Dipolar switching for robust quantum computation with polar molecules

我们对量子信息的理解的最新进展表明，基于基本量子原理的计算设备，如干涉和纠缠，可以比任何经典计算机更有效地执行某些任务。基于这些原理的计算设备的潜在分支已经激发了大量的努力，旨在确定这些设备的信息处理能力和物理实现它们的可能方法。在量子处理器中，信息将以量子比特或量子位的叠加形式存在。为了有效地操纵量子位，它们必须以可控和连贯的方式相互作用，以保持这些叠加态。在许多研究操纵量子信息的系统中，有两个平台特别有吸引力；被捕获的离子表现出强烈的相互作用和高水平的控制，而中性原子具有很长的相干时间和成熟的冷却和捕获它们的技术。极性分子代表了一个新的平台，它结合了原子和离子的优点，甚至可能弥合与凝聚态物理方法的差距。因为它们是中性的，它们比离子更容易以致密的方式储存，而且因为它们有很强的电偶极矩，它们的相互作用比中性原子强得多，距离也长得多。此外，最近在极性分子的冷却和存储方面取得的进展为量子计算所需的单分子精确操作铺平了道路。提出的研究涉及在超冷极性分子中实现通用双量子比特逻辑门的研究，重点是可切换的偶极子-偶极子相互作用。有了这个新系统，人们可以利用许多内部分子量子态来编码和处理信息。这项工作将研究基于极性分子之间的偶极相互作用的方案，利用它们的大范围偶极矩；通过选择性地激发两个分子从低偶极态到高偶极态的跃迁，利用光学或微波跃迁，可以有效地控制相互作用。这项工作将集中在两种潜在的结构上，光学晶格和连接到超导线的微阱。对于这两种方法，我们将与我们在哈佛大学（Doyle/Lukin）和耶鲁大学（DeMille）的实验合作者密切联系。此外，我们将探索极性分子的相门阻断机制的可能性。

Recent advances in our understanding of quantum information suggest that computational devices based on fundamental quantum principles, such as interference and entanglement, can perform certain tasks considerably more efficiently than any classical computer. The potential ramifications of computing devices based on these principles have inspired a great deal of effort aimed at determining the information processing power of such devices and possible methods for physically realizing them. In quantum processors, the information would exist in the form of superpositions of quantum bits, or qubits. To usefully manipulate qubits, they must interact in a controlled and coherent manner in order to preserve these superpositions. Of the many systems studied to manipulate quantum information, two platforms are especially attractive; trapped ions exhibit strong interactions and a high level of control, while neutral atoms have very long coherence times and well developed techniques to cool and trap them. Polar molecules represent a new platform that incorporates the best of both, atoms and ions, and may even bridge the gap with condensedmatter physics approaches. Because they are neutral, they are easier to store in a dense fashion than ions, and because they have strong electric dipole moments, they interact with a much stronger and longer-range interaction than neutral atoms. In addition, the recent advances in cooling and storing of polar molecules are paving the way to the accurate manipulation of single molecules required for quantum computing. The research proposed involves the study of the implementation of universal two-qubit logic gates in ultracold polar molecules,focusing on switchable dipole-dipole interactions. With this new system, one may take advantage of the many internal molecular quantum states to encode and process information. The work will investigate schemes based on dipole interactions between polar molecules, taking advantage of their large range of dipole moments; by selectively exciting transitions from low- to high-dipole states in two molecules, using optical or microwave transitions, the interaction can effectively be controlled. The work will focus on two potential architectures, optical latticesand microtraps connected to superconducting wires. For these two approaches, we will be in close contact with our experimental collaborators at Harvard (Doyle/Lukin) and Yale (DeMille). In addition, we will explore the possibility of adapting the blockade mechanism for phase gate with polar molecules.