Bose-Einstein Condensate Research Articles

Superradiant phononic emission from the analog spin ergoregion in a two-component Bose–Einstein condensate

Superradiant phononic emission from the analog spin ergoregion in a two-component Bose–Einstein condensate

Effects of finite temperature on the magnetized equation of state in neutron stars composed of a Bose-Einstein condensate

Effects of finite temperature on the magnetized equation of state in neutron stars composed of a Bose-Einstein condensate

Spin-driven stationary turbulence in spinor Bose-Einstein condensates

Spin-driven stationary turbulence in spinor Bose-Einstein condensates

Novel resonant multi-soliton solutions of time fractional coupled nonlinear Schrödinger equation in optical fiber via an analytical method

The aim of this article is to investigate the time fractional coupled nonlinear Schrödinger equation (TFCNLSE) which can be used to describe the interaction among the modes in nonlinear optics and Bose–Einstein condensation. The TFCNLS equation plays a crucial role in soliton wavelength division multiplexing and pulse propagation through a two-mode optical fiber. For the sake of getting different analytical solutions, we capitalize modified version of the extended tanh-expansion method. Fractional nonlinear partial differential equations (FNLPDEs) have become popular because they can explain complex physical phenomena and have dynamic structures of localized wave solutions. The study obtained various soliton solutions including bright, dark, periodic, and singular solitons. The results are presented in graphical form with appropriate parameter values to aid visualization. Such solutions are critical for explaining some mesmerizing and complex physical phenomena. In addition, some results from earlier studies are generalized which justify the novelty of the current study. This study proves that the computational method used is efficient, brief, and widely applicable in finding analytical solutions to diverse complex nonlinear problems arising in the recent era of nonlinear optics, applied sciences and engineering.

Effects of quantum fluctuations on macroscopic quantum tunneling and self-trapping of a BEC in a double-well trap

In this paper, we study the influence of quantum fluctuations (QFs) on the macroscopic quantum tunneling and self-trapping (ST) of a two-component Bose–Einstein condensate in a double-well trap. QFs are described by the Lee–Huang–Yang (LHY) term in the modified Gross–Pitaevskii (GP) equation. Employing the modified GP equation in a scalar approximation, we derive a dimer model using a two-mode approximation. The frequencies of Josephson oscillations and ST conditions under QFs are found analytically and proven by numerical simulations of the modified GP equation. The tunneling and localization phenomena are also investigated for the case of the LHY fluid loaded in a double-well potential.

Structure and dynamics of binary Bose–Einstein condensates with vortex phase imprinting

Structure and dynamics of binary Bose–Einstein condensates with vortex phase imprinting

Optimal lattice depth on lifetime of D-band ultracold atoms in a triangular optical lattice.

Ultracold atoms in optical lattices are a flexible and effective platform for quantum precision measurement, and the lifetime of high-band atoms is an essential parameter for the performance of quantum sensors. In this work, we investigate the relationship between the lattice depth and the lifetime of D-band atoms in a triangular optical lattice and show that there is an optimal lattice depth for the maximum lifetime. After loading the Bose-Einstein condensate into D band of optical lattice by shortcut method, we observe the atomic distribution in quasi-momentum space for the different evolution time, and measure the atomic lifetime at D band with different lattice depths. The lifetime is maximized at an optimal lattice depth, where the overlaps between the wave function of D band and other bands (mainly S band) are minimized. Additionally, we discuss the influence of atomic temperature on lifetime. These experimental results are in agreement with our numerical simulations. This work paves the way to improve coherence properties of optical lattices, and contributes to the implications for the development of quantum precision measurement, quantum communication, and quantum computing.

Nonextensive Gross Pitaevskii Equation

In this paper, we consider the generalization of Gross Pitaevskii equation for condensate of bosons with nonextensive statistics. First, we use the non-additive methods and formalism to obtain the well-known Schrödinger equation. Using a suitable Hamiltonian for condensate phase and minimizing the free energy of the system by non-additive formalism, we work out the nonextensive Gross Pitaevskii equation.

Solution of inverse problem for Gross-Pitaevskii equation with artificial neural networks

Abstract We propose an artificial neural network (ANN) design to solve the inverse problem for a 1D Gross–Pitaevskii equation (GPE). More precise, the ANN takes the squared modulus of the stationary GPE solution as an input and returns the parameters of the potential function and the factor in front of the GPE non-linear term. From the physical point of view the ANN predicts the parameters of a trap potential and the interaction constant of 1D Bose–Einstein condensate by its density distribution. Using the results of numerical solution of GPE for more than 30 000 sets of GPE parameters as train and validation datasets we build the ANN as a fast and accurate inverse GPE solver.

