RUI: Forbidden Transitions and Quantum Dynamics in Molecular Nanomagnets

RUI：分子纳米磁体中的禁止跃迁和量子动力学

• 批准号: 1708692
• 负责人: Jonathan Friedman
• 金额: $ 53.37万
• 依托单位: Amherst College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-15 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1708692&HistoricalAwards=false
• 关键词: RUI; Forbidden; Transitions; Quantum; Dynamics

Non-Technical Abstract:Quantum computers have the potential to solve certain problems that are intractable on any classical computer. A quantum computer takes advantage of the unique properties of quantum systems, such as interference and entanglement, to process information. The information stored and processed in a quantum computer is very delicate and can easily be corrupted by fluctuations of uncontrolled external environmental elements. Many physical systems are being investigated as potential qubits, the processing elements of quantum computers. This project focuses on exploring the viability of molecular nanomagnets as qubits. One of the project's main goals is to make use of so-called atomic-clock transitions to help isolate the magnets from external fluctuations. Using microwave photons to probe and manipulate the magnetic states of these molecules, the research team is endeavoring to learn how long quantum information can be stored in these systems before becoming degraded and how to chemically engineer the molecules to improve that benchmark. In addition, the researchers aim to implement basic quantum-computing operations on coupled molecules and assess the suitability of these nanomagnets for potential integration into a large-scale quantum processor. In tandem with these goals, the research team is investigating related fundamental quantum properties of these magnets that involve coupling them to a microwave radiation field. The research is being conducted at a primarily undergraduate institution with the participation of undergraduate student-scholars, a postdoctoral researcher and a graduate student, all working under the supervision of the PI. These researchers are all gaining valuable research skills that further the development of their careers in scientific and technical fields. Technical Abstract:Many physical systems are being investigated as potential qubits. Typically, microscopic (e.g. atomic-scale) systems have long coherence times but are difficult to control and address while macroscopic systems offer greater control but less coherence. The project focuses on exploring the viability of molecular nanomagnets as qubits. These systems occupy a middle ground in which they have qubit properties that can be tuned (through, e.g., chemical engineering) while maintaining the long coherence times of microscopic systems. The molecules under investigation exhibit so-called atomic-clock transitions, which make them less susceptible to the decohering effects of dipole or hyperfine fields. The researchers use pulsed electron-spin resonance to measure the decoherence times for these nanomagnets near atomic-clock transitions. In addition, the researchers aim to perform quantum gates (such as CNOT) on supramolecular dimers with coupled states built from clock transitions of the magnets. Such experiments may herald the development of a molecule-based, solid-state quantum processor that exploits atomic-clock transitions to limit decoherence. In tandem with these goals, the research team is investigating related fundamental quantum properties of these magnets involving coupling the magnets to a microwave resonator. The research is being conducted at a primarily undergraduate institution with the participation of undergraduate student-scholars, a postdoctoral researcher and a graduate student, all working under the supervision of the PI. These researchers are all gaining valuable research skills that further the development of their careers in scientific and technical fields.

非技术摘要：量子计算机有潜力解决某些在任何经典计算机上都难以解决的问题。 量子计算机利用量子系统的独特性质，如干涉和纠缠，来处理信息。 量子计算机中存储和处理的信息非常微妙，很容易被不受控制的外部环境元素的波动破坏。 许多物理系统正在作为潜在的量子位（量子计算机的处理元件）进行研究。 该项目的重点是探索分子纳米磁体作为量子比特的可行性。 该项目的主要目标之一是利用所谓的原子钟转换来帮助将磁体与外部波动隔离开来。 使用微波光子来探测和操纵这些分子的磁状态，研究团队正在努力了解量子信息在降解之前可以在这些系统中存储多久，以及如何对分子进行化学工程以改进该基准。 此外，研究人员的目标是在耦合分子上实现基本的量子计算操作，并评估这些纳米磁体是否适合集成到大规模量子处理器中。 为了实现这些目标，研究小组正在研究这些磁铁的相关基本量子特性，包括将它们耦合到微波辐射场。 这项研究是在一个主要是本科生的机构进行的，有本科生学者、一名博士后研究员和一名研究生参加，他们都在PI的监督下工作。 这些研究人员都获得了宝贵的研究技能，进一步发展他们在科学和技术领域的职业生涯。 技术摘要：许多物理系统正在被研究为潜在的量子比特。 通常，微观（例如原子尺度）系统具有长的相干时间，但难以控制和寻址，而宏观系统提供更大的控制，但相干性较低。 该项目的重点是探索分子纳米磁体作为量子比特的可行性。 这些系统占据了一个中间地带，其中它们具有可以被调谐的量子比特属性（例如，化学工程），同时保持微观系统的长相干时间。 研究中的分子表现出所谓的原子钟跃迁，这使得它们不太容易受到偶极场或超精细场的散肩效应的影响。 研究人员使用脉冲电子自旋共振来测量这些纳米磁体在原子钟跃迁附近的退相干时间。 此外，研究人员的目标是在超分子二聚体上执行量子门（如CNOT），其耦合状态是由磁体的时钟跃迁建立的。 这样的实验可能预示着基于分子的固态量子处理器的发展，该处理器利用原子钟跃迁来限制退相干。 为了实现这些目标，研究小组正在研究这些磁体的相关基本量子特性，包括将磁体耦合到微波谐振器。 这项研究是在一个主要是本科生的机构进行的，有本科生学者、一名博士后研究员和一名研究生参加，他们都在PI的监督下工作。 这些研究人员都获得了宝贵的研究技能，进一步发展他们在科学和技术领域的职业生涯。

项目成果

Direct spectroscopic observation of Berry-phase interference in the Ni4 single-molecule magnet

Ni4单分子磁体中Berry相干涉的直接光谱观察

• DOI: 10.1103/physrevb.102.224428
• 发表时间: 2020
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Sheehan, Brendan C.;Kwark, Robert;Collett, Charles A.;Costa, Thomaz A.;Cassaro, Rafael A.;Friedman, Jonathan R.
• 通讯作者: Friedman, Jonathan R.

Constructing clock-transition-based two-qubit gates from dimers of molecular nanomagnets

• DOI: 10.1103/physrevresearch.2.032037
• 发表时间: 2020-08-13
• 期刊: PHYSICAL REVIEW RESEARCH
• 影响因子: 4.2
• 作者: Collett, Charles A.;Santini, Paolo;Friedman, Jonathan R.
• 通讯作者: Friedman, Jonathan R.

A Clock Transition in the Cr7Mn Molecular Nanomagnet

• DOI: 10.3390/magnetochemistry5010004
• 发表时间: 2019-03-01
• 期刊: MAGNETOCHEMISTRY
• 影响因子: 2.7
• 作者: Collett, Charles A.;Ellers, Kai-Isaak;Friedman, Jonathan R.
• 通讯作者: Friedman, Jonathan R.