Dissipative quantum evolution of a spin system in a magnetic field

C. Wolf

By allowing for dissipative interaction between a quantum spin system and the environment we calculate the frequencies and decay rates of the components of the x spin polarization for a spin system precessing in a magnetic field when the spin system has dimensionality corresponding to S= ½,1,3/2 .PACS. No.: 03.65

Philip C. E. Stamp

J. Aliaga, G. Crespo, Araceli N. Proto

Yaoyuan Fan, Shuoyu Shi, Lang Cao +4 more

Engineering spin polarization in dissipative bosonic systems is crucial for advancing quantum technologies, especially for applications in quantum metrology and space-based quantum simulations. This work demonstrates precise magnetic moment control in multicomponent Bose gases during evaporative cooling via tailored magnetic fields. By adjusting the magnetic field gradients, null point position, and duration, we selectively tune evaporation rates of magnetic sublevels, achieving targeted spin polarization. Theoretical models, validated by numerical simulations and Stern−Gerlach experiments, reveal how magnetic fields reshape trapping potentials and spin-dependent dissipation. The results establish a dissipative spin-selection mechanism governing polarization evolution in evaporatively cooled Bose gases and provide a framework for engineering spin-polarized quantum states.

Takuya Hatomura, B. Barbara, Seiji Miyashita

Numerical simulations of magnetization reversal of a quantum uniaxial magnet under a swept magnetic field [Hatomura et al., Phys. Rev. Lett. 116, 037203 (2016)] are extended. In particular, how the ``wave packet'' describing the time evolution of the system is scattered in the successive avoided level crossings is investigated from the viewpoint of the distribution of the eigenstate populations. It is found that the peak of the distribution as a function of the magnetic field does not depend on spin-size $S$, which indicates that the delay of magnetization reversal due to the finite sweeping rate is the same in both the quantum and classical cases. The peculiar synchronized oscillations of all the spin components result in the beating of the spin length. Here, dissipative effects on this beating are studied by making use of the generalized Lindblad-type master equation. The corresponding experimental situations are also discussed in order to find conditions for experimental observations.

R. Grobe, Fritz Haake