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:1409.7490 · Physical Review A

Coupling approach for the realization of a PT -symmetric potential for a Bose-Einstein condensate in a double well

Fabian Single, Holger Cartarius, Günter Wunner, Jörg Main

Published Oct 30, 2014• 44 citations
arXivHTMLPDF

Abstract

We show how non-Hermitian potentials used to describe probability gain and loss in effective theories of open quantum systems can be achieved by a coupling of the system to an environment. We do this by coupling a Bose-Einstein condensate (BEC) trapped in an attractive double-$\ensuremath{\delta}$ potential to a condensate fraction outside the double well. We investigate which requirements have to be imposed on possible environments with a linear coupling to the system. This information is used to determine an environment required for stationary states of the BEC. To investigate the stability of the system we use fully numerical simulations of the dynamics. It turns out that the approach is viable and possible setups for the realization of a $\mathcal{PT}$-symmetric potential for a BEC are accessible. Vulnerabilities of the whole system to small perturbations can be attributed to the singular character of the simplified $\ensuremath{\delta}$-shaped potential used in our model.

DOI
10.1103/physreva.90.042123

Related papers

PT-symmetric dipolar Bose-Einstein condensates : embedding in a Hermitian system and higher-order exceptional points

Robin Gutöhrlein

Open double-well Bose-Einstein condensate systems use complex potentials to describe the in-and and outfluxes of atoms.The imaginary part of the potentials allows for the effective description of in-and out-coupling of particles.If such systems exhibit balanced gain and loss, they are effectively described by a non-Hermitian P T -symmetric Hamiltonian.P T -symmetric states obeying parity and time reversal symmetry have been shown to exist.

•Jan 1, 2017•0 citations

Stationary states of aPTsymmetric two-mode Bose–Einstein condensate

Eva-Maria Graefe

The understanding of nonlinear PT symmetric quantum systems, arising for example in the theory of Bose–Einstein condensates in PT symmetric potentials, is widely based on numerical investigations, and little is known about generic features induced by the interplay of PT symmetry and nonlinearity. To gain deeper insights it is important to have analytically solvable toy models at hand. In the present paper the stationary states of a simple toy model of a PT symmetric system previously introduced in [1, 2] are investigated. The model can be interpreted as a simple description of a Bose–Einstein condensate in a PT symmetric double well trap in a two-mode approximation. The eigenvalues and eigenstates of the system can be explicitly calculated in a straightforward manner; the resulting structures resemble those that have recently been found numerically for a more realistic PT symmetric double delta potential. In addition, a continuation of the system is introduced that allows an interpretation in terms of a simple linear matrix model. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Quantum physics with non-Hermitian operators’.

arXiv:1206.4806•Journal of Physics A Mathematical and Theoretical•Oct 23, 2012•92 citations

Bose-Einstein condensates in PT-symmetric potentials

Daniel Haag

PT symmetry, alongside its applications and possible realizations, has established itself as a hot topic in recent years. Next to its possible impact on the fundamental nature of quantum physics, it has proved to be useful in the research on open systems of all kind. While PT physics has already been very successful in the field of optics, this thesis presents numerical calculations that show how PT symmetry can be applied to the mean-field theory of ultra-cold gases, where particles are added and removed coherently from a Bose-Einstein condensate. As long as the eigenvalues of a system are continuous functions with respect to such an exchange rate of particles, PT symmetry is preserved for weak perturbations. Therefore, a prediction of these changes for high excitation numbers is incredibly valuable to ensure stable stationary realizations. Not only does the present work test such rigorous estimates with regard to their validity, it also goes beyond analytically accessible regimes and presents numerical estimations for the nonlinear description of interacting particles. With this in mind, only low excited states have to be considered when studying non-trivial modifications to the PT-symmetric double-well potential. Not only do the results at hand show that this simplest implementation of PT-symmetric concepts is extremely stable with respect to experimental inaccuracies, but such modifications give rise to possible applications. Weakening the barrier inside the double well by introducing another particle channel from the gain to the loss well has a non-trivial effect on the net transport: In general, the net current does not profit from this modification, specific configurations even allow its complete suppression. Further, not only static systems, but rotating condensates are considered. It is shown, that the net particle transport is not only possible in the presence of the rotation; the vortices in the rotating wave functions even generate the necessary current by moving in such a way that their circular current adds to the net current.

