Department of Optics, Faculty of Science, Palacký University, 17. listopadu 1192/12, 779 00, Olomouc, Czech Republic.
Sci Rep. 2022 Dec 27;12(1):22455. doi: 10.1038/s41598-022-26450-1.
We investigate assisted enhancement of quantum coherence in a bipartite setting with control and target systems, which converts the coherence of the control qubit into the enhanced coherence of the target qubit. We assume that only incoherent operations and measurements can be applied locally and classical information can be exchanged. In addition, the two subsystems are also coupled by a fixed Hamiltonian whose interaction strength can be controlled. This coupling does not generate any local coherence from incoherent input states. We show that in this setting a measurement and feed-forward based protocol can deterministically enhance the coherence of the target system while fully preserving its purity. The protocol can be iterated and several copies of the control state can be consumed to drive the target system arbitrarily close to a maximally coherent state. We experimentally demonstrate this protocol with a photonic setup and observe the enhancement of coherence for up to five iterations of the protocol.
我们研究了在具有控制和目标系统的二分量设置中辅助增强量子相干性的问题，该方法将控制量子位的相干性转换为目标量子位的增强相干性。我们假设只能应用非相干操作和测量，并且可以交换经典信息。此外，两个子系统还通过固定哈密顿量耦合，其相互作用强度可以控制。这种耦合不会从非相干输入态中产生任何局部相干性。我们表明，在这种情况下，可以基于测量和前馈协议确定性地增强目标系统的相干性，同时完全保持其纯度。该协议可以迭代，并且可以消耗多个控制状态副本将目标系统任意逼近最大相干态。我们使用光子装置实验验证了该协议，并观察到该协议最多可迭代五次，相干性得到增强。
