13 research outputs found
Topological Order in Spin Liquids with Chirality
We use the Kalmeyer-Laughlin Chiral Spin Liquid as building block to construct a hierarchy of higher-spin spin liquids and determine numerically their topological properties.
We compute the entanglement spectra of some of these liquids as well as of ground states of critically frustrated quantum magnets. From the comparison, we find preliminary evidence for a topological phase transition in these systems
Photonic architecture for scalable quantum information processing in NV-diamond
Physics and information are intimately connected, and the ultimate
information processing devices will be those that harness the principles of
quantum mechanics. Many physical systems have been identified as candidates for
quantum information processing, but none of them are immune from errors. The
challenge remains to find a path from the experiments of today to a reliable
and scalable quantum computer. Here, we develop an architecture based on a
simple module comprising an optical cavity containing a single
negatively-charged nitrogen vacancy centre in diamond. Modules are connected by
photons propagating in a fiber-optical network and collectively used to
generate a topological cluster state, a robust substrate for quantum
information processing. In principle, all processes in the architecture can be
deterministic, but current limitations lead to processes that are probabilistic
but heralded. We find that the architecture enables large-scale quantum
information processing with existing technology.Comment: 24 pages, 14 Figures. Comment welcom
Geometric phases in semiconductor spin qubits: Manipulations and decoherence
We describe the effect of geometric phases induced by either classical or
quantum electric fields acting on single electron spins in quantum dots in the
presence of spin-orbit coupling. On one hand, applied electric fields can be
used to control the geometric phases, which allows performing quantum coherent
spin manipulations without using high-frequency magnetic fields. On the other
hand, fluctuating fields induce random geometric phases that lead to spin
relaxation and dephasing, thus limiting the use of such spins as qubits. We
estimate the decay rates due to piezoelectric phonons and conduction electrons
in the circuit, both representing dominant electric noise sources with
characteristically differing power spectra.Comment: 17 pages, 8 figures, published versio