January 2013

Abstracts of the QSIT Lunch Seminar, January 10, 2013

Graphene Triple Dots

Dominik Bischoff, Nanophysics Group, ETH Zurich

Graphene is a single atom thick layer of carbon atoms. It was theoretically predicted that spin qubits in graphene should exhibit long coherence times due to low spin-orbit and hyperfine interactions. As a consequence, many researchers have fabricated graphene quantum dots. While much progress was already made,  many open questions remain to be solved in order to fabricate graphene devices suitable for quantum computation. In this talk we try to answer a few of these questions by presenting a detailed analysis of measurements on a bilayer graphene serial triple quantum dot.

Realizing a Deterministic Teleportation Protocol in Superconducting Circuits

Lars Steffen, Quantum Device Lab, ETH Zurich

Teleportation of a quantum state may be used for distributing entanglement between distant qubits in quantum communication and for realizing universal and fault-tolerant quantum computation. Previously, we have demonstrated the implementation of a teleportation protocol, up to the single-shot measurement step, with superconducting qubits coupled to a microwave resonator [1]. Using full quantum state tomography and calculating the projection of the measured density matrix onto the basis states of two qubits has allowed us to reconstruct the teleported state with an average output state fidelity of 86%. Since this experiment we have implemented single shot read-out which allows us to perform teleportation by post-selection. In ongoing experiments we attempt to implement feed-back to perform full deterministic quantum teleportation.

Reference:

[1] M. Baur, A. Fedorov, L. Steffen, S. Filipp, M.P. da Silva, and A. Wallraff, Phys. Rev. Lett. 108, 040502 (2012)