Phase conjugation of a quantum-degenerate atomic fermion beam

We discuss the possibility of phase conjugation of an atomic Fermi field via nonlinear wave mixing in an ultracold gas. It is shown that for a beam of fermions incident on an atomic phase-conjugate mirror, a time-reversed backward propagating fermionic beam is generated similar to the case in nonlinear optics. By adopting an operational definition of the phase, we show that it is possible to infer the presence of the phase-conjugate field by the loss of the interference pattern in an atomic interferometer.     

Eliminating the mean-field shift in two-component bose-einstein condensates

We demonstrate that the nonlinear mean-field shift in a multicomponent Bose-Einstein condensate may be eliminated by controlling the two-body interaction coefficients. This modification can be achieved by engineering the environment of the condensate. We consider the case of a two-component condensate in a quasi-one-dimensional atomic waveguide, achieving modification of the atom-atom interactions by varying the transverse wave functions of the components. Eliminating the density-dependent phase shift represents a promising potential application for multicomponent condensates in atom interferometry and precision measurements.     

Macroscopic spin tunneling and quantum critical behavior of a condensate in a double-well potential

In a previous work [H. Pu, W. Zhang, and P. Meystre, Phys. Rev. Lett. 87, 140405 (2001)]], we have shown that a spinor condensate confined in a periodic or double-well potential exhibits ferromagnetic behavior due to the magnetic dipole-dipole interactions between different wells, and in the absence of external magnetic field, the ground state has a twofold degeneracy. In this work, we demonstrate the possibility of observing macroscopic quantum spin tunneling between these two degenerate states and show how the tunneling rate critically depends on the strength of the transverse field.     

Diffraction of a superfluid fermi gas by an atomic grating

An atomic grating generated by a pulsed standing-wave laser field is proposed to manipulate the superfluid state in a quantum degenerate gas of fermionic atoms. We show that in the presence of atomic Cooper pairs, the density oscillations of the gas caused by the atomic grating exhibit a much longer coherence time than that in the normal Fermi gas. Our result indicates that the technique of a pulsed atomic grating is a potential candidate to detect the atomic superfluid state in a quantum degenerate Fermi gas.     

Squeezed states in the Jaynes-Cummings model

It is shown that squeezed states of the electromagnetic field are obtained in the Jaynes-Cummings model of an atomic transition coupled to a single mode, quantized electromagnetic field.     

Directionally asymmetrical bistability in a symmetrically pumped nonlinear ring interferometer

We consider a nonlinear ring resonator pumped symmetrically by two beams of equal intensities and opposite directions. We show that this system is characterized by a new directionally asymmetrical regime of multistability. This is due to the non-reciprocity of propagation of the counterpropagating waves in the resonator produced by a nonlinear index grating.