Bifurcations of Liouville tori in a system of two vortices of positive intensity in a Bose-Einstein condensate

In this paper we consider a completely Liouville integrable Hamiltonian system with two degrees of freedom, which describes the dynamics of two vortex filaments in a Bose-Einstein condensate enclosed in a harmonic trap. For vortex pairs of positive intensity detected bifurcation of three Liouville tori into one. Such bifurcation was found in the integrable case of Goryachev-Chaplygin-Sretensky in the dynamics of a rigid body. For the integrable perturbation of the physical parameter of the intensity ratio, identified bifurcation proved to be unstable, which led to bifurcations of the type of two tori into one and vice versa.

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Spin-momentum entanglement in a Bose–Einstein condensate

Physical Chemistry Chemical Physics ◽

10.1039/d0cp03945d ◽

2020 ◽

Vol 22 (44) ◽

pp. 25669-25674

Author(s):

Sumit Suresh Kale ◽

Yijue Ding ◽

Yong P. Chen ◽

Bretislav Friedrich ◽

Sabre Kais

Keyword(s):

Degrees Of Freedom ◽

Raman Laser ◽

Einstein Condensate ◽

Spin States ◽

Field Coupling ◽

Bose Einstein Condensate ◽

Bose Einstein ◽

Spin Momentum

Mechanisms including two types of Raman laser coupling (Ω1 & Ω2) and rf field coupling (Ωrf) are applied to drive transitions between different hyperfine spin states. We investigated the entanglement between the spin and momentum degrees of freedom.

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Bose polaron as an instance of quantum Brownian motion

Quantum ◽

10.22331/q-2017-09-27-30 ◽

2017 ◽

Vol 1 ◽

pp. 30 ◽

Cited By ~ 41

Author(s):

Aniello Lampo ◽

Soon Hoe Lim ◽

Miguel Ángel García-March ◽

Maciej Lewenstein

Keyword(s):

Brownian Motion ◽

Langevin Equation ◽

Degrees Of Freedom ◽

Interaction Strength ◽

Einstein Condensate ◽

Generalized Langevin Equation ◽

Quantum Gas ◽

Quantum Brownian Motion ◽

Bose Einstein Condensate ◽

Bose Einstein

We study the dynamics of a quantum impurity immersed in a Bose-Einstein condensate as an open quantum system in the framework of the quantum Brownian motion model. We derive a generalized Langevin equation for the position of the impurity. The Langevin equation is an integrodifferential equation that contains a memory kernel and is driven by a colored noise. These result from considering the environment as given by the degrees of freedom of the quantum gas, and thus depend on its parameters, e.g. interaction strength between the bosons, temperature, etc. We study the role of the memory on the dynamics of the impurity. When the impurity is untrapped, we find that it exhibits a super-diffusive behavior at long times. We find that back-flow in energy between the environment and the impurity occurs during evolution. When the particle is trapped, we calculate the variance of the position and momentum to determine how they compare with the Heisenberg limit. One important result of this paper is that we find position squeezing for the trapped impurity at long times. We determine the regime of validity of our model and the parameters in which these effects can be observed in realistic experiments.

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Spontaneous symmetry breaking in persistent currents of spinor polaritons

Scientific Reports ◽

10.1038/s41598-021-01812-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Evgeny Sedov ◽

Sergey Arakelian ◽

Alexey Kavokin

Keyword(s):

Symmetry Breaking ◽

Spontaneous Symmetry Breaking ◽

Degrees Of Freedom ◽

Continuous Wave ◽

Rotational Symmetry ◽

Einstein Condensate ◽

Persistent Currents ◽

Optical Pump ◽

Bose Einstein Condensate ◽

Bose Einstein

AbstractWe predict the spontaneous symmetry breaking in a spinor Bose–Einstein condensate of exciton-polaritons (polaritons) caused by the coupling of its spin and orbital degrees of freedom. We study a polariton condensate trapped in a ring-shaped effective potential with a broken rotational symmetry. We propose a realistic scheme of generating controllable spinor azimuthal persistent currents of polaritons in the trap under the continuous wave optical pump. We propose a new type of half-quantum circulating states in a spinor system characterized by azimuthal currents in both circular polarizations and a vortex in only one of the polarizations. The spontaneous symmetry breaking in the spinor polariton condensate that consists in the switching from co-winding to opposite-winding currents in opposite spin states is revealed. It is characterized by the change of the average orbital angular momentum of the condensate from zero to non-zero values. The radial displacement of the pump spot and the polarization of the pump act as the control parameters. The considered system exhibits a fundamental similarity to a superconducting flux qubit, which makes it highly promising for applications in quantum computing.

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