Electronic quantum transport in mesoscopic system | Department of Physics

Electronic quantum transport in mesoscopic system

We work in the field of electronic quantum transport in mesoscopic systems. Mesoscopic systems are intermediate to that of microscopic (atomic) and macroscopic systems where quantum coherence is observed. The goal of the research is towards building up of devices that finds use in quantum information processing (QIP). Two fundamental quantum phenomena are important to realize devices for QIP, they are non-locality and entanglement. Non-locality refers to the existence of quantum correlations in spatially separated parts of a quantum system. A fundamental route for the exploration of this phenomenon is the generation of Einstein-Podolsky-Rosen (EPR) pairs of quantum entangled objects. Such pairs of quantum entangled objects has already been tested for photons but not yet for massive particles, like electrons as it is extremely difficult to obtain entangled electrons because electrons are immersed in a macroscopic ground state- the Fermi Sea – which prevents the straightforward generation and splitting of entangled electron pairs. The challenge can be faced by, first using a superconducting material that consists of a Cooper pair spin-singlet state as its ground state and second, by using semiconductor quantum dots in Coulomb blockade regime connected to a superconductor that would force to split the spin-entangled electrons coming out of the superconductor, and thus we would have an on-demand generation of spin-entangled electrons. Such creation of non-local quantum-entangled states in solid state devices would be exploited for secure quantum communication, quantum teleportation and to perform Bell inequality tests- a direct proof of entanglement which has yet to be produced for fermionic particles. The non-locality and entanglement would be probed by a unique set-up that would measure noise cross-correlations, a technique that is very sensitive to measure quantum correlations. The devices would also be probed by conventional transport measurements where interesting physics would also be investigated at superconductor-quantum dot junctions, for example Andreev Bound States, Crossed Andreev Reflection and Elastic Cotunneling. A major part of the challenge involves careful preparation of samples which requires a cleanroom facility. Electron beam lithography, AFM, electron beam evaporator would be the commonly used instruments to fabricate the samples and make electrical contacts.