•Jan 1, 2017•0 citations

Vortices in Bose-Einstein condensates with PT -symmetric gain and loss

Lukas Schwarz, Holger Cartarius, Ziad H. Musslimani +2 more

We investigate vortex excitations in dilute Bose-Einstein condensates in the presence of complex $\mathcal{PT}$-symmetric potentials. These complex potentials are used to describe a balanced gain and loss of particles and allow an easier calculation of stationary states in open systems than in a full dynamical calculation including the whole environment. We examine the conditions under which stationary vortex states can exist and consider transitions from vortex to nonvortex states. In addition, we study the influences of $\mathcal{PT}$ symmetry on the dynamics of nonstationary vortex states placed at off-center positions.

arXiv:1702.03846•Physical Review A•May 12, 2017•29 citations

EmbeddingPT -symmetric BEC subsystems into closed hermitian systems

Jan Schnabel, Ibrokhim Iskandarov

In open double-well Bose-Einstein condensate systems which balance in- and outuxes of atoms and which are eectively described by a non-hermitian PT - symmetric HamiltonianPT -symmetric states have been shown to exist. We tackle the question of how these in- and outuxes can be realized and introduce model systems in whichPT -symmetric subsystems are embedded into a closed hermitian system. We show that such subsystems still havePT -symmetric states. In addition we examine what degree of detail is necessary to describe the PT -symmetric properties and the bifurcation structure of such a system correctly by investigating a four-mode matrix model and the full Gross-Pitaevskii equation in one dimension. We also investigate which properties the wave functions of a system must full to allow for PT -symmetric states. In particular the requirements for the phase dierence

•Jan 1, 2015•0 citations

Stationary and Dynamical Solutions of the Gross-Pitaevskii Equation for a Bose-Einstein Condensate in a PT symmetric Double Well

Holger Cartarius, Dennis Dast, Daniel Haag +3 more

We investigate the Gross-Pitaevskii equation for a Bose-Einstein condensate in a PT symmetric double-well potential by means of the time-dependent variational principle and numerically exact solutions. A one-dimensional and a fully three-dimensional setup are used. Stationary states are determined and the propagation of wave function is investigated using the time-dependent Gross-Pitaevskii equation. Due to the nonlinearity of the Gross-Pitaevskii equation the potential dependson the wave function and its solutions decide whether or not the Hamiltonian itself is PT symmetric. Stationary solutions with real energy eigenvalues fulfilling exact PT symmetry are found as well as PT broken eigenstates with complex energies. The latter describe decaying or growing probability amplitudes and are not true stationary solutions of the time-dependent Gross-Pitaevskii equation. However, they still provide qualitative information about the time evolution of the wave functions.

