Experiments will be undertaken to explore the quantum mechanical nature of a macroscopic variable -- in this case the magnetic flux F linking a SQUID (a superconducting loop containing a Josephson junction). A particular focus of this work will be to understand the effects of the environment (damping and temperature) on the evolution of F from purely classical to quantum behavior as seen in the switching of the SQUID between two fluxoid wells by tunneling through a potential barrier. The system energy can be quantized into discrete levels within each of these macroscopically distinct fluxoid wells. During tunneling, the magnetic moment of the system flips, changing by about 1010 mB --- a very macroscopic quantity. Thus these experiments will represent a physical realization of the famous Schrodinger's cat paradox resulting from the coherent superposition of macroscopically distinct states. Additionally, the experiments will permit controlled tests of the underlying theory for the interaction of quantum systems with their environment, which is applicable to many physical systems: microscopic as well as macroscopic. This work will be carried out as coupled research projects between SUNY Stony Brook and the University of Kansas. Initially, work at Kansas will focus on development of new microwave techniques for measurement of Rabi oscillations and at Stony Brook on the extension of previous techniques as well as new sample fabrication. Data and analysis will be shared between groups. %%% Experiments will be undertaken to explore the quantum mechanical nature of a macroscopic variable -- in this case the magnetic flux F linking a superconducting loop. A particular focus of this work will be to understand the effects of interactions with surrounding matter on the evolution of F from purely classical to quantum behavior as seen in the switching of the magnetic moment of the loop due to quantum mechanical tunneling. During tunneling, the magnetic moment of the system flips, changing by about ten billion times that of a single electron --- a very macroscopic quantity. Coherent oscillations of the flux will demonstrate purely quantum behavior. Additionally, the experiments will permit controlled tests of the underlying theory for the interaction of quantum systems with their environment, which is applicable to many physical systems: microscopic as well as macroscopic. This work will be carried out as coupled research projects between SUNY Stony Brook and the University of Kansas. Initially, work at Kansas will focus on development of new microwave techniques for measurement of oscillations and at Stony Brook on the extension of previous techniques as well as new sample fabrication. Data and analysis will be shared between groups. Students will receive extensive training both in fundamental physics and a variety of state-of-the-art techniques such as electronic measurements and sample fabrication, which will prepare them for both academic and industrial careers.
