Fermions and bosons on an atom chip

Kunal K. Das, S. Aubin

We present a design for simulating quantum pumping of electrons in a mesoscopic circuit with ultracold atoms in a micromagnetic chip trap. We calculate theoretical results for quantum pumping of both bosons and fermions, identifying differences and common features, including geometric behavior and resonance transmission. We analyze the feasibility of experiments with bosonic ;{87}Rb and fermionic ;{40}K atoms with an emphasis on reliable atomic current measurements.

Richard A. Dunlap

Jason S. Alexander, VIOLETA A. PRIETO, Christopher Rowlett +2 more

We report on progress for a couple of experiments on manipulating cold atoms on a chip for quantum sensing. The first experiments are directed towards developing a compact atom interferometer on an atom chip using a double-well potential. The interferometer uses 87Rb atoms magnetically confined in an atomic waveguide produced by wires on the surface of a lithographically patterned chip. Finite element modeling of combinations of different current configurations with various external bias fields indicated a means of coherently splitting the atomic cloud through dynamically adjusting the currents and bias fields. In these experiments we investigate real-time transformations between different double-well configurations adiabatically and non-adiabatically, and study their effects on the initially trapped atoms. Coherence properties of the two atomic wavepackets are examined. In another set of experiments we investigate the properties of bosons confined to (quasi) one dimension in our magnetic waveguide. When the atom-atom repulsive interaction becomes much larger than the kinetic energy, bosons confined in one dimension can enter a new state of matter, the Tonks-Girardeau gas, in which they behave like non-interacting fermions. However, the bosons can still occupy the same momentum state and therefore the gas cannot be fully described by either Bose-Einstein or Fermi-Dirac statistics. This transition has been observed in optical lattices but not in magnetic atom chip waveguides. We discuss the conditions for obtaining a Tonks-Girardeau gas with 87Rb atoms in our atom chip waveguide as well as a novel signature for observing the transition in our system.

Anthony F. J. Levi

Murray T. Batchelor

The remarkable exact solution of 1D interacting fermions heralded a new era in the study of quantum many-body problems. The mathematical structure of the underlying Yang-Baxter equation led to profound advances in other fields. Recently there has been a significant revival of interest in 1D quantum many-body problems due to the striking and ongoing experimental developments in the study of cold quantum matter. In particular, through the trapping and cooling of interacting systems of atomic bosons and fermions in low dimensions. There is, e.g., already rather spectacular agreement between theory and experiment for 1D interacting bosons. This includes an experimental test of Yang-Yang thermodynamics for bosons on a chip...