Additional Longitudinal Field Research Articles

Confinement and entanglement dynamics on a digital quantum computer

Confinement describes the phenomenon when the attraction between two particles grows with their distance, most prominently found in quantum chromodynamics (QCD) between quarks. In condensed matter physics, confinement can appear in quantum spin chains, for example, in the one dimensional transverse field Ising model (TFIM) with an additional longitudinal field, famously observed in the quantum material cobalt niobate or in optical lattices. Here, we establish that state-of-the-art quantum computers have reached capabilities to simulate confinement physics in spin chains. We report quantitative confinement signatures of the TFIM on an IBM quantum computer observed via two distinct velocities for information propagation from domain walls and their mesonic bound states. We also find the confinement induced slow down of entanglement spreading by implementing randomized measurement protocols for the second order Rényi entanglement entropy. Our results are a crucial step for probing non-perturbative interacting quantum phenomena on digital quantum computers beyond the capabilities of classical hardware.

Improvement of turn-on time of liquid-crystal phase retarder by using an additional control voltage

We investigate theoretically and experimentally the process of turn-on time control of a nematic liquid crystal (NLC) based phase retarder by means of an additional control voltage. We propose a theoretical model of reorientation of NLC molecules in crossed electric fields (conventional transverse field and additional longitudinal field). The dynamics of reorientation of NLC molecules is considered depending on the ratio of amplitudes of control voltages. We show the possibility to reduce the turn-on time in NLC-based phase-retarder management by means of two control voltages.