发表机构
Nanchang University（南昌大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出通过随机相位控制测量辅助三能级量子制冷机，消除相干性反馈，最大化制冷功率，相位循环可提升约32%的制冷功率。
AI 中文摘要
倾斜的非选择性测量可以关闭三能级量子制冷机的上跃迁，但它也会产生相干性，该相干性反馈到布居数上并抑制制冷电流。我们提出了测量方位角相位 \\(\alpha\\) 的随机开环控制方案，其中每个事件独立地从概率分布 \\(P(\alpha)\\) 中采样，同时保持事件速率、极角和单事件布居转移概率固定。直接布居转移与相位无关，而相干性源携带因子 \\(e^{-i\alpha}\\)。稳态相干性的精确消除给出 \\(0\leq k_{\rm eff}[P]\leq A_m\\)，其中 \\(k_{\rm eff}[P]\\) 是上能级之间的有效布居转移速率，\\(A_m\\) 是裸直接混合速率。当固定测量耦合布居数和相干性时，上界达到当且仅当 \\(\langle e^{i\alpha}\rangle_P=0\\)，其中 \\(\langle\cdot\rangle_P\\) 表示对相位分布的平均。最小实现使用两个权重相等且相差 \\(\pi\\) 的相位：布居到相干性源及其返回布居数在生成器层面消失，而完整的直接混合保持。由于在制冷窗口中冷电流随 \\(k_{\rm eff}\\) 严格增加，相同的条件在此处考虑的独立随机相位分布中最大化稳态制冷功率。对于一组代表性参数，相位循环相对于固定相位测量将固定间隙制冷功率提高约 \\(32\\%\\)，同时保持提取的冷热量与提供的测量能量之比不变。
英文摘要
A tilted nonselective measurement can close the upper transition of a three-level quantum refrigerator, but it also generates coherence that feeds back on the populations and suppresses the cooling current. We formulate randomized open-loop control of the measurement azimuthal phase \(α\), sampled independently at each event from a probability distribution \(P(α)\), while keeping the event rate, polar angle, and single-event population-transfer probability fixed. Direct population transfer is phase independent, whereas the coherence source carries the factor \(e^{-iα}\). Exact elimination of the stationary coherence gives \(0\leq k_{\rm eff}[P]\leq A_m\), where \(k_{\rm eff}[P]\) is the effective population-transfer rate between the upper levels and \(A_m\) is the bare direct mixing rate. When the fixed measurement couples populations and coherence, the upper bound is attained if and only if \(\langle e^{iα}\rangle_P=0\), where \(\langle\cdot\rangle_P\) denotes an average over the phase distribution. The minimal realization uses two equally weighted phases separated by \(π\): the population-to-coherence source and its return to the populations then vanish at the generator level, while the full direct mixing remains. Because the cold current increases strictly with \(k_{\rm eff}\) in the refrigeration window, the same condition maximizes the stationary cooling power over the independent random-phase distributions considered here. For one representative parameter set, phase cycling increases the fixed-gap cooling power by about \(32\%\) relative to a fixed-phase measurement, while leaving the ratio of extracted cold heat to supplied measurement energy unchanged.
