Seah Stella, Perarnau-Llobet Martí, Haack Géraldine, Brunner Nicolas, Nimmrichter Stefan
Département de Physique Appliquée, Université de Genève, 1211 Genève, Switzerland.
Naturwissenschaftlich-Technische Fakultät, Universität Siegen, Siegen 57068, Germany.
Phys Rev Lett. 2021 Sep 3;127(10):100601. doi: 10.1103/PhysRevLett.127.100601.
We present a collision model for the charging of a quantum battery by identical nonequilibrium qubit units. When the units are prepared in a mixture of energy eigenstates, the energy gain in the battery can be described by a classical random walk, where both average energy and variance grow linearly with time. Conversely, when the qubits contain quantum coherence, interference effects buildup in the battery and lead to a faster spreading of the energy distribution, reminiscent of a quantum random walk. This can be exploited for faster and more efficient charging of a battery initialized in the ground state. Specifically, we show that coherent protocols can yield higher charging power than any possible incoherent strategy, demonstrating a quantum speed-up at the level of a single battery. Finally, we characterize the amount of extractable work from the battery through the notion of ergotropy.
我们提出了一个由相同的非平衡量子比特单元为量子电池充电的碰撞模型。当这些单元制备在能量本征态的混合态时，电池中的能量增益可以用经典随机游走描述，其中平均能量和方差均随时间线性增长。相反，当量子比特包含量子相干性时，电池中会积累干涉效应，导致能量分布更快地扩散，这类似于量子随机游走。这可用于对处于基态初始化的电池进行更快、更高效的充电。具体而言，我们表明相干协议能产生比任何可能的非相干策略更高的充电功率，在单个电池层面展示了量子加速。最后，我们通过负熵的概念来表征从电池中可提取的功的量。
