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Gagus K. Sunnardianto

Publications and source records attributed to Gagus K. Sunnardianto.

2 recordsLinked to original sources

Noise-induced Zeno-like effect in a spin-chain quantum battery

Quantum batteries, which are energy-storage or state-storage devices that exploit unique quantum effects, are sensitive to environmental noise. Here, we demonstrate that suitably engineered noise can induce a "Zeno-like" stabilization effect of the charging process in a spin-chain quantum battery within the Heisenberg XYZ model. Focusing on a system size N=6, which balances computational cost and storage capacity, we find that the ergotropy-to-energy ratio W(t)/E_B(t) attains a maximum value of about 0.99 at a certain time parameter value. Then, by varying the noise strength in each channel, we find that not only does decoherence merely degrade performance but it may also stabilize stored energy and ergotropy in the high noise strength regime. For instance, the phase-flip channel slows charging and reduces charging power, but its discharging behavior releases energy and ergotropy more slowly, allowing the battery to be used for longer times compared to bit-flip and bit-phase-flip channels. In contrast, the bit-flip channel enables fast charging, but yields low storage and rapid energy release. Remarkably, the bit-phase-flip channel can combine the advantages of both bit-flip and phase-flip channels in the high-noise-strength regime. The bit-phase-flip channel supports accelerated charging together with enhanced storage capacity, while its discharging behavior resembles that of the bit-flip channel with rapid energy release. These results reveal that, under sufficiently strong noise, environmental decoherence induces a Zeno-like stabilization, allowing it to achieve enhanced charging performance and to stabilize stored energy and ergotropy in the spin-chain quantum battery.

quant-ph

Impact of Monoatomic Vacancies in 2D Materials on the Performance of Magnetic Tunnel Junction Devices: Insights from Configurations and Interface Interactions

We investigate the impact of monoatomic vacancies in 2D materials on the performance of magnetic tunnel junction (MTJ) devices using first-principles calculations within Density Functional Theory (DFT). Specifically, we analyze the influence on hexagonal boron nitride (hBN) with various layer configurations, uncovering distinct transmission probability patterns. Transmission calculations were conducted using the Landauer-Büttiker formula employing the Non-Equilibrium Green's Function (NEGF) method. In the Ni/hBN(V$_B$)-hBN/Ni system, a significant reduction in transmission probability was observed compared to non-vacancy configurations. However, when two hBN vacancies were considered, creating the Ni/hBN(V$_B$)-hBN(V$_B$)/Ni MTJ system, a new transmission channel mediated by vacancy localized states emerged. The introduction of a monoatomic boron vacancy in the middle hBN layer of the Ni/3hBN/Ni system revealed nuanced effects on the transmission probability, highlighting alterations in the spin minority and majority channels. Additionally, we explore the monoatomic vacancy in the graphene layer in the Ni/hBN-Gr-hBN/Ni MTJ, uncovering a unique transmission channel influenced by the proximity effect. Our findings suggest that the creation of monoatomic vacancies on the insulator barrier of 2D materials induces distinctive characteristics shaped by the interaction between the surface state of the electrode and the localized state of the monoatomic vacancy layer in the MTJ system.

cond-mat.mtrl-sci