Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2205.11958

Two rotating particles interacting via two-body Gaussian potential harmonically confined in two spatial dimensions

Md Hamid, M. A. H. Ahsan

Published May 24, 2022• 0 citations
arXivHTMLPDF

Abstract

We study two spinless bosons interacting via two-body Gaussian potential subjected to an externally impressed rotation about an axis confined in a harmonic trap in two-spatial dimensions. We obtain a transcendental equation for the relative angular momentum $|m|$ state with various values of the two-body interaction range $σ$ and the two-body interaction strength $g_{2}$ to study the resulting energy spectrum and analyze the role of Hilbert space dimensions $\widetilde{N}$. We compare results for both attractive and repulsive interaction for $δ$-function potential and Gaussian potential for various values of interaction range. We study the effects of interaction parameters and relative angular momentum on the ground state energy and its various components, namely, kinetic energy, trap potential and interaction potential. For a given $|m|$ and non-interacting case, we observe that the ground state energy becomes independent of interaction range. However, for a given relative angular momentum and interaction strength $g_{2}>0$, there is an increase in ground state energy with an increase in interaction range. Below the interaction strength $g_{2}V(r)\leq -1$, ground state energy diverges to physically unacceptable negative-infinity for $|m|=0$ state. Further, for $|m|=1$, the ground state energy becomes independent of the interaction strength. For a $|m|$, we present a comparative study between the Gaussian interaction potential and the $δ$-function potential. Further, we observe that for a given $g_{2}$ and $|m|$, for $δ$-function potential {\it i.e.} $σ\to 0$, to achieve the convergence of ground state energy, we require a considerably large critical Hilbert space. Whereas, in the case of Gaussian interaction potential with $σ\to 1$, the ground state energy converges for a considerably small critical Hilbert space.

DOI
10.48550/arxiv.2205.11958

Related papers

Two trapped particles interacting by a finite-range two-body potential in two spatial dimensions

Rostislav A. Doganov, Shachar Klaiman, Ofir E. Alon +2 more

We examine the problem of two particles confined in an isotropic harmonic trap, which interact via a finite-range Gaussian-shaped potential in two spatial dimensions. We derive an approximative transcendental equation for the energy and study the resulting spectrum as a function of the interparticle interaction strength. Both the attractive and repulsive systems are analyzed. We study the impact of the potential's range on the ground-state energy. We also explicitly verify by a variational treatment that in the zero-range limit the positive $\ensuremath{\delta}$ potential in two dimensions only reproduces the noninteracting results, if the Hilbert space in not truncated, and demonstrate that an extremely large Hilbert space is required to approach the ground state when one is to tackle the limit of zero-range interaction numerically. Finally, we establish and discuss the connection between our finite-range treatment and regularized zero-range results from the literature. The present results indicate that a finite-range interparticle potential is numerically amenable for treating the statics and the nonequilibrium dynamics of interacting many-particle systems (bosons) in two dimensions.

arXiv:1210.6701•Physical Review A•Mar 28, 2013•46 citations

Ground state properties of trapped boson system with finite-range Gaussian repulsion: exact diagonalization study

Mohd. Imran, M. A. H. Ahsan

Abstract We use exact diagonalization to study an interacting system of N spinless bosons with finite-range Gaussian repulsion, confined in a quasi-two-dimensional harmonic trap with and without an introduced rotation. The diagonalization of the Hamiltonian matrix using Davidson algorithm in subspaces of quantized total angular momentum L z is carried out to obtain the N -body lowest eigenenergy and eigenstate. To bring out the effect of quantum (Bose) statistics and consequent phase stiffness (rigidity) of the variationally obtained many-body wavefunction on various physical quantities, our study spans from few-body ( N = 2) to many-body ( N = 16) systems. Further, to examine the finite-range effect of the repulsive Gaussian potential on many-body ground state properties of the Bose-condensate, we obtain the lowest eigenstate, the critical angular velocity of single vortex state and the quantum correlation (measured) in terms of von Neumann entanglement entropy and degree of condensation. It is found that for small values of the range (measured by the parameter σ ) of Gaussian potential, the ground state energy increases for few-boson (2 ⩽ N ⩽ 8) systems but decreases for many-boson ( N > 8) systems. On the other hand for relatively large values of the range of Gaussian potential, the ground state energy exhibits a monotonic decrease, regardless of the number of bosons N . For a given N , there is found an optimal value of the range of Gaussian potential for which the first vortex (with L z = N ) nucleates at a lower value of the rotational angular velocity Ω c1 compared to the zero-range ( δ -function) potential. Further, we observe that the inter-particle interaction and the introduced rotation are competing effects with latter being dominant over the former. With increase in the range of Gaussian potential, the value of von Neumann entropy decreases and the degree of condensation increases implying an enhanced quantum correlation and phase rigidity.

