Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userPredicting spinor condensate dynamics from simple principles
47
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We study the spin dynamics of quasi-one-dimensional F=1 condensates both at zero and finite temperatures for arbitrary initial spin configurations. The rich dynamical evolution exhibited by these non-linear systems is explained by surprisingly simple principles: minimization of energy at zero temperature, and maximization of entropy at high temperature. Our analytical results for the homogeneous case are corroborated by numerical simulations for confined condensates in a wide variety of initial conditions. These predictions compare qualitatively well with recent experimental observations and can, therefore, serve as a guidance for on-going experiments.
rate research
Read More
First order coherence measurements of a polariton condensate, reveal a regime where the condensate pseudo-spin precesses persistently within the driving optical pulse. Within a single 20 $mu$s optical pulse the condensate pseudo-spin performs over $10^5$ precessions with striking frequency stability. The condensate maintains its phase coherence even after a complete precession of the spin vector, making the observed state by a definition a spin coherent state. The emergence of the precession is traced to the polariton interactions that give rise to a self-induced out-of-plane magnetic field that in turn drives the spin dynamics. We find that the Larmor oscillation frequency scales with the condensate density, enabling external tuning of this effect by optical means. The stability of the system allows for the realization of integrated optical magnetometry devices with the use of materials with enhanced exciton $g$-factor and can facilitate spin squeezing effects and active coherent control on the Bloch sphere in polariton condensates.
We observe coherent spin oscillations in an antiferromagnetic spin-1 Bose-Einstein condensate of sodium. The variation of the spin oscillations with magnetic field shows a clear signature of nonlinearity, in agreement with theory, which also predicts anharmonic oscillations near a critical magnetic field. Measurements of the magnetic phase diagram agree with predictions made in the approximation of a single spatial mode. The oscillation period yields the best measurement to date of the sodium spin-dependent interaction coefficient, determining that the difference between the sodium spin-dependent s-wave scattering lengths $a_{f=2}-a_{f=0}$ is $2.47pm0.27$ Bohr radii.
We investigate the internal dynamics of the spinor Bose-Einstein Condensates subject to dissipation by solving the Lindblad master equation. It is shown that for the condensates without dissipation its dynamics always evolve along specific orbital in the phase space of ($n_0$, $theta$) and display three kinds of dynamical properties including Josephson-like oscillation, self-trapping-like oscillation and running phase. In contrast, the condensates subject to dissipation will not evolve along the specific dynamical orbital. If component-1 and component-(-1) dissipate in different rates, the magnetization $m$ will not conserve and the system transits between different dynamical regions. The dynamical properties can be exhibited in the phase space of ($n_0$, $theta$, $m$).
We present measurements and a theoretical model for the interplay of spin dependent interactions and external magnetic fields in atomic spinor condensates. We highlight general features like quadratic Zeeman dephasing and its influence on coherent spin mixing processes by focusing on a specific coherent superposition state in a F=1 $^{87}$Rb Bose-Einstein condensate. In particular, we observe the transition from coherent spinor oscillations to thermal equilibration.
We observe a spontaneous parity breaking bifurcation to a ferromagnetic state in a spatially trapped exciton-polariton condensate. At a critical bifurcation density under nonresonant excitation, the whole condensate spontaneously magnetizes and randomly adopts one of two elliptically polarized (up to 95% circularly-polarized) states with opposite handedness of polarization. The magnetized condensate remains stable for many seconds at 5 K, but at higher temperatures it can flip from one magnetic orientation to another. We optically address these states and demonstrate the inversion of the magnetic state by resonantly injecting 100-fold weaker pulses of opposite spin. Theoretically, these phenomena can be well described as spontaneous symmetry breaking of the spin degree of freedom induced by different loss rates of the linear polarizations.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
