Quantum speed limit time in a magnetic resonance

TL;DR

This paper visualizes qudit spin dynamics in magnetic resonance, revealing quantum interference effects and establishing bounds on quantum speed limit times, with implications for quantum information processing.

Contribution

It introduces a visualization method for spin vector dynamics and determines the quantum speed limit bounds for multilevel spin systems, including specific minimal times for state orthogonalization.

Findings

Quantum interference of precessional and nutational effects visualized.

Bottom bounds of quantum speed limit time identified for various spins.

Minimal orthogonalization time achieved at spin S=2 under certain conditions.

Abstract

A visualization for dynamics of a qudit spin vector in a time-dependent magnetic field is realized by means of mapping a solution for a spin vector on the three-dimensional spherical curve (vector hodograph). The obtained results obviously display the quantum interference of precessional and nutational effects on the spin vector in the magnetic resonance. For any spin the bottom bounds of the quantum speed limit time (QSL) are found. It is shown that the bottom bound goes down when using multilevel spin systems. Under certain conditions the non-nil minimal time, which is necessary to achieve the orthogonal state from the initial one, is attained at spin S=2. An estimation of the product of two and three standard deviations of the spin components are presented. We discuss the dynamics of the mutual uncertainty, conditional uncertainty and conditional variance in terms of spin standard deviations. The study can find practical applications in the magnetic resonance, 3D visualization of computational data and in designing of optimized information processing devices for quantum computation and communication.