arXiv:1602.03811•Journal of Physics B Atomic Molecular and Optical Physics•Mar 13, 2020•3 citations

Effects of finite-range Gaussian repulsion on trapped many-boson system

Mohd. Imran, M. A. H. Ahsan

We investigate a rotating system of $N$ spinless bosons confined in quasi-two-dimensional harmonic trap with repulsive finite-range Gaussian interaction potential of large $s$-wave scattering length. Exact diagonalization of the Hamiltonian matrix in subspaces of quantized total angular momenta $L_{z}$ is carried out to obtain the $N$-body ground states in slow rotating regime of $0 \le L_{z} \le 2N$. We study the finite-range effects of the Gaussian repulsion potential on the many-body ground state properties in different subspaces of quantized $L_{z}$. The study ranges from the few-body ($N=2$) system to the many-body ($N=16$), system where quantum (Bose) statistics becomes perceptible. In particular, we analyze the effect of interaction range of the Gaussian potential on the ground state energy of different $L_{z}$ states as well on the critical angular velocity $\Omega_{\bf c1}$ of first vortex ($L_{z}=N$) state. For an optimal value of the range of the Gaussian interaction potential, the nucleation of the first centered vortex may begin at a lower value of the rotational angular velocity as compared to the zero-range interaction potential. Moreover, we explore the role of interaction potential range on the quantum correlation (measured in terms of the degree of condensation and the von Neumann entropy), for small systems ($N=2$ to $8$) where an understanding of few-body effects provide valuable insight into large systems ($N=8$ to $16$) which admit the possibility of many-body correlation. The results obtained indicate that the finite-range Gaussian interaction potential enhances the degree of condensation compared to the zero-range interaction potential.

•Feb 11, 2016•0 citations

Stationary and dynamical properties of two harmonically trapped bosons in the crossover from two dimensions to one

G. Bougas, S. I. Mistakidis, G. M. Alshalan +1 more

We unravel the stationary properties and the interaction quench dynamics of two bosons, confined in a two-dimensional anisotropic harmonic trap. A transcendental equation is derived giving access to the energy spectrum and revealing the dependence of the energy gaps on the anisotropy parameter. The relation between the two- and one-dimensional scattering lengths as well as the Tan contacts is established. The contact, capturing the two-body short-range correlations, shows an increasing tendency for a larger anisotropy. Subsequently, the interaction quench dynamics from attractive to repulsive values and vice versa is investigated for various anisotropies. A closed analytical form of the expansion coefficients of the two-body wave function, during the time evolution is constructed. The response of the system is studied by means of the time-averaged fidelity, the spectra of the spatial extent of the cloud in each direction, and the one-body density. It is found that as the anisotropy increases, the system becomes less perturbed independently of the interactions, while for fixed anisotropy quenches toward the noninteracting regime perturb the system in the most efficient manner. Furthermore, we identify that in the tightly confined direction more frequencies are involved in the dynamics stemming from higher lying excited states.

arXiv:2001.10722•Physical Review A•Jul 15, 2020•14 citations

Exact Diagonalization Study of Bose-Condensed Gas with Finite-Range Gaussian Interaction