Phase Diagram of Dense Two-Color QCD at Low Temperatures

This review is devoted to the modern understanding of the two-color QCD phase diagram at finite baryon density and low temperatures. First, we consider the theoretical picture of this phase diagram. It is believed that at low baryon density, two-color QCD can be described by chiral perturbation theory (ChPT), which predicts a second-order phase transition with Bose-Einstein condensation of diquarks at μ=mπ/2. At larger baryon chemical potentials, the interactions between baryons become important, and ChPT is not applicable anymore. At sufficiently large baryon chemical potential, the Fermi sphere composed of quarks is formed, and diquarks are condensed on the surface of this sphere. In this region, two-color baryon matter reveals properties similar to those of the Quarkyonic phase. Particular attention in this review is paid to lattice studies of dense two-color QCD phase diagram. In the low-density region, the results of lattice studies are in agreement with ChPT predictions. At sufficiently large baryon densities, lattice studies observe a Fermi sphere composed of quarks and condensation of diquarks on its surface. Thus, available lattice studies support most of the theoretical predictions. Finally, we discuss the status of the deconfinement in cold dense two-color matter, which was observed in lattice simulation with staggered fermions.

Stationary modes for vector nonlinear Schrödinger-type equations: A numerical procedure for complete search and its mathematical background

In this paper, we address the problem of complete description of coexisting stationary localized modes for the system of n nonlinearly coupled Schrödinger-type equations. Our approach is based on the observation that if the nonlinearity is defocusing (repulsive), then generic solutions of the corresponding stationary system have singularities at finite points of the real axis and, consequently, cannot describe profiles of stationary modes. Then the stationary localized modes can be found by a procedure of “filtering out” solutions with singularities. We have formulated and proved three rigorous statements that form the mathematical background of the approach. The first of them, Theorem on parametrization, states that there exists a homeomorphism between S and Rn, where S is the set of solutions of the stationary system that decay to zero componentwise at +∞. This allows to code the solutions from S by n-component vectors. The second statement, Theorem on singularity, states that, under certain conditions, the singular solutions are ubiquitous in the system and gives the conditions for detection of singularities. This statement allows to seek for localized modes by properly arranged numerical scanning in S operating with vectors from Rn. The third theorem, Theorem on collapsing solutions, allows to reduce the scanning procedure to a finite domain in Rn. As a result, if the conditions of the three theorems hold, the scanning procedure yields the complete set of localized modes for the system. We illustrate this method by an examples of two and three nonlinearly coupled equations that describe the steady states of two and three- component Bose-Einstein Condensate. As the main outcome, in the chosen domain of chemical potentials, we have found all coexisting nonlinear modes.

Patterning by dynamically unstable spin–orbit-coupled Bose–Einstein condensates

In a two-dimensional atomic Bose–Einstein condensate, we demonstrate Rashba spin–orbit coupling can always introduce dynamical instability into specific zero-quasimomentum states in all parameter regimes. During the evolution of the zero-quasimomentum states, such spin–orbit-coupling-induced instability can fragment the states and lead to a dynamically patterning process. The features of formed patterns are identified from the symmetries of the Bogoliubov–de Gennes Hamiltonian. We show that spin–orbit-coupled Bose–Einstein condensates provide an interesting platform for the investigation of pattern formations.

Pseudo-heterostructure and condensation of 1D moiré excitons in twisted phosphorene bilayers.

Heterostructures are not expected to form in a single homogeneous material. Here, we show that planar pseudo-heterostructures could emerge in a twisted bilayer of phosphorene (tbP), driving in-plane energy and charge transfer. The formation of moiré superlattices combined with electronic anisotropy in tbPs yields one-dimensional (1D) moiré excitons with long radiative and nonradiative lifetimes, large binding energies, and deep moiré potentials. Low-frequency moiré phonons and dynamic moiré potentials are revealed to be responsible for the in-plane energy/charge transfer and exciton dynamics. The 1D moiré excitons are predicted to exhibit Bose-Einstein condensation at high temperatures and may lead to exotic Tonks-Girardeau Bose gases.

Looking for Traces of Nonminimally Coupled Dark Matter in the X-COP Galaxy Clusters Sample

We look for possible evidence of a nonminimal coupling (NMC) between dark matter (DM) and gravity using data from the X-COP compilation of galaxy clusters. We consider a theoretically motivated NMC that may dynamically arise from the collective behavior of the coarse-grained DM field (e.g., via Bose–Einstein condensation) with averaging/coherence length L NMC. In the Newtonian limit, the NMC modifies the Poisson equation by a term proportional to the Laplacian of the DM density itself. We show that this term, when acting as a perturbation over the standard Navarro–Frenk–White (NFW) profile of cold DM particles, can yield DM halo density profiles capable of correctly fitting galaxy clusters’ pressure profiles with an accuracy comparable to and, in some cases, even better than the standard cold DM NFW profile. We also show that the observed relation between the NMC length scale and the virial mass found in Gandolfi et al. for late-type galaxies is consistent with the relation we find in the current work, suggesting that the previously determined power-law scaling law holds up to galaxy cluster mass scales.

