Scaling Up quantum computation with Molecular spins

SUQMO旨在为量子计算和模拟的新架构奠定基础，其中信息被编码在被困在分子中的自旋量子比特中，这些分子被读出并通过它们与超导谐振器的耦合进行通信。该技术在鲁棒性和可扩展性方面具有很高的潜力，基于分子构建块的微观和完美可复制的性质，以及在每个构建块中包含多个量子位的可能性，这为增加计算资源和实现容错逻辑量子位提供了额外的维度。该提案侧重于两个具体目标，这代表了实现这种磁性量子处理器的关键里程碑。首先是在分子结构中实现量子纠错码。第二个是在单个分子自旋和困在谐振器中的单个光子之间实现强或相干耦合。实现这些目标需要不同学科之间以及实验和理论方法之间的协调合作。配位和超分子化学将结合起来设计和合成承载多个量子比特的分子结构。这些系统的自旋弛豫T1和相干T2时间将通过最先进的电子顺磁波谱进行测量，并通过化学方法进行优化，达到超过100微秒的值，这两个值都需要克服误差校正相干阈值并实现与超导谐振器的强耦合。新一代的微波超导纳米谐振器，能够将微波磁场压缩到纳米级区域，将通过离子束纳米光刻技术铣削中央传输线或用单壁碳纳米管或二维超导层制造纳米桥来开发。分子将通过浸笔纳米光刻和表面反应分子配体的结合，在这些器件中形成纳米图案。在低温条件下，单个分子与超导衬底结合的相干时间将通过基于stm的泵浦探针实验来确定。最终目标是在单个分子自旋上进行电路QED实验，以实现强耦合状态，提供基本量子操作的概念验证实现，并读出它们的量子自旋态。

SUQMO aims to set the basis of a new architecture for quantum computation and simulation, in which information is encoded in spin qubits trapped in molecules that are read-out and communicate via their coupling to a superconducting resonator. This technology has a high potential for robustness and scalability, based on the microscopic and perfectly reproducible nature of the molecular building blocks and on the possibility of embodying multiple qubits in each of them, which provide an extra dimension to increase computational resources and to implement fault-tolerant logical qubits. The proposal focuses on two specific targets, which represent crucial milestones for the realization of such magnetic quantum processor. The first is the implementation of quantum error correction codes in molecular structures. The second is the attainment of strong, or coherent, coupling between an individual molecular spin and a single photon trapped in a resonator. Progress towards these targets involves a coordinated cooperation between diverse disciplines and between experimental and theoretical methods. Coordination and supramolecular chemistry will be combined to design and synthesize molecular structures hosting multiple qubits. Spin relaxation T1 and coherence T2 times of these systems will be measured by state-of-the-art electron paramagnetic spectroscopy and optimized, by means of chemical methods, to values exceeding 100 microseconds that are required both to overcome the error correction coherence thresholds and attain strong coupling to a superconducting resonator. A new generation of microwave superconducting nanoresonators, able to squeeze microwave magnetic fields into nanoscopic regions, will be developed by either milling down the central transmission line with ion-beam nanolithography or by fabricating nanobridges with single-wall carbon nanotubes or two-dimensional superconducting layers. Molecules will be nanopatterned into these devices by a combination of dip-pen nanolithography and the use of surface-reacting molecular ligands. Coherence times of individual molecules bond to superconducting substrates will be determined at low temperatures by STM-based pump-probe experiments. The final goal is to perform circuit QED experiments on individual molecular spins to achieve the strong coupling regime, provide proof-of-concept implementations of basic quantum operations and read-out their quantum spin states.