Dissipative quantum backflow

S.V. Mousavi, Salvador Miret-Artés

In this work, dissipative quantum backflow is studied for a superposition of two stretched Gaussian wave packets and two identical spinless particles within the Caldirola-Kanai framework. Backflow is mainly an interference process and dissipation is not able to suppress it in the first case. For two identical spinless particles, apart from interference terms, the symmetry of the wave function seems to be crucial in this dynamics. The combined properties make bosons display this effect, even for the dissipative regime but, for fermions, backflow is not exhibited in any regime, dissipative and nodissipative. The anti-symmetric character of the corresponding wave function seems to be strong enough to prevent it. For bosons, backflow is also analyzed in terms of fidelity of one-particle states which is a well-known property of two quantum states. At very small values of fidelity, this effect is not seen even for bosons.

E. Celeghini, G. Vitiello, Mario Rasetti

E. Celeghini, Mario Rasetti, Giuseppe Vitiello

Kei Iida

The particle current in a metastable Fermi liquid against a first-order phase transition is calculated at zero temperature. During fluctuations of a droplet of the stable phase, in accordance with the conservation law, not only does an unperturbed current arise from the continuity at the boundary, but a backflow is induced by the density response. Quasiparticles carrying these currents are scattered by the boundary, yielding a dissipative backflow around the droplet. An energy of the hydrodynamic mass flow of the liquid and a friction force exerted on the droplet by the quasiparticles have been obtained in terms of a potential of their interaction with the droplet.

Ulrich Weiß

S. V. Mousavi, Salvador Miret-Artés

In this work, quantum backflow for open quantum systems of two identical spinless particles is addressed within the Caldeira-Leggett (CL) approach under the presence of an opposing force and by using single Gaussian and non-Gaussian wave packets. Backflow is shown to be reduced for small opposing forces, relaxation rate, temperature and a certain degree of non-Gaussianity, but never suppressed. This effect seems to be persistent at long times when considering only one wave packet, implying that interference plays no role. This remarkable behavior is attributed to the time dependence of the width of the probability density expressed in terms of relaxation rate and temperature through the diffusion coefficient. For identical spinless particles, the so-called single-particle probability density and simultaneous/joint detection probability are evaluated. Backflow is found to be occurred only for the dissipative case, being again persistent in time only without an opposing force. Our calculations show that identical spinless fermions display a higher amount of backflow with respect to identical spinless bosons and distinguishable particles. With damping and temperature, the decoherence process, loss of being indistinguishable, is settled gradually with time. At decoherence, the nature of the particles is no longer relevant.