3,621 research outputs found
Low-noise conditional operation of singlet-triplet coupled quantum dot qubits
We theoretically study the influence of charge noise on a controlled phase
gate, implemented using two proximal double quantum dots coupled
electrostatically. Using the configuration interaction method, we present a
full description of the conditional control scheme and quantitatively calculate
the gate error arising from charge fluctuations. Our key finding is that the
existence of noise-immune sweet spots depends on not only the energy detuning
but also the device geometry. The conditions for sweet spots with minimal
charge noise are predicted analytically and verified numerically. Going beyond
the simple sweet-spot concept we demonstrate the existence of other optimal
situations for fast and low-noise singlet-triplet two-qubit gates.Comment: 4 pages, 4 figure
Productions of heavy charged leptons via gluon fusion at LHC: A revisit
Heavy charged lepton productions via gluon fusion at the LHC are revisited.
Full loop calculations are adopted with an updated parton distribution function
and electroweak data. Including contribution from new generation quarks in the
loop, pair production of the sequential heavy lepton via gluon fusion at the
LHC dominates over that via the Drell-Yan mechanism in some heavy lepton mass
range. Exotic lepton single production of vector-like lepton extended models is
also calculated. In the later case, the gluon fusion mechanism via the Higgs
exchange is emphasized. Our numerical results for both pair and single
production of heavy leptons are smaller than previous studies especially for a
large heavy lepton mass as a result of full loop calculation and due to the
mixing angles.Comment: 18 pages, 7 figures; (v2) typos corrected, references adde
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