Phase of scattering electron waves in quantum systems

D. C. Glattli

T. Sugiyama

Phase transitions of a quasi-one-dimensional Fermi gas are studied by the use of the renormalization group method for the fermion system without the bosonization. Intrachain backward and forward scatterings, pair electron hopping between different chains and exchange scattering of electrons in different chains are taken account of. Pair electron hopping gives rise to the singlet and triplet superconductor phase transitions. Electron exchange scattering gives rise to the spin density wave and charge density wave transitions. Calculation is made by the use of the one-dimensional dispersion. Following Menyhárd's method (Ref. 1) for the model with interchain backward scattering only, the change of the fluctuation from the one-dimensional region to the three-dimensional region is described. The transition temperatures are given by the bare couplings at high temperatures.

R.C. Liu, Y. Yamamoto

A partitioned system of fermions is mathematically equivalent to an assembly of two-level atoms described by spin operators. A number-phase uncertainty relation can therefore be derived to describe the noise properties of divided electrons. We examine both the number (or electron flux) and phase (or electron wave phase) decorrelation introduced by electron branching in mesoscopic circuits. Initially Poissonian, this electron number partition noise is increasingly suppressed by inelastic scattering in the transition from ballistic to dissipative electron division. Graphical results from our model show a trend from a coherent spin state in the ballistic regime toward a number-squeezed spin state in the dissipative regime, even when detrimental elastic scattering is present.

Akira Tonomura

David Thomas Pegg, Stephen Mark Barnett, Joan A. Vaccaro

Yu. E. Lozovik, I. V. Ovchinnikov, Vladimir A. Sharapov

A theoretical study is reported of stimulated light scattering, including wave-vector reversal and anomalous transmission, by a coherent phase in electron-hole (e-h) systems of low and high charge-carrier density. For these two cases the coherent phase is taken to be a Bose-Einstein condensate of excitons or a BCS-like state of e-h pairs, respectively. The scattering mechanism is laser-induced coherent recombination of two excitons or two coherent e-h pairs, respectively. The e-h system is assumed to exist within a GaAs/AlGaAs double quantum well or bulk GaAs. The emission rate of two photons with antiparallel momenta is estimated. Multiphoton emission due to multiexciton coherent recombination is covered. Methods for detecting the effects predicted are proposed.