Some Research Activities

During her PhD in Orsay (defended in 96) under the direction of the late H. J. Schulz, Ines Safi has predicted the charge fractionalization in quantum wires, by introducing chiral plasmonic density operators and proposing uni-directional injection of electrons. This study was further investigated by K. V. Pham and collaborators two years later. Attempts were recently performed to test experimentally the phenomena by the group of A. Yacoby in Harvard. Nevertheless, it holds in an infinite wire, and can be modified by connection to charge reservoirs. In order to take into account the latter, Inès Safi proposed an original model, simultanously with D. Maslov (his paper was submitted one week after!). The prediction of DC conductance was confirmed very soon by the group of Tarucha in Japan, and by others later on. This gave rise to a fruitful debate, and the model was finally recognized as the most suited to study quantum transport in quantum wires and carbon nanotubes, as confirmed by other approaches. In particular, Inès Safi has discovered a new crucial phenomena, a momentum-conserving reflection of an electron impinging on an interacting wire, which can also be extended to edge states in the fractional quantum Hall regime.During her postdoctoral period in CEA (96-98, Orme des Merisiers, France), revisiting the results of Kane and Fisher close to resonance, Inès Safi has explained some of the features of the experimental observation of fractional charge through shot noise measurement by the group of C. Glattli, cited in the Nobel lecture of Laughlin. After getting a permanent position in CNRS in 1998, she moved to CPT in Marseille where she has proposed for the first time to use noise correlations to detect fractional statistics, through a three-terminal set-up (coll. T. Martin). She has also started to develop a general Keldysh approach to treat both DC and AC current and finite-frequency noise in chiral and non-chiral systems, and for general Hamiltonians depending on both conjugate bosonic fields, a situation not treated before. This field has been pursued by the group of Marseille after she returned to LPS in Orsay (in 2000). She has been an expert in out-of equilibrium transport in one dimensional systems, studying non-linear current and high-frequency noise in those systems, in particular with her two previous post-doctorates Bjoern Trauzettel and Cristina Bena (colls. F. Dolcini, H. Grabert and A. Crépieux).

Inès Safi has worked on coherent conductors embedded in an ohmic circuit, and was able for the first time to treat the case of a good transmitting channel in series with an arbitrary resistance, yielding exact predictions not only for current average, its fluctuations (noise), but also higher cumulants (coll. H. Saleur).

Those works give a very interesting possibility to distinguish the role of intrinsic interactions from that of an external resistance of the circuit.

Inès Safi est chargée de recherche au CNRS en physique théorique de la matière condensée à Orsay.

Inès Safi (safi@lps.u-psud.fr), Laboratoire de Physique des Solides, Université Paris-Sud, Orsay (France)