@inproceedings {623,
	title = {Quantum heat engine efficiency of a small spin system with anisotropy},
	booktitle = {Proceedings of the 41st Samahang Pisika ng Pilipinas Physics Conference},
	year = {2023},
	month = {19{\textendash}21 July 2023},
	pages = {SPP-2023-3H-05},
	address = {Siargao},
	abstract = {The rise of electronic devices lower than the nanoscale shifts the focus to quantum heat engines as they have improved features than their classical counterparts. In this work, the two-spin and three-spin systems using the Lipkin-Meshkov-Glick (LMG) model as the working substance of the heat engine are considered. The efficiency of the quantum heat engine comprised of two reversible isothermal processes and two isomagnetic processes with varying spin anisotropy is investigated. The configuration with the highest anisotropy was found to yield the highest efficiency for the two-spin system, and the most isotropic case was the most efficient for the three-spin system. This is attributed to the effect of anisotropy on the energy levels of the LMG spin system.},
	url = {https://proceedings.spp-online.org/article/view/SPP-2023-3H-05},
	author = {Gene Michael P. Herman and Cristine D. Villagonzalo}
}
@inproceedings {582,
	title = {Quantum Carnot heat engine with an effective external electric field perturbation},
	booktitle = {Proceedings of the 40th Samahang Pisika ng Pilipinas Physics Conference},
	year = {2022},
	month = {19{\textendash}21 Oct 2022},
	pages = {SPP-2022-1D-03},
	address = {Legazpi City},
	abstract = {The classical approach to heat engines is not enough to study devices in the atomic scale as it utilizes spin-systems as working substances whose behavior is dictated by quantum mechanics. We constructed a quantum heat engine that follows the Carnot cycle with two reversible isothermal and isomagnetic processes in contact with heat baths of two different temperatures, based on the Lipkin-Meshkov-Glick (LMG) model. The engine runs between two magnetic fields with one kept constant and the other magnetic field varied. A perturbation in the form of an effective external electric field in the x-direction, δJx, was introduced to the system where δ << 1. Up to the second-order energy correction was determined using the time-independent perturbation theory and the unperturbed LMG eigenstates as basis. The entropy, internal energy, and the work done in each cycle were determined and used to obtain the efficiency of the system with spins N = 2. For a fixed set of values for the high-temperature heat bath and the low-temperature heat bath, this work demonstrates that the system{\textquoteright}s efficiency is dependent on δ and the varying magnetic field. The system{\textquoteright}s maximum efficiency was found to approach the value of the Carnot limit.},
	url = {https://proceedings.spp-online.org/article/view/SPP-2022-1D-03},
	author = {Gene Michael P. Herman and Cristine D. Villagonzalo}
}
