Abstract
We consider the Bohmian trajectories in a 2-d quantum harmonic oscillator with non commensurable frequencies whose wavefunction is of the form \(\Psi =a\Psi _{m_1,n_1}(x,y)+b\Psi _{m_2,n_2}(x,y)+c\Psi _{m_3,n_3}(x,y)\). We first find the trajectories of the nodal points for different combinations of the quantum numbers m, n. Then we study, in detail, a case with relatively large quantum numbers and two equal \(m's\). We find (1) fixed nodes independent of time and (2) moving nodes which from time to time collide with the fixed nodes and at particular times they go to infinity. Finally, we study the trajectories of quantum particles close to the nodal points and observe, for the first time, how chaos is generated in a complex system with multiple nodes scattered on the configuration space.
Similar content being viewed by others
Data Availability
The datasets generated during the current study are available from the corresponding author on reasonable request.
Notes
In fact we have
$$\begin{aligned} \Psi _{m,n}=\Psi _m(x)\cdot \Psi _n(y), \end{aligned}$$(8)where
$$\begin{aligned} \Psi _l(x)=\frac{1}{\sqrt{2^ll!}}\left( \frac{m_x\omega _x}{\pi \hbar }\right) ^{\frac{1}{4}}e^{-\frac{m_x\omega _x x^2}{2\hbar }}H_l\left( \sqrt{\frac{m_x\omega _ x}{\hbar }}x\right) ,l=0, 1, 2,\dots , \end{aligned}$$(9)and similarly for y.
This is an example of a non stationary state with stationary nodes and chaos. This answers a question raised by Cesa, Martin and Struyve [26], who could not find a system of this type and wondered if such a system would generate chaos.
References
Bohm, D.: A suggested interpretation of the quantum theory in terms of hidden variables. I. Phys. Rev. 85, 166 (1952)
Bohm, D.: A suggested interpretation of the quantum theory in terms of “hidden" variables. II. Phys. Rev. 85, 180 (1952)
Holland, P.R.: The Quantum Theory of Motion: An Account of the de Broglie-Bohm Causal Interpretation of Quantum Mechanics. Cambridge University Press, Cambridge (1995)
Parmenter, R.H., Valentine, R.: Deterministic chaos and the causal interpretation of quantum mechanics. Phys. Lett. A 201, 1 (1995)
Iacomelli, G., Pettini, M.: Regular and chaotic quantum motions. Phys. Lett. A 212, 29 (1996)
Sengupta, S., Chattaraj, P.: The quantum theory of motion and signatures of chaos in the quantum behaviour of a classically chaotic system. Phys. Lett. A 215, 119 (1996)
de Sales, J., Florencio, J.: Quantum chaotic trajectories in integrable right triangular billiards. Phys. Rev. E 67, 016216 (2003)
Efthymiopoulos, C., Contopoulos, G.: Chaos in Bohmian quantum mechanics. J. Phys. A 39, 1819 (2006)
Contopoulos, G., Tzemos, A.C.: Chaos in Bohmian quantum mechanics: a short review. Regul. Chaotic Dyn. 25, 476 (2020)
Efthymiopoulos, C., Kalapotharakos, C., Contopoulos, G.: Nodal points and the transition from ordered to chaotic Bohmian trajectories. J. Phys. A 40, 12945 (2007)
Efthymiopoulos, C., Kalapotharakos, C., Contopoulos, G.: Origin of chaos near critical points of quantum flow. Phys. Rev. E 79, 036203 (2009)
Benseny, A., Albareda, G., Sanz, Á.S., Mompart, J., Oriols, X.: Applied Bohmian mechanics. Eur. Phys. J. D 68, 1 (2014)
Frisk, H.: Properties of the trajectories in Bohmian mechanics. Phys. Lett. A 227, 139 (1997)
Konkel, S., Makowski, A.: Regular and chaotic causal trajectories for the Bohm potential in a restricted space. Phys. Lett. A 238, 95 (1998)
Wu, H., Sprung, D.: Quantum chaos in terms of Bohm trajectories. Phys. Lett. A 261, 150 (1999)
Barker, J., Akis, R., Ferry, D.: On the use of Bohm trajectories for interpreting quantum flows in quantum dot structures. Superlattices Microstruct. 27, 319 (2000)
Falsaperla, P., Fonte, G.: On the motion of a single particle near a nodal line in the de Broglie–Bohm interpretation of quantum mechanics. Phys. Lett. A 316, 382 (2003)
Wisniacki, D., Borondo, F., Benito, R.: Dynamics of quantum trajectories in chaotic systems. Europhys. Lett. 64, 441 (2003)
Sanz, A., Borondo, F., Miret-Artés, S.: Quantum trajectories in atom-surface scattering with single adsorbates: the role of quantum vortices. J. Chem. Phys. 120, 8794 (2004)
Sanz, A., Borondo, F., Miret-Artés, S.: Role of quantum vortices in atomic scattering from single adsorbates. Phys. Rev. B 69, 115413 (2004)
Wisniacki, D.A., Pujals, E.R.: Motion of vortices implies chaos in Bohmian mechanics. Europhys. Lett. 71, 159 (2005)
Wisniacki, D., Pujals, E., Borondo, F.: Vortex dynamics and their interactions in quantum trajectories. J. Phys. A 40, 14353 (2007)
Chou, C.-C., Wyatt, R.E.: Quantum vortices within the complex quantum Hamilton–Jacobi formalism. J. Chem. Phys. 128, 234106 (2008)
Sanz, A., Miret-Artés, S.: Interplay of causticity and vorticality within the complex quantum Hamilton–Jacobi formalism. Chem. Phys. Lett. 458, 239 (2008)
