Quantum thermal management devices based on strong coupling qubits

We study the performance of a thermal management device with small scales by considering a strong coupling between quantum qubits. A small change of the thermal current at the base will cause a great change to the thermal current at the emitter and collector, reaching its promise for large thermal amplification. The competition between the quantum coherence and the incoherence induces a significant variation in the amplification factor and consequently relates the thermal controls with quantum effects. The results obtained here will provide a feasible scheme for the realization of quantum thermal management devices.

Figure 1

The schematic diagram of a quantum thermal management device. The coherence and the heat current $Q_{BC}$ are generated by a two-qubit interaction with strength $\gamma$ between qubits $B$ and $C$. Heat currents $Q_E^g, Q_B^g$, and $Q_C^g$ are caused by the tripartite interaction with the weak interaction strength $g$.

Figure 2

The thermal conductances $\left(a\right){\sigma }_i$, (b) ${\sigma }_{ig}$, (c) ${\sigma }_{i\gamma }$, and $\left(d\right)$ the coherence between the qubits $B$ and $C$ as functions of the base temperature $T_B$. We choose the parameters $T_E=10, T_C=1, P_E=0.01, P_B=0.001, P_C=0.0001, E_E=6, E_B=10, g=0.01$, and $\gamma =2.8$.

Figure 3

(a) The heat currents $Q_B, Q_C$, and $Q_E$, (b) the two different branches $-Q_B^g$ and $Q_{\gamma }$ of the base heat current and $Q_B$, (c) the base thermal conductances ${\sigma }_B$, and (d) the amplification factors ${\alpha }_E$ and ${\alpha }_C$ as functions of the base temperature $T_B$. We choose the parameters $T_E=10, T_C=1, P_E=0.01, P_B=0.001, P_C=0.0001, E_E=6, E_B=10, g=0.01$, and $\gamma =2.5$.

Figure 4

(a) The thermal conductances ${\sigma }_B, {\sigma }_C$, and ${\sigma }_E$, and (b) the amplification factors ${\alpha }_E$ and ${\alpha }_C$ as functions of the base temperature $T_B$. The base temperature $T_B=2.1$, and the values of other parameters are the same as those used in Fig. 3.

Figure 5

The amplification factors ${\alpha }_E$ and ${\alpha }_C$ as functions of (a) the decoherence rate of the base $P_B$ and (b) the strong coupling $\gamma$. When $P_B=0.001$, an infinite amplification factor is obtained. At the point of $\gamma \approx 2.5$, an infinite amplification factor is observed. The base temperature $T_B=2.1$, and the values of other parameters are the same as those used in Fig. 3.