Mohd. Imran, M. A. H. Ahsan

We investigate a system of $N$ spinless bosons confined in quasi-two-dimensional harmonic trap with repulsive two-body finite-range Gaussian interaction potential of large $s$-wave scattering length. Exact diagonalization of the Hamiltonian matrix is carried out to obtain the $N$-body ground state as well as low-lying excited states, using Davidson algorithm in beyond lowest-Landau-level approximation. We examine the finite-range effects of the interaction potential on the many-body ground state energy as also the degree of condensation of the Bose-condensed gas. The results obtained indicate that the finite-range Gaussian interaction potential enhances the degree of condensation compared to the zero-range interaction potential. We further analyze the effect of finite-range interaction potential on the breathing mode collective excitation. Our theoretical results may be relevant for experiments currently conducted on quasi-two-dimensional Bose gas with more realistic interaction potential.

arXiv:1511.03165•Advanced Science Letters•Sep 1, 2015•10 citations

Multi-vortex Bose-Einstein condensate: examining the role of interaction range using Gaussian potential

Md Hamid, M. A. H. Ahsan

We present exact diagonalization study on a system of $10 \leq N \leq 24$ spinless bosons interacting via repulsive Gaussian potential, harmonically confined in $xy$-plane with an externally impressed rotation about the $z$-axis. The two-body interaction strength in the Gaussian potential is taken in the strongly interacting regime with values of interaction range in the regime $0\leq σ\leq 1$. The diagonalization of the $N$-body Hamiltonian matrix, in subspaces of total angular momentum in the regime $0\le L_{z} \le 4N$ corresponds to the filling fraction $ν\lesssim 3.2$ is carried out to obtain the variationally exact ground-state wavefunction and the corresponding eigenvalue. It is found that an increase in interaction range $σ$ leads to (a) a systematic decrease in energy, (b) an increase in the critical angular velocity $Ω_{c_{i}}$ of the $i${th} vortex state and (c) an increase in the largest eigenvalue $λ_{1}$, (condensate fraction), of one-particle reduced density matrix (OPRDM). The von Neumann entropy $S_{1}\left(L_{z},σ\right)$, quantifying the quantum entanglement between the particles in the many-body ground state, is largely found to decrease with increase in $σ$. Crossings in von Neumann entropy for several of the angular momentum states are observed with variation in $σ$. The response of the Bose-Einstein condensate to rotation is examined through $L_{z}\left(σ\right)-Ω\left(σ\right)$ stability graph for several values of $σ$. A vortex state with larger plateau length on the $L_{z}-Ω$ graph is considered to be more stable. The internal structure of the condensate, as depicted by the conditional probability distribution (CPD) in the body-fixed frame, exhibits characteristic features with interaction range $σ$. One such feature is the merging of the cores of the two-vortex state.

