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

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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.