New Mechanism of Transport Phenomena in Spin-Polarized Quantum Systems

Andrei E. Ruckenstein, Laurent P. Lévy

We derive the linearized spin dynamics for paramagnetic quantum liquids. In these systems, the existence of quantum-mechanical exchange in the presence of (an externally induced) broken symmetry in spin space gives rise to a coherent precession of the spins damped by diffusion. Such collective oscillations occur as a result of the precession of the spin current about a macroscopic local exchange field generated either by an external polarizing magnetic field (as in dilute nondegenerate spin-polarized gases) or by the long-lived nonequilibrium polarization (as in degenerate Fermi liquids). We use a unified approach based on the Kadanoff-Baym formulation of the kinetic equations to describe these phenomena. The connection between strongly and weakly interacting paramagnetic systems is made obvious by considering two special cases: (1) a weakly interacting spin-polarized quantum gas and (2) a parametrization of strongly correlated degenerate Fermi liquids in terms a weakly interacting gas of ``quasiparticles.'' Transport coefficients are calculated with a novel method which may be generalizable to systems with no translational invariance.

Société française de physique

V Ulyanov

Jiaqing Yan

Aiming at the controversies over traditional polarization optics explanations and mainstream interpretations of quantum entanglement in CHSH experiments, this paper proposes a new physical conjecture: the light transmission and shielding effects of polarizers essentially result from the direction-matching screening effect between the intrinsic spin direction of photons and the grating structure of polarizers. The current CHSH experiments, which are used to prove the existence of quantum entanglement, do not confirm any theories such as non-local quantum correlation, quantum state superposition, or collapse. All experimental phenomena arise entirely from the intrinsic opposite spin matching property of photon pairs at the moment of generation. Like electron–positron pairs, photons naturally carry opposite spin states when generated in pairs. Polarization detection is only a screening observation of the existing spin states of photons, rather than a measurement that alters the quantum states of photons. Based on the classical microscopic spin mechanism, all polarization experiments and CHSH experimental observations can be explained consistently, avoiding the logical paradox of non-local action in quantum entanglement theory.

Alexander E. Meyerovich, Armen Stepaniants

C. Lhuillier, Franck Laloë

The general results obtained in the preceding article are applied to the study of transport phenomena in a spin polarized gas at low temperatures, with particular emphasis on the particle indistinguishability effects in collisions. The effects of the nuclear orientation M are treated exactly (no M expansion). First, a simple theory of spin diffusion is presented and the response of the gas to a spin orientation gradient is calculated. The spin coherences and their evolution due to the « identical-spin rotation effect » are taken into account; it is found that they can play an important role, especially in the low temperature limit. The hydrodynamic equations of evolution of M are non-linear and anisotropic. Particle indistinguishability effects give an oscillatory character to the evolution of the transverse components of M (spin oscillations). Then, a more elaborate variational method is used to study the coupling between spin diffusion and heat conduction. This effect is, again, a sheer consequence of quantum interference phenomena introduced by particle indistinguishability. Finally, isotopic mixtures of 3He and 4He are considered In addition to coupling between isotopic diffusion and heat conduction, which exists for classical systems, quantum collision effects introduce a coupling between these two modes and spin diffusion.