Molecular arrays for dipole-based quantum information processing

随着量子信息处理（QIP）领域的成熟，它的目标也越来越成熟。特别是，我们正在寻找更现实和更好的可扩展系统，用于新的应用领域和与物理学其他领域更强的交叉。在这一建议中，我们正在处理所有这些目标。我们建议深化和扩大我们对QIP极性分子的研究，特别是着眼于可行性，可扩展性，以及与新型固态和混合系统的连接。我们希望探索类似的设置，以实现高效的确定性光量子计算系统，这些系统也可以用于高效的开关和晶体管。首先，我们希望扩展使用单极分子作为量子比特的想法。极性分子是理想的，因为最近在冷却和捕获方面取得了快速进展，有希望获得与中性原子相似的密度，并且像离子一样易于操作。我们描述了一个确定性和强大的计划，我们可以开关分子的偶极矩和关闭使用丰富的层次结构的分子。在这里，我们想建议，（i）基于极性分子的QIP的通用标准，（ii）使用固态稀有气体基质作为理想的和新颖的结构，其中分子可以非常接近地存储并且几乎没有相对距离的不确定性，从而最大化偶极-偶极相互作用的潜力，甚至超过最近邻相互作用，（iii）混合型纳米纤维/分子阱设计，以捕获和耦合分子，潜在地在所谓的？分子芯片该提案第二部分的目标是引入偶极阵列作为确定性光量子计算的工具。这个想法是将光子视为量子比特。由于光子不直接相互作用，因此必须引入非线性以创建双量子位门。我们提出通过发送暗态极化激元（光子分子耦合激发）通过偶极-偶极相互作用的偶极介质来产生单光子非线性，光子在传播过程中积累了一个非线性相移，可以解释为一个相位门。我们建议（i）详细描述这个过程，包括密度、传播长度、耦合和偶极-偶极相互作用强度之间的相互关系，以创建一个有效的相位门;（ii）概述最重要的退相干源，如非对称激发和声子以及它们在特定设置下的典型强度;（iii）为了对抗退相干，调查使用所谓的？多体保护歧管？其引入对称和非对称状态流形之间的偏差，从而减轻声子衰减;（iv）研究最佳维度和几何形状，并将其与提案第一部分中建议的类似架构相连接;以及（v）展望与所提出的想法相关的新型固态设置，例如Si表面量子点和半导体束缚激子。

As the field of quantum information processing (QIP) matures, so do its goals. In particular, we are looking for more realistic and better scalable systems, for novel areas of application and stronger crossfertilization with other areas in physics. In this proposal, we are addressing all of these goals. We propose to deepen and expand our investigation of polar molecules for QIP, specifically with a view towards feasibility, scalability, and connection with novel solid state and hybrid systems. We want to explore similar setups for efficient deterministic optical quantum computing systems that also could be used for efficient switches and transistors.First, we want to expand the idea of using single polar molecules for qubits. Polar molecules are ideal because of both recent fast progress in cooling and trapping promising similar densities as neutral atoms and of ion-like ease of manipulation. We described a deterministic and robust scheme where we can switch molecular dipole moments on and off using the rich level hierarchies in molecules. Here, we want to suggest, (i) generalized criteria for polar molecule-based QIP, (ii) the use of solid state rare gas matrices as an ideal and novel architecture in which molecules can be stored very closeand with nearly no relative distance uncertainties, thus maximizing the potential of the dipole-dipole interaction even beyond nearest-neighbor interactions, (iii) a hybrid-type nano-fiber/molecular trap design to both trap and couple the molecules, potentially on a so-called ?molecular chip. The objective of the second part of the proposal is to introduce dipolar arrays as tools for deterministic optical quantum computation. The idea of this is to treat photons as qubits. Since photons do not interact directly, a non-linearity has to be introduced in order to create a two-qubit gate. We propose to create singlephoton nonlinearities by sending dark-state polaritons, photon molecule coupled excitations, through a dipolar medium subject to dipole-dipole interactions.While propagating, the photons thus accumulate a nonlinear phase shift that can be interpreted as a phase gate. We propose to (i) describe in detail the process including interrelation between density, propagation length, coupling, and dipole-dipole interaction strength in order to create an efficient phase gate; (ii) to give an overview over the most important decoherence sources, such as non-symmetric excitations and phonons and their typical strengths for particular setups; (iii) in order to battle decoherence to investigate the possibility of using so-called ?many-body protected manifolds? which introduce a bias between symmetric and non-symmetric state manifolds and thus mitigate phonon decay; (iv) to study optimal dimensionality and geometry and connect these with similar architectures as suggested in the first part of the proposal; and (v) to give an outlook to novel solid state setups such as Si surface quantum dots and semiconductor bound excitons in connection withthe proposed idea.