Acta Polytechnica•Jan 3, 2013•7 citations
We show how non-Hermitian potentials used to describe probability gain and loss in effective theories of open quantum systems can be achieved by a coupling of the system to an environment. We do this by coupling a Bose-Einstein condensate (BEC) trapped in an attractive double-\ensuremathδ\ensuremath{\delta}\ensuremathδ potential to a condensate fraction outside the double well. We investigate which requirements have to be imposed on possible environments with a linear coupling to the system. This information is used to determine an environment required for stationary states of the BEC. To investigate the stability of the system we use fully numerical simulations of the dynamics. It turns out that the approach is viable and possible setups for the realization of a PT\mathcal{PT}PT-symmetric potential for a BEC are accessible. Vulnerabilities of the whole system to small perturbations can be attributed to the singular character of the simplified \ensuremathδ\ensuremath{\delta}\ensuremathδ-shaped potential used in our model.
The understanding of nonlinear PT symmetric quantum systems, arising for example in the theory of Bose–Einstein condensates in PT symmetric potentials, is widely based on numerical investigations, and little is known about generic features induced by the interplay of PT symmetry and nonlinearity. To gain deeper insights it is important to have analytically solvable toy models at hand. In the present paper the stationary states of a simple toy model of a PT symmetric system previously introduced in [1, 2] are investigated. The model can be interpreted as a simple description of a Bose–Einstein condensate in a PT symmetric double well trap in a two-mode approximation. The eigenvalues and eigenstates of the system can be explicitly calculated in a straightforward manner; the resulting structures resemble those that have recently been found numerically for a more realistic PT symmetric double delta potential. In addition, a continuation of the system is introduced that allows an interpretation in terms of a simple linear matrix model. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Quantum physics with non-Hermitian operators’.
PT symmetry, alongside its applications and possible realizations, has established itself as a hot topic in recent years. Next to its possible impact on the fundamental nature of quantum physics, it has proved to be useful in the research on open systems of all kind. While PT physics has already been very successful in the field of optics, this thesis presents numerical calculations that show how PT symmetry can be applied to the mean-field theory of ultra-cold gases, where particles are added and removed coherently from a Bose-Einstein condensate. As long as the eigenvalues of a system are continuous functions with respect to such an exchange rate of particles, PT symmetry is preserved for weak perturbations. Therefore, a prediction of these changes for high excitation numbers is incredibly valuable to ensure stable stationary realizations. Not only does the present work test such rigorous estimates with regard to their validity, it also goes beyond analytically accessible regimes and presents numerical estimations for the nonlinear description of interacting particles. With this in mind, only low excited states have to be considered when studying non-trivial modifications to the PT-symmetric double-well potential. Not only do the results at hand show that this simplest implementation of PT-symmetric concepts is extremely stable with respect to experimental inaccuracies, but such modifications give rise to possible applications. Weakening the barrier inside the double well by introducing another particle channel from the gain to the loss well has a non-trivial effect on the net transport: In general, the net current does not profit from this modification, specific configurations even allow its complete suppression. Further, not only static systems, but rotating condensates are considered. It is shown, that the net particle transport is not only possible in the presence of the rotation; the vortices in the rotating wave functions even generate the necessary current by moving in such a way that their circular current adds to the net current.
We investigate vortex excitations in dilute Bose-Einstein condensates in the presence of complex PT\mathcal{PT}PT-symmetric potentials. These complex potentials are used to describe a balanced gain and loss of particles and allow an easier calculation of stationary states in open systems than in a full dynamical calculation including the whole environment. We examine the conditions under which stationary vortex states can exist and consider transitions from vortex to nonvortex states. In addition, we study the influences of PT\mathcal{PT}PT symmetry on the dynamics of nonstationary vortex states placed at off-center positions.
In open double-well Bose-Einstein condensate systems which balance in- and outuxes of atoms and which are eectively described by a non-hermitian PT - symmetric HamiltonianPT -symmetric states have been shown to exist. We tackle the question of how these in- and outuxes can be realized and introduce model systems in whichPT -symmetric subsystems are embedded into a closed hermitian system. We show that such subsystems still havePT -symmetric states. In addition we examine what degree of detail is necessary to describe the PT -symmetric properties and the bifurcation structure of such a system correctly by investigating a four-mode matrix model and the full Gross-Pitaevskii equation in one dimension. We also investigate which properties the wave functions of a system must full to allow for PT -symmetric states. In particular the requirements for the phase dierence
We investigate the Gross-Pitaevskii equation for a Bose-Einstein condensate in a PT symmetric double-well potential by means of the time-dependent variational principle and numerically exact solutions. A one-dimensional and a fully three-dimensional setup are used. Stationary states are determined and the propagation of wave function is investigated using the time-dependent Gross-Pitaevskii equation. Due to the nonlinearity of the Gross-Pitaevskii equation the potential dependson the wave function and its solutions decide whether or not the Hamiltonian itself is PT symmetric. Stationary solutions with real energy eigenvalues fulfilling exact PT symmetry are found as well as PT broken eigenstates with complex energies. The latter describe decaying or growing probability amplitudes and are not true stationary solutions of the time-dependent Gross-Pitaevskii equation. However, they still provide qualitative information about the time evolution of the wave functions.