Nanoconfinement, nanofluidics, new phases and their transitions for superfluid 3He

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Non-Technical AbstractThe pace of research and development is accelerating. Our everyday devices are ever more capable, cheaper, and faster. Most of these consumer items' inbuilt technology exists because of fundamental advances in condensed matter research. Future advances will happen because of curiosity driven exploration of new regimes presently accessible only in a laboratory environment. The research to be conducted in this program will examine the special properties of superfluid 3He when confined in precisely defined structures less than a thousandth of a millimeter tall, marking the transition from bulk three-dimensional behavior to a new two-dimensional regime. Undergraduate students and Ph.D students will design and fabricate these structures opening up a new area of quantum nano-fluidics. The surfaces will have to have a well-defined smoothness - and the surface coating (with pure helium 4 or helium 3 under a magnetic field) should alter the types of superfluid states ("phases") that emerge. These phases should show a property "chirality" that should have properties like a spinning top. Further, the conversion from one state to another ("phase transition") should reveal whether models of the early universe (important for our understanding of the evolution of the universe) can be tested in the laboratory. Past graduate students and undergraduates working with this research group have gone on to productive careers in academia, high-technology industries and the financial sector, and the planned research will prepare a new generation of students for challenging careers. The size range where the system transforms from a nearly three-dimensional material to a more two-dimensional system will be revealed by new phases. These new phases should exhibit novel characteristics such as highly conducting "edge states" that are scientifically "exciting" and that could, in the future form the basis of new types of devices for metrology and computation. Technical abstract:Superfluid 3He can inform research activity that extends across many fields in Physics. The project combines nanofluidics (intricate and precisely fabricated cavities with sizes tuned to the scale of the superfluid's coherence length) with low temperature physics, to expose new size effects. The experimental activity will probe excitations using transport (superfluid density and heat conductivity) as well as a novel nanoscale ultra-fine wire to act as a local thermometer or spectrometer. Researchers expect that entirely new p-wave superfluid states can be stabilized by such confinement and the balance between the superfluid ground state that preserves (3He-B) or breaks (3He-A) time reversal symmetry will also be affected by confinement. By measuring the phase diagram of confined 3He both with and without an applied magnetic field, details of the pressure and temperature dependence of the strong coupling strength will be mapped out allowing for more reliable prediction of the phase diagrams of 3He under confinement. Confinement will also provide the means to study the surface/edge excitations emerging as a result of bulk/edge correspondence. Furthermore this research activity will provide a new example of "cosmology in the laboratory". Studies of the first-order transition between the confined A and B phases, radically different from nucleation in bulk, will potentially provide a model of processes during the inflationary epoch of the early universe. New geometries will explore the physics of quantum transport across single and multiple interfaces. By combining low temperatures and nano fabrication, graduate students and undergraduates will be exposed to the exciting training ground that has prepared scientists for lead roles in academia and high-technology industries. Eventually, the new superfluids that emerge under confinement might be of interest in quantum computation.