arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2003.04589cond-mat.mes-hallcond-mat.stat-mech
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强系统-储层耦合下的非绝热粒子和能量泵

Nonadiabatic particle and energy pump at strong system-reservoir coupling

Eduardo C. Cuansing, Jian-Sheng Wang, Juzar Thingna

摘要:

本文研究了非绝热泵浦中的电子动力学和能流。该泵是一个量子点纳米结,具有随时间变化的栅极电位和隧道耦合到引线。电极导线是无偏的,并保持在相同的温度和化学势。我们发现,同步变化的栅极和隧道耦合可以泵电子和能量从左到右铅。受量子热机的启发,我们设计了一个四冲程的操作协议,可以最佳地泵送能量,因此,我们研究了能量传递和设备的性能系数。我们比较我们的设备,二冲程泵,并发现后者的较低的性能是由于能量电流的双向流动导致低净能量电流。我们的四冲程泵的性能可以得到改善,到一定程度上,通过增加净能量所携带的泵送电子通过能量充电通过栅极电位。这是通过增加泵协议中的能量充放电冲程的持续时间来实现的。然而,尽管对于长的充注和排放冲程有大的能量输出,但是维持冲程所需的能量也变得很大,从而导致停滞的泵性能。我们的泵浦仅在强铅耦合区有效工作,在弱耦合区由于净输出能量反向流动而成为哑弹。我们使用非平衡格林函数技术来计算电流,并捕捉强铅通道耦合的影响,同时将三个随时间变化的参数。我们的工作结果可以帮助设计高性能的量子泵。

英文摘要:

We study the dynamics of electron and energy currents in a nonadiabatic pump. The pump is a quantum dot nanojunction with time-varying gate potential and tunnel couplings to the leads. The leads are unbiased and maintained at the same temperature and chemical potential. We find that synchronized variations of the gate and tunnel couplings can pump electrons and energy from the left to the right lead. Inspired by quantum heat engines, we devise a four-stroke operating protocol that can optimally pump energy and hence, we investigate energy transfer and the coefficient of performance of the device. We compare our device to a two-stroke pump and find that the latter's lower performance is due to the bi-directional flow of energy currents resulting in low net energy currents. The performance of our four-stroke pump can be improved, up to a point, by increasing the net energy carried by the pumped electrons through energy charging via the gate potential. This is achieved by increasing the durations of energy charging and discharging strokes in the pump's protocol. However, despite the large energy output for long charging and discharging strokes, the energy required to maintain the strokes become large too resulting in a stagnant pump performance. Our pump operates effectively only in the strong lead coupling regime and becomes a dud in the weak coupling regime due to the net output energy flowing in the reverse direction. We use nonequilibirum Green's functions techniques to calculate the currents and capture the effects of strong lead-channel coupling exactly while simultaneously incorporating three time-varying parameters. Results from our work could aid in the design of high-performance quantum pumps.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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