Magneto-Acoustic Spectroscopy in Superfluid 3He-B

We have used the recently discovered acoustic Faraday effect in superfluid 3He to perform high resolution spectroscopy of an excited state of the superfluid condensate. With acoustic cavity interferometry we measure the rotation of the plane of polarization of a transverse sound wave propagating in the direction of magnetic field from which we determine the Zeeman energy of the excited state. We interpret the Lande g-factor, combined with the zero-field energies of the state, using the theory of Sauls and Serene to calculate the strength of f -wave interactions in 3He.Comment: 4 pages, 5 figures, submitted to PRL, Aug 30th, 200

Hartree-Fock calculations of a finite inhomogeneous quantum wire

We use the Hartree-Fock method to study an interacting one-dimensional electron system on a finite wire, partially depleted at the center by a smooth potential barrier. A uniform one-Tesla Zeeman field is applied throughout the system. We find that with the increase in the potential barrier, the low density electrons under it go from a non-magnetic state to an antiferromagnetic state, and then to a state with a well-localized spin-aligned region isolated by two antiferromagnetic regions from the high density leads. At this final stage, in response to a continuously increasing barrier potential, the system undergoes a series of abrupt density changes, corresponding to the successive expulsion of a single electron from the spin-aligned region under the barrier. Motivated by the recent momentum-resolved tunneling experiments in a parallel wire geometry, we also compute the momentum resolved tunneling matrix elements. Our calculations suggest that the eigenstates being expelled are spatially localized, consistent with the experimental observations. However, additional mechanisms are needed to account for the experimentally observed large spectral weight at near $k=0$ in the tunneling matrix elements.Comment: 10 pages, 14 figure

Nonlinear field-dependence and f-wave interactions in superfluid 3He

We present results of transverse acoustics studies in superfluid ^{3}He-B at fields up to 0.11 T. Using acoustic cavity interferometry, we observe the Acoustic Faraday Effect for a transverse sound wave propagating along the magnetic field, and we measure Faraday rotations of the polarization as large as 1710^{\circ}. We use these results to determine the Zeeman splitting of the Imaginary Squashing mode, an order parameter collective mode with total angular momentum J=2. We show that the pairing interaction in the f-wave channel is attractive at a pressure of P=6 bar. We also report nonlinear field dependence of the Faraday rotation at frequencies substantially above the mode frequency not accounted for in the theory of the transverse acoustic dispersion relation formulated for frequencies near the mode. Consequently, we have identified the region of validity of the theory allowing us to make corrections to the analysis of Faraday rotation experiments performed in earlier work.Comment: 7 pages, 5 figure