arXiv:2205.12614•May 25, 2022•0 citations
We study two spinless bosons interacting via two-body Gaussian potential subjected to an externally impressed rotation about an axis confined in a harmonic trap in two-spatial dimensions. We obtain a transcendental equation for the relative angular momentum ∣m∣|m|∣m∣ state with various values of the two-body interaction range σσσ and the two-body interaction strength g2g_{2}g2​ to study the resulting energy spectrum and analyze the role of Hilbert space dimensions N~\widetilde{N}N. We compare results for both attractive and repulsive interaction for δδδ-function potential and Gaussian potential for various values of interaction range. We study the effects of interaction parameters and relative angular momentum on the ground state energy and its various components, namely, kinetic energy, trap potential and interaction potential. For a given ∣m∣|m|∣m∣ and non-interacting case, we observe that the ground state energy becomes independent of interaction range. However, for a given relative angular momentum and interaction strength g2>0g_{2}>0g2​>0, there is an increase in ground state energy with an increase in interaction range. Below the interaction strength g2V(r)≤−1g_{2}V(r)\leq -1g2​V(r)≤−1, ground state energy diverges to physically unacceptable negative-infinity for ∣m∣=0|m|=0∣m∣=0 state. Further, for ∣m∣=1|m|=1∣m∣=1, the ground state energy becomes independent of the interaction strength. For a ∣m∣|m|∣m∣, we present a comparative study between the Gaussian interaction potential and the δδδ-function potential. Further, we observe that for a given g2g_{2}g2​ and ∣m∣|m|∣m∣, for δδδ-function potential {\it i.e.} σ→0σ\to 0σ→0, to achieve the convergence of ground state energy, we require a considerably large critical Hilbert space. Whereas, in the case of Gaussian interaction potential with σ→1σ\to 1σ→1, the ground state energy converges for a considerably small critical Hilbert space.
We examine the problem of two particles confined in an isotropic harmonic trap, which interact via a finite-range Gaussian-shaped potential in two spatial dimensions. We derive an approximative transcendental equation for the energy and study the resulting spectrum as a function of the interparticle interaction strength. Both the attractive and repulsive systems are analyzed. We study the impact of the potential's range on the ground-state energy. We also explicitly verify by a variational treatment that in the zero-range limit the positive $\ensuremath{\delta}$ potential in two dimensions only reproduces the noninteracting results, if the Hilbert space in not truncated, and demonstrate that an extremely large Hilbert space is required to approach the ground state when one is to tackle the limit of zero-range interaction numerically. Finally, we establish and discuss the connection between our finite-range treatment and regularized zero-range results from the literature. The present results indicate that a finite-range interparticle potential is numerically amenable for treating the statics and the nonequilibrium dynamics of interacting many-particle systems (bosons) in two dimensions.
Abstract We use exact diagonalization to study an interacting system of N spinless bosons with finite-range Gaussian repulsion, confined in a quasi-two-dimensional harmonic trap with and without an introduced rotation. The diagonalization of the Hamiltonian matrix using Davidson algorithm in subspaces of quantized total angular momentum L z is carried out to obtain the N -body lowest eigenenergy and eigenstate. To bring out the effect of quantum (Bose) statistics and consequent phase stiffness (rigidity) of the variationally obtained many-body wavefunction on various physical quantities, our study spans from few-body ( N = 2) to many-body ( N = 16) systems. Further, to examine the finite-range effect of the repulsive Gaussian potential on many-body ground state properties of the Bose-condensate, we obtain the lowest eigenstate, the critical angular velocity of single vortex state and the quantum correlation (measured) in terms of von Neumann entanglement entropy and degree of condensation. It is found that for small values of the range (measured by the parameter σ ) of Gaussian potential, the ground state energy increases for few-boson (2 ⩽ N ⩽ 8) systems but decreases for many-boson ( N > 8) systems. On the other hand for relatively large values of the range of Gaussian potential, the ground state energy exhibits a monotonic decrease, regardless of the number of bosons N . For a given N , there is found an optimal value of the range of Gaussian potential for which the first vortex (with L z = N ) nucleates at a lower value of the rotational angular velocity Ω c1 compared to the zero-range ( δ -function) potential. Further, we observe that the inter-particle interaction and the introduced rotation are competing effects with latter being dominant over the former. With increase in the range of Gaussian potential, the value of von Neumann entropy decreases and the degree of condensation increases implying an enhanced quantum correlation and phase rigidity.
