↗