Imaging in Quantum Point Contacts

Suppression of shot noise in quantum point contacts in the "0.7 regime".

Experimental investigations of current shot noise in quantum point contacts show a reduction of the noise near the 0.7 anomaly. It is demonstrated that such a reduction naturally arises in a model proposed recently to explain the characteristics of the 0.7 anomaly in quantum point contacts in terms of a quasibound state, due to the emergence of two conducting channels. We calculate the shot noi...

Scanning gate imaging of quantum point contacts and the origin of the 0.7 anomaly

Quantum Mechanic Studies of Natural Bond Orbital & Stabilities of [CuCH2SiMe3]4Complexes With Different Halogens

The asymmetric unit of the title compound,  Contains two independent molecules. The Cu atoms are four coordinated in distorted tetrahedral configuration by two atoms from 5,5`-dimethyl-2,2`- bipyridine and two terminal atoms. In the Cuystal structure, inter molecular hydrogen bonds link the molecules. The are  contacts between the methyl groups and the pyridine and five member rings containing ...

Noise of Series Quantum Point Contacts

Shot noise of series quantum point contacts forming a sequence of cavities in a two dimensional electron gas are studied theoretically and experimentally. Noise in such a structure originates from local scattering at the point contacts as well as from chaotic motion of the electrons in the cavities. The observed shot noise allows to distinguish between noise of the point contacts and noise from...

Imaging electron motion in graphene

A cooled scanning probe microscope (SPM) is an ideal tool to image electronic motion in graphene: the SPM tip acts as a scanning gate, which interacts with the electron gas below. We introduce the technique using our group’s previous work on imaging electron flow from a quantum point contact in a GaAs 2DEG and tuning an InAs quantum dot in an InAs/InP nanowire. Carriers in graphene have very di...

Detection of spin polarization in quantum point contacts

We use spatial spin separation by a magnetic focusing technique to probe the polarization of quantum point contacts. The point contacts are fabricated from p-type GaAs/AlGaAs heterostructures. A finite polarization is measured in the low density regime, when the conductance of a point contact is tuned to <2e2/h. Polarization is stronger in samples with a well defined ‘0.7 structure’. (Some figu...