Graphic sketch of a three-level quantum heat engine model working with two noninteracting fermions in a 1 D box trap. At instants 1 and 4, the two particles stays in the lowest two energy levels, while at instants 2 and 3, the two particles stay in the first and second excited energy levels. In the process 1 → 2 (3 → 4) the system absorbs (releases) energy from (to) energy bath I (II) and the energy of the system is kept unchanged at a constant energy EH (EC ). In the adiabatic processes 2 → 3 and 4 → 1 the two-particle system is decoupled from the energy bath and stays in fixed states.
Schematic diagram of a quantum heat engine cycle in the plane of the width L and force F(L). The quantum states of the two particles and the values of the potential width at the four special instants are as follows: |u 1⟩, |u 2⟩ and L 1 at the starting instant 1 of the process 1 → 2, |u 2⟩, |u 3⟩ and at the starting instant 2 of the process 2 → 3, |u 2⟩, |u 3⟩ and L 3 at the starting instant 3 of the process 3 → 4, and |u 1⟩, |u 2⟩ and at the starting instant 4 of the process 4 → 1.
The dimensionless power output P* (left) and efficiency η (right) vs the parameter r with r ≤ 50. In the left side, the inset figure P* vs r with r ≤ 7; in the right side, curve a (α = 0), curve b (α = 0.03), curve c (α = 0.08), and curve d (α = 0.15) are presented.
The dimensionless power output P* vs the efficiency η. Curve a (α = 0), curve b (α = 0.03), curve c (α = 0.08), and curve d (α = 0.15) are presented.
The values of rm η , ηmp, and ηmax for given parameter α.
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