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arXiv · 2411.18687

Increasing quantum speed limit via non-uniform magnetic field

Srishty Aggarwal·Banibrata Mukhopadhyay·Subhashish Banerjee·Arindam Ghosh·Gianluca Gregori
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Abstract

Quantum speed limit (QSL) defines the theoretical upper bound on how fast a quantum system can evolve between states. It imposes a fundamental constraint on the rate of quantum information processing. For a relativistic spin-up electron in a uniform magnetic field, QSL increased with the magnetic field strength till around $10^{15}$ Gauss, before saturating at a saturated QSL (SQSL) of 0.2407c, where c is the speed of light. We show that by using variable magnetic fields, it is possible to surpass this limit, achieving SQSL upto 0.4-0.6c. To attain this quantum phenomenon, we solve the evolution equation of relativistic electron in spatially varying magnetic fields and find that the energies of various electron states become non-degenerate as opposed to the constant magnetic field case. This redistribution of energy is the key ingredient to accomplish higher QSL and, thus, a high information processing speed. We further explore how QSL can serve as a bridge between relativistic and non-relativistic quantum dynamics, providing insights via the Bremermann-Bekenstein bound, a quantity which constrains the maximal rate of information production. We also propose a practical experimental setup to realize these advancements. These results hold immense potential for propelling fields of quantum computation, thermodynamics and metrology.

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Srishty Aggarwal, Banibrata Mukhopadhyay, Subhashish Banerjee, Arindam Ghosh, Gianluca Gregori. 2024-11-27. Increasing quantum speed limit via non-uniform magnetic field. https://arxiv.org/abs/2411.18687

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