Quantum-Battery-Powered Geometric Landau-Zener Interferometry

TL;DR

This paper explores how a quantum battery, modeled as a bosonic mode, can power geometric Landau-Zener interferometry in a superconducting qubit, revealing quantum effects and back-action absent in classical drives.

Contribution

It introduces a quantum-battery-powered geometric interferometry scheme, analyzing finite photon number effects and phase reference requirements, extending classical control to quantum energy sources.

Findings

Photon-number-resolved avoided crossings affect interferometry contrast.

Finite quantum batteries induce sector-resolved quantum evolution and back-action.

Reducing photon-number fluctuations alone is insufficient for geometric control.

Abstract

Classical microwave drives are usually treated as ideal phase-coherent work sources for superconducting-qubit control. What if such a drive is replaced by a finite quantum battery. As a demanding benchmark, we consider echo-refocused geometric Landau--Zener interferometry powered by a single quantized bosonic mode. The qubit--battery dynamics are described by a Jaynes--Cummings Hamiltonian, while the echo pulse is retained as a qubit-only refocusing operation that cancels the dynamical phase. In the macroscopic coherent-state limit, the usual classical geometric interferometer is recovered. At finite mean photon number, however, the Jaynes--Cummings coupling generates photon-number-resolved avoided crossings with gaps $\Omega_n=2g\sqrt{n}$. The qubit-only echo redistributes amplitudes between neighboring excitation sectors, so the finite-battery protocol is not a single classical interferometer but a coherent sector-resolved quantum evolution. This produces contrast loss, interferogram distortions, and measurable battery back-action. We further show that reducing photon-number fluctuations alone is not sufficient: geometric control requires a first-order phase reference. Geometric Landau--Zener interferometry therefore provides a practical benchmark for certifying phase-coherent quantum-battery energy.