The molecular spins have a high potential of being used in future micron-scale devices dealing with either classical or quantum aspects of information technology. Recently it has been shown that "man-made" spins can behave quantum mechanically under specific conditions. The goal of this Faculty Early Career Development (CAREER) project at the Florida State University is to investigate the quantum dynamics of molecular spins coupled strongly to resonant photons, with an eye on potential implementations in the information technology field. Spin detection will be accomplished by coupling the spin to an electro-magnetic field inside specially designed microscopic cavities. Achieving single spin sensitivity is an important objective, together with the understanding of decoherence mechanisms in molecular samples. Through association with the NHMFL a broad condensed matter community will interact closely with the proposed research. The specifics of the research will be benefic for the training of undergraduate and graduate students and part of the techniques will be integrated in a graduate course on experimental methods in physics. The program will sustain a recent NHMFL initiative to develop a nation-wide network called SuperNet which will provide high-schools with physics demonstration modules.
The goal of this Faculty Early Career Development (CAREER) project at the Florida State University is to investigate the quantum dynamics of molecular spins coupled strongly to resonant photons. Fundamental questions related to quantum macroscopicity or decoherence are at hand in these samples. Potential implementations in the information technology field will be investigated as well. In particular, the study will focus on: i) quantum non-demolition observation of an ensemble of spins, ii) observation of exotic multi-photon anti-resonances in quasi-harmonic spin states and iii) single spin sensitivity. These goals have important scientific significance and will bring light to the quantum dynamics of spins in the presence of a given environment. It is proposed to couple the total spin of a molecule to the B-component of a resonant electro-magnetic field inside microscopic cavities similar to the case of resonant cavities electrically coupled to atoms or superconducting qubits. Through association with the NHMFL a broad condensed matter community will interact closely with the proposed research. The specifics of the research will be benefic for the training of undergraduate and graduate students and part of the techniques will be integrated in a graduate course on experimental methods in physics. The program will sustain a recent NHMFL initiative to develop a nation-wide network called SuperNet which will provide high-schools with physics demonstration modules.
The project is situated in the field of experimental solid-state physics, with an emphasis in the area of quantum effects at nanoscopic scale. The focus is on quantum magnetism in spin systems interacting with photons. The project carries on spin dynamics in diluted spin systems and molecular magnets, and our studies relate to the area of spin-based quantum computing. Atomic spins carry extremely small magnetic moments, characterized by well defined quantum (or discrete) numbers which are differentiated by their energy levels when the spins are placed in magnetic fields. We demonstrate that spins can be manipulated to exist in a superposition of two or more such levels (or states) by using resonant microwave pulses of one or more photons. The ability of a spin to sustain such complex state is directly related to its quantum coherence. A pivotal aspect of the project is based on the observation that coherence related phenomena in solid-state quantum physics do show increasing similarities with effects studied in the past in atoms (in dilute gases). Therefore, techniques applied to quantum optics in atomic gases are blended in this project into the rich physics of quantum magnets resulting in great benefits in the long run. Spins – as a magnetic property of electrons - are one of the main players in future information processing and storing schemes. The process of manipulating quantum spins is a delicate process, sensitive to any decoherence source, and photons are an ideal choice to perform the task as they interact with quantum systems in predictable ways. Of particular interest to our studies are the resonant modes in electromagnetic cavities, which have the potential of inducing the strong coupling regime, a long sought type of interaction, difficult to achieve in quantum magnetic systems. In the strong coupling case, the interaction between spins and photons outlast both photon's decay and spin (or qubit) decoherence times. One or more non-interacting two-level systems (atoms, spins, etc) are coupled to one or more photons leading to energy splitting in the combined atom-photon quantum system. We demonstrated this regime and observed such energy splitting due to interaction of spins with photons. This is an important milestone for quantum computing and communication, since it shows that in principle, spins and photons can be entangled and information can be transferred from one to another. Towards the goal of implementing such results on quantum computing devices containing superconducting chip, we study the use of superconducting loops and resonators, fabricated on small chips and placed in large magnetic fields, at very low temperatures. We reported the first use of a flux detector called squid, in fields up to 7 Tesla. Our studies on superconducting cavities demonstrated that the application of magnetic field is generating a breaking of superconducting charge carrier (the so-called non-linear Meissner effect) with an influence on the characteristics of the resonators. The project was instrumental in developing several teaching and outreach scientific tools. We developed three experimental setups for a graduate level course, and supervised the research projects of graduate and undergraduate students from Florida State University. The impact of the award extends on a larger scale by providing a research platform (the lab) where undergraduate students, other graduate students, a postdoc, school teachers (from the NHMFL-Research Experience for Teachers program) have met and interacted during various periods of time. Every summer, our group hosted students from the Research Experience for Undergraduates program (from all the country) and RET teachers. The undergraduate students and teachers teamed up and worked under group supervision on a variety of projects. For instance, we studied the resonance phenomena in large cavities, at the frequency of cell phones, and build class size demos. In another project, we show that one can use solar panels to generate DC (direct current) energy free of noise generated by 60 Hz and multiples frequencies existing in a regular power supply. This aspect is useful to master when designing research setups sensitive to noise. This project also led to the construction of a small demo intended for class use, showing the importance of the orientation of a solar panel.
