RUI: Clock Transitions, Coherence and Quantum Dynamics in Molecular Nanomagnets

非技术摘要：量子计算和量子信息的新兴领域依赖于控制量子比特的量子态的能力，量子比特是用于量子信息处理的物理系统。与以零或一存储信息的经典比特不同，量子比特可以放入零态和一态的量子叠加中。此外，量子比特可以相互纠缠，以创建不能被描述为属于任何单个量子比特的独特状态。叠加和纠缠是赋予量子计算潜在力量的量子基础，这种力量伴随着一定的微妙：量子计算机中存储和处理的信息很容易受到与环境中不可控元素的相互作用的干扰，例如波动的磁场或振动。该项目的重点是将分子纳米磁铁用作量子比特，并了解和缓解影响磁体保留量子信息能力的环境因素。所谓的时钟转换可以帮助磁体免受波动磁场的影响。在这项研究中，微波光子被用来控制这些磁体的磁态，并测量量子信息在这些系统中可以存储多长时间，即相干时间。在进行这项研究的过程中，该团队正在研究这些磁铁在微波辐射存在下的基本量子性质。这项研究是在一个以本科生为主的机构进行的，本科生-学者和研究生参与其中。这些研究人员都在获得宝贵的研究技能，这些技能将进一步推动他们在学术界和快速增长的商业量子信息领域的科学和相关技术领域的职业发展。技术摘要：量子计算和量子信息的新兴领域需要具有长相干时间的量子比特，这些量子比特也很容易通过外部控制参数进行操作。这个项目的重点是使用分子纳米磁铁作为量子比特，了解和缓解环境自由度的退相干。这个项目中研究的分子磁体表现出“时钟跃迁”，可以减少波动磁场的退离效应。利用脉冲电子自旋共振技术，控制了这些分子的量子态，并测量了它们的相干时间。通过比较时钟跃迁时的相干时间与系统调谐远离时钟跃迁时测量的相干时间，研究了消相干的机制。此外，研究人员正在探索各种脉冲方案，以动态地将磁铁从环境波动中分离出来。脉冲微波辐射也被用来研究使用分子磁体作为全息存储量子信息的介质。在进行这项研究的过程中，该团队正在研究这些磁铁与微波辐射场耦合时的基本量子性质。这项研究是在一个以本科生为主的机构进行的，本科生-学者和研究生参与其中。这些研究人员都获得了宝贵的研究技能，这些技能将进一步促进他们在科学和技术领域的职业发展。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-Technical Abstract:The burgeoning field of quantum computation and quantum information relies on the ability to control the quantum states of qubits, the physical systems used for quantum information processing. Unlike classical bits, in which information is stored as zeros or ones, qubits can be put into quantum superpositions of zero and one states. In addition, qubits can be entangled with one another to create unique states that cannot be described as belonging to any individual qubit. Superposition and entanglement are the quantum underpinnings that give quantum computation its potential power, a power that is accompanied by a certain delicacy: the information stored and processed in a quantum computer can easily be disturbed by interactions with uncontrolled elements of the environment, such as fluctuating magnetic fields or vibrations. This project focuses on employing molecular nanomagnets as qubits and understanding and mitigating the environmental elements that affect the magnets’ ability to retain quantum information. So-called clock transitions can help isolate the magnets from the effects of fluctuating magnetic fields. In this research, microwave photons are used to control the magnetic states of these magnets and to measure how long quantum information can be stored in these systems, the coherence time. In the process of conducting this research, the team is investigating fundamental quantum properties of these magnets in the presence of microwave radiation. The research is being conducted at a primarily undergraduate institution with the participation of undergraduate student-scholars and graduate students. These researchers are all gaining valuable research skills that will further the development of their careers in scientific and related technical fields in academia and the rapidly growing commercial quantum information sector. Technical Abstract:The burgeoning field of quantum computing and quantum information requires qubits with long coherence times that are also easy to manipulate with external control parameters. This project focuses on employing molecular nanomagnets as qubits and understanding and mitigating the decoherence from environmental degrees of freedom. The molecular magnets studied in this project exhibit “clock transitions” that reduce the decohering effects of fluctuating magnetic fields. Using pulse electron-spin resonance techniques, the quantum states of these molecules are controlled, and their coherence times are measured. Mechanisms of decoherence are investigated by comparing the coherence times at clock transitions with those measured when the system is tuned away from clock transitions. In addition, the researchers are exploring various pulse schemes to dynamically decouple the magnets from decohering environmental fluctuations. Pulsed microwave radiation is also being employed to investigate using an ensemble of molecular magnets as a medium for the holographic storage of quantum information. In the process of conducting this research, the team is investigating fundamental quantum properties of these magnets when coupled to a microwave radiation field. The research is being conducted at a primarily undergraduate institution with the participation of undergraduate student-scholars and graduate students. These researchers are all gaining valuable research skills that will further the development of their careers in scientific and technical fields.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.