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arXiv · 2404.10074

Nano-welding of quantum spin-$1/2$ chains at minimal dissipation

Moallison F. Cavalcante·Marcus V. S. Bonança·Eduardo Miranda·Sebastian Deffner
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Abstract

We consider the optimal control of switching on a coupling term between two quantum many-body systems. Specifically, we (i) quantify the energetic cost of establishing a weak junction between two quantum spin-$1/2$ chains in finite time $\tau$ and (ii) identify the energetically optimal protocol to realize it. For linear driving protocols, we find that for long times the excess (irreversible) work scales as $\tau^{-\eta}$, where $\eta=1, 2$ or a nonuniversal number depending on the phase of the chains. Interestingly, increasing a $J_z$ anisotropy in the chains suppresses the excess work thus promoting quasi-adiabaticity. The general optimal control problem is solved, employing a Chebyshev ansatz. We find that the optimal control protocol is intimately sensitive to the chain phases.

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Moallison F. Cavalcante, Marcus V. S. Bonança, Eduardo Miranda, Sebastian Deffner. 2024-04-15. Nano-welding of quantum spin-$1/2$ chains at minimal dissipation. https://doi.org/10.1103/physrevb.110.064304

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