We investigate a rotating system of NNN spinless bosons confined in quasi-two-dimensional harmonic trap with repulsive finite-range Gaussian interaction potential of large sss-wave scattering length. Exact diagonalization of the Hamiltonian matrix in subspaces of quantized total angular momenta LzL_{z}Lz​ is carried out to obtain the NNN-body ground states in slow rotating regime of 0≤Lz≤2N0 \le L_{z} \le 2N0≤Lz​≤2N. We study the finite-range effects of the Gaussian repulsion potential on the many-body ground state properties in different subspaces of quantized LzL_{z}Lz​. The study ranges from the few-body (N=2N=2N=2) system to the many-body (N=16N=16N=16), system where quantum (Bose) statistics becomes perceptible. In particular, we analyze the effect of interaction range of the Gaussian potential on the ground state energy of different LzL_{z}Lz​ states as well on the critical angular velocity Ωc1\Omega_{\bf c1}Ωc1​ of first vortex (Lz=NL_{z}=NLz​=N) state. For an optimal value of the range of the Gaussian interaction potential, the nucleation of the first centered vortex may begin at a lower value of the rotational angular velocity as compared to the zero-range interaction potential. Moreover, we explore the role of interaction potential range on the quantum correlation (measured in terms of the degree of condensation and the von Neumann entropy), for small systems (N=2N=2N=2 to 888) where an understanding of few-body effects provide valuable insight into large systems (N=8N=8N=8 to 161616) which admit the possibility of many-body correlation. The results obtained indicate that the finite-range Gaussian interaction potential enhances the degree of condensation compared to the zero-range interaction potential.
We unravel the stationary properties and the interaction quench dynamics of two bosons, confined in a two-dimensional anisotropic harmonic trap. A transcendental equation is derived giving access to the energy spectrum and revealing the dependence of the energy gaps on the anisotropy parameter. The relation between the two- and one-dimensional scattering lengths as well as the Tan contacts is established. The contact, capturing the two-body short-range correlations, shows an increasing tendency for a larger anisotropy. Subsequently, the interaction quench dynamics from attractive to repulsive values and vice versa is investigated for various anisotropies. A closed analytical form of the expansion coefficients of the two-body wave function, during the time evolution is constructed. The response of the system is studied by means of the time-averaged fidelity, the spectra of the spatial extent of the cloud in each direction, and the one-body density. It is found that as the anisotropy increases, the system becomes less perturbed independently of the interactions, while for fixed anisotropy quenches toward the noninteracting regime perturb the system in the most efficient manner. Furthermore, we identify that in the tightly confined direction more frequencies are involved in the dynamics stemming from higher lying excited states.
We investigate a system of NNN spinless bosons confined in quasi-two-dimensional harmonic trap with repulsive two-body finite-range Gaussian interaction potential of large sss-wave scattering length. Exact diagonalization of the Hamiltonian matrix is carried out to obtain the NNN-body ground state as well as low-lying excited states, using Davidson algorithm in beyond lowest-Landau-level approximation. We examine the finite-range effects of the interaction potential on the many-body ground state energy as also the degree of condensation of the Bose-condensed gas. The results obtained indicate that the finite-range Gaussian interaction potential enhances the degree of condensation compared to the zero-range interaction potential. We further analyze the effect of finite-range interaction potential on the breathing mode collective excitation. Our theoretical results may be relevant for experiments currently conducted on quasi-two-dimensional Bose gas with more realistic interaction potential.
We present exact diagonalization study on a system of 10≤N≤2410 \leq N \leq 2410≤N≤24 spinless bosons interacting via repulsive Gaussian potential, harmonically confined in xyxyxy-plane with an externally impressed rotation about the zzz-axis. The two-body interaction strength in the Gaussian potential is taken in the strongly interacting regime with values of interaction range in the regime 0≤σ≤10\leq σ\leq 10≤σ≤1. The diagonalization of the NNN-body Hamiltonian matrix, in subspaces of total angular momentum in the regime 0≤Lz≤4N0\le L_{z} \le 4N0≤Lz​≤4N corresponds to the filling fraction ν≲3.2ν\lesssim 3.2ν≲3.2 is carried out to obtain the variationally exact ground-state wavefunction and the corresponding eigenvalue. It is found that an increase in interaction range σσσ leads to (a) a systematic decrease in energy, (b) an increase in the critical angular velocity ΩciΩ_{c_{i}}Ωci​​ of the iii{th} vortex state and (c) an increase in the largest eigenvalue λ1λ_{1}λ1​, (condensate fraction), of one-particle reduced density matrix (OPRDM). The von Neumann entropy S1(Lz,σ)S_{1}\left(L_{z},σ\right)S1​(Lz​,σ), quantifying the quantum entanglement between the particles in the many-body ground state, is largely found to decrease with increase in σσσ. Crossings in von Neumann entropy for several of the angular momentum states are observed with variation in σσσ. The response of the Bose-Einstein condensate to rotation is examined through Lz(σ)−Ω(σ)L_{z}\left(σ\right)-Ω\left(σ\right)Lz​(σ)−Ω(σ) stability graph for several values of σσσ. A vortex state with larger plateau length on the Lz−ΩL_{z}-ΩLz​−Ω graph is considered to be more stable. The internal structure of the condensate, as depicted by the conditional probability distribution (CPD) in the body-fixed frame, exhibits characteristic features with interaction range σσσ. One such feature is the merging of the cores of the two-vortex state.