标题： 基于腔辅助的原子拉曼记忆超越不良腔极限：四波混频的影响 显示英文标题

标题： Cavity-assisted atomic Raman memories beyond the bad cavity limit: effect of four-wave mixing

摘要： 量子存储器不仅可以用于量子信息的存储，还可以对量子态集合进行显著的操作。因此，这种操作的速度以及能够写入和读取相对较短持续时间的信号变得很重要。以前已经考虑了在信号持续时间不比腔场寿命大很多的情况下，即超出不良腔极限的情况下，腔增强原子拉曼存储器的效率限制。在本工作中，我们研究了从腔辅助存储器中检索相对较短信号时产生的四波混频噪声，从而补充了其他作者最近的考虑，他们主要集中在大腔衰减率的极限上。四波混频噪声通常被认为是重要的因素，能够阻止在各种原子、固态等实现中达到高质量的存储器。相对于由腔支持的量化信号，边带噪声源在四波混频中起着重要作用。我们提出了一种方法，可以使用基于噪声源的双带谱过滤的统一理论框架，来考虑腔辅助原子存储器中的不同物理起源的边带量子噪声源。我们证明，在这种光谱选择性存储器中，边带原子噪声源与进入腔的边带量化场一样，对检索信号的四波混频噪声有重要贡献。 显示英文摘要

摘要： Quantum memories can be used not only for the storage of quantum information, but also for substantial manipulation of ensembles of quantum states. Therefore, the speed of such manipulation and the ability to write and retrieve the signals of relatively short duration becomes important. Previously there have been considered the limits on efficiency of the cavity-enhanced atomic Raman memories for the signals whose duration is not much larger than the cavity field lifetime, that is, beyond the bad cavity limit. We investigate in this work the four-wave mixing noise that arises by the retrieval of the relatively short signals from the cavity-assisted memories, thus complementing recent considerations by other authors, who mainly concentrated on the limit of large cavity decay rate. The four-wave mixing noise is commonly recognized as an important factor, able to prevent achieving a high memories quality in a variety of the atomic, solid state etc. implementations. The side-band noise sources (with respect to the quantized signal, supported by the cavity) play important role in the four-wave mixing. We propose an approach that allows one to account for the side-band quantum noise sources of different physical origin in the cavity-assisted atomic memories using a unified theoretical framework, based on a two-band spectral filtering of the noise sources. We demonstrate that in such spectrally-selective memories the side-band atomic noise sources essentially contribute to the four-wave mixing noise of the retrieved signal on a par with the side-band quantized field entering the cavity.