论文标题
量子状态转移和输入输出理论随时间逆转
Quantum state transfer and input-output theory with time reversal
论文作者
论文摘要
能够可靠地将量子状态从一个系统转移到另一个系统对于开发量子网络至关重要。实现此信息传输的一种标准方法是使用中间信息载体（例如，光子）由第一个系统发出并被第二个系统吸收。对于这种情况，人们可以通过消除中等自由度来开发有效的描述，从而在两个系统之间产生有效的直接耦合。但是，如果两个系统的光谱特性不同，则需要在达到第二个系统之前对光子的时频形状进行适当的修改。我们在这里研究当我们操纵中间光子时会产生的有效描述。我们检查了一个统一的转换，即$ U $，该时间逆转，频率转换并拉伸光子波包。我们发现，可以最好地理解对有效描述的伴随修改，从该州的时间参数的变化来看，$ρ（t）=ρ_1（\ tilde {t}）\ otimesρ_2（t）$，其中$ \ tilde {t} $是第一个系统的虚拟效果。我们将该理论应用于光学腔内的三级$λ$ - 系统，并且我们从数值上说明了如何执行单一转换$ u $导致改进的量子状态转移。
Being able to reliably transfer the quantum state from one system to another is crucial to developing quantum networks. A standard way to accomplish this transfer of information is by making use of an intermediate information carrier (e.g., a photon) that is emitted by the first system and absorbed by the second. For such a scenario one can develop an effective description by eliminating the intermediate degrees of freedom, which yields an effective direct coupling between the two systems. If, however, the spectral properties of the two systems are different, the photon's time-frequency shape needs to be appropriately modified before it reaches the second system. We study here the effective description that results when we thus manipulate the intermediate photon. We examine a unitary transformation, $U$, that time reverses, frequency translates, and stretches the photon wave packet. We find that the concomitant modifications to the effective description can best be understood in terms of a change to the state's time argument, $ρ(t) = ρ_1(\tilde{t}) \otimes ρ_2(t)$, where $\tilde{t}$ is a fictitious time for the first system that is stretched and runs backward. We apply this theory to three-level $Λ$-systems inside optical cavities, and we numerically illustrate how performing the unitary transformation $U$ results in improved quantum state transfer.