Rydberg-dressed Bose–Einstein condensate with spin–orbit coupling confined in a radially periodic potential

The use of Rydberg dressing technology to achieve long-range soft-core interaction in Bose–Einstein condensates (BECs) opens up new avenues for exploration of supersolid and its related phenomenon. We investigate the ground state of a two-component spin–orbit-coupled BECs with both long-range soft-core and contact interactions in radially periodic potentials. Our results show that the ground-state structures of the system are strongly influenced by spin–orbit coupling, contact interactions, long-range soft-core interactions, and the amplitude of the external potential. We find that such parameters can been used to induce desired ground-states structures, such as necklace structure of lump, striped standing wave, and especially ring dark soliton. Furthermore, we observe that the long-range soft-core interactions are used to manipulate the transition between miscible-immiscible phases like contact interactions. Our research provides another degree of freedom for manipulating supersolids in spin–orbit-coupled BECs.

On the spectral gap in the Kac–Luttinger model and Bose–Einstein condensation

We consider the Dirichlet eigenvalues of the Laplacian among a Poissonian cloud of hard spherical obstacles of fixed radius in large boxes of Rd, d≥2. In a large box of side-length 2ℓ centered at the origin, the lowest eigenvalue is known to be typically of order (logℓ)−2/d. We show here that with probability arbitrarily close to 1 as ℓ goes to infinity, the spectral gap stays bigger than σ(logℓ)−(1+2/d), where the small positive number σ depends on how close to 1 one wishes the probability. Incidentally, the scale (logℓ)−(1+2/d) is expected to capture the correct size of the gap. Our result involves the proof of new deconcentration estimates. Combining this lower bound on the spectral gap with the results of Kerner–Pechmann–Spitzer, we infer a type-I generalized Bose–Einstein condensation in probability for a Kac–Luttinger system of non-interacting bosons among Poissonian spherical impurities, with the sole macroscopic occupation of the one-particle ground state when the density exceeds the critical value.

Symmetry-protected Bose-Einstein condensation of interacting hardcore bosons

The large practical potential of exotic quantum states is often precluded by their notorious fragility against external perturbations or temperature. Here, we introduce a mechanism stabilizing a one-dimensional quantum many-body phase exploiting an emergent {{mathbb{Z}}}_{2}-symmetry based on a simple geometrical modification, i.e. a site that couples to all lattice sites. We illustrate this mechanism by constructing the solution of the full quantum many-body problem of hardcore bosons on a wheel geometry, which are known to form Bose-Einstein condensates. The robustness of the condensate against interactions is shown numerically by adding nearest-neighbor interactions, which typically destroy Bose-Einstein condensates. We discuss further applications such as geometrically inducing finite-momentum condensates. Since our solution strategy is based on a generic mapping, our findings are applicable in a broader context, in which a particular state should be protected, by introducing an additional center site.

Bose-Einstein condensation of photons in microcavity plasmas.

Bose-Einstein condensation of a finite number of photons propagating inside a plasma-filled microcavity is investigated. The nonzero chemical potential is provided by the electrons, which induces a finite photon mass and allows condensation to occur. We derive an equationthat models the evolution of the photon-mode occupancies, with Compton scattering taken into account as the mechanism of thermalization. The kinetic evolution of the photon spectrum is solved numerically, and we find evidence of condensation down to nanosecond timescales for typical microplasma conditions, n_{e}∼10^{14}-10^{15}cm^{-3}. The critical temperature scales almost linearly with the number of photons, and we find high condensate fractions at microcavity-plasma temperatures, for experimentally achievable cavity lengths (100-500µm) and photon numbers (10^{10}-10^{12}).

New waves solutions of a nonlinear Landau–Ginzburg–Higgs equation: The Sardar-subequation and energy balance approaches

This article investigates the significance of the unsteady nonlinear Landau–Ginzburg–Higgs equation in the context of superfluids and Bose–Einstein condensates. The problem of interest is the search for new exact solutions within this equation. To tackle this problem, the Sardar-subequation and energy balance approaches are employed. Through these methods, a variety of new exact solutions are obtained, expressed in terms of cosine functions, generalized hyperbolic functions, and generalized trigonometric functions. The obtained solutions encompass different types of solitons, including bright and dark solitons, singular periodic soliton, and hybrid solitons. The solutions are then visualized through 2D and 3D simulations. The findings of this study contribute to the understanding of the Landau–Ginzburg–Higgs equation and its application to superfluids and Bose–Einstein condensates. The novelty of this work lies in the utilization of the Sardar-subequation and energy balance approaches to obtain diverse traveling wave solutions, surpassing previous efforts in the literature.

A unified field theory of topological defects and non-linear local excitations

Topological defects and smooth excitations determine the properties of systems showing collective order. We introduce a generic non-singular field theory that comprehensively describes defects and excitations in systems with O(n) broken rotational symmetry. Within this formalism, we explore fast events, such as defect nucleation/annihilation and dynamical phase transitions where the interplay between topological defects and non-linear excitations is particularly important. To highlight its versatility, we apply this formalism in the context of Bose-Einstein condensates, active nematics, and crystal lattices.