Borondo, F., Luque, A., Villanueva, J., Wisniacki, D.A.: A dynamical systems approach to Bohmian trajectories in a 2d harmonic oscillator. J. Phys. A 42, 495103 (2009)
Cesa, A., Martin, J., Struyve, W.: Chaotic Bohmian trajectories for stationary states. J. Phys. A 49, 395301 (2016)
Sanz, Á.S.: Atom-diffraction from surfaces with defects: a Fermatian, Newtonian and Bohmian joint view. Entropy 20, 451 (2018)
Tzemos, A.C., Contopoulos, G., Efthymiopoulos, C.: Origin of chaos in 3-d Bohmian trajectories. Phys. Lett. A 380, 3796 (2016)
Contopoulos, G., Tzemos, A.C., Efthymiopoulos, C.: Partial integrability of 3d Bohmian trajectories. J. Phys. A 50, 195101 (2017)
Tzemos, A.C., Contopoulos, G.: Integrals of motion in 3d Bohmian trajectories. J. Phys. A 51, 075101 (2018)
Tzemos, A.C., Efthymiopoulos, C., Contopoulos, G.: Origin of chaos near three-dimensional quantum vortices: a general Bohmian theory. Phys. Rev. E 97, 042201 (2018)
Tzemos, A.C., Contopoulos, G., Efthymiopoulos, C.: Bohmian trajectories in an entangled two-qubit system. Phys. Scr. 94, 105218 (2019)
Tzemos, A.C., Contopoulos, G.: Chaos and ergodicity in an entangled two-qubit Bohmian system. Phys. Scr. 95, 065225 (2020)
Tzemos, A.C., Contopoulos, G.: Ergodicity and Born’s rule in an entangled two-qubit Bohmian system. Phys. Rev. E 102, 042205 (2020)
Tzemos, A., Contopoulos, G.: The role of chaotic and ordered trajectories in establishing Born’s rule. Phys. Scr. 96, 065209 (2021)
Valentini, A.: Signal-locality, uncertainty, and the subquantum h-theorem. I. Phys. Lett. A 156, 5 (1991)
Valentini, A.: Signal-locality, uncertainty, and the subquantum h-theorem. II. Phys. Lett. A 158, 1 (1991)
Valentini, A., Westman, H.: Dynamical origin of quantum probabilities. Proc. R. Soc. A 461, 253 (2005)
Tzemos, A., Contopoulos, G.: Bohmian quantum potential and chaos. Chaos Sol. Fract. 160, 112151 (2022)
Contopoulos, G., Efthymiopoulos, C., Harsoula, M.: Order and chaos in quantum mechanics. Nonlinear Phen Comput. Syst. 11, 107 (2008)
Acknowledgements
This research was conducted in the framework of the program of the RCAAM of the Academy of Athens “Study of the dynamical evolution of the entanglement and coherence in quantum systems”.
Funding
There are no ethical issues nor external funding associated with this work.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Conflict of interest
On behalf of all authors, the corresponding author states that there is no conflict of interest.
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Appendix 1: Finding the Nodal Points
Appendix 1: Finding the Nodal Points
The nodal points are of fundamental importance in the study of Bohmian chaos. These points are mathematical singularities of the Bohmian flow. Quantum particles close to a nodal point have large velocities, forming spiral vortices around it for some time. However, later the particles escape from the neighbourhood of the node. These esapes happen in two cases
-
1.
when the nodal point acquires a large velocity when going or coming from infinity;
-
2.
when a moving nodal point approaches and collides with a fixed (non moving) nodal point. This second mechanism appeared for the first time in the present paper.
After the escape the particle wanders around the configuration space until it comes close to the same or another nodal point and so on.
The evolution of the nodal points is not dictated by the Bohmian equations of motion but from their defining set of equations
The solutions of these equations become singular from time to time. These are the times where the nodal points go to or come from infinity.
However, the solutions of (34) can be found analytically only if the quantum numbers m and n are small. But if m and n are large, then in most cases the nodal points are found only numerically. Namely, one needs first to detect graphically where the velocities of the Bohmian flow form vortices (as in Fig. 2) and then to plot successively the Bohmian velocity field by gradually increasing the time and spot the moving nodal points at the centers of the vortices.
In the present paper we followed this method and put the successive figures into video simulations, where the trajectories of the nodal points became evident. Furthermore, in the same way we found the positions of the X-points by observing the points from which emanate the two stable and two unstable eigendirections.
Rights and permissions
About this article
Cite this article
Tzemos, A.C., Contopoulos, G. Bohmian Chaos in Multinodal Bound States. Found Phys 52, 85 (2022). https://doi.org/10.1007/s10701-022-00599-1
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/s10701-022-00599-1