The measurements of the time dependent current fluctuations (noise) in mesoscopic devices represent a great tool to investigate electron correlations. This tool can give access to information, which is not contained in usual conductance measurements, such a s the effective charge of carriers or to distinguish the classical and quantum nature of chaotic scattering in cavities. It can also be used to test particle statistics. The fermionic/bosonic character leads to anti-bunching/bunching of the particles.
The antibunching of the fermions is a consequence of the Pauli principle. If a fermionic beam splits into two partial ones, the fluctuations in the two partial beams are anticorrelated. A few years ago the host institute realized a fermionic analogon of the single-source Hanbury-Brown and amp;Twiss (HBT) experiment demonstrating that electrons anti-bunch as a consequence of their fermionic nature. However, bunching of electrons is possible, if for example electrons are paired in a spin singlet state, as realize d in conventional superconductors. This pairing would lead to positive correlations.
The goal of this project is to `search for positive current cross-correlations due to the entanglement of electrons. We will focus on correlation originated from two different types of entanglement in multiterminal semiconducting nanostructures: Spin entanglement will be studied in superconductor-normal hybrid structures; a super-conducting (Nb) electrode will be used as an emitter of correlated electron pairs into a Y-shaped beam splitter constructed in 2-dimensional electron gas (2DEG). Entanglement based on the orbital degree of freedom will be probed in a two-source HBT-interferometer, which will be fabricated in 2DEG operating in the quantum Hall regime.
These experiments help to understand and control the entangled mobile electrons, which is fundamental for the new field of quantum computation and communication in solid state environment.
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