34,658 research outputs found
Majorana fermions in s-wave noncentrosymmetric superconductor with Rashba and Dresselhaus (110) spin-orbit couplings
The asymmetric spin-orbit (SO) interactions play a crucial role in realizing
topological phases in noncentrosymmetric superconductor (NCS).We investigate
the edge states and the vortex core states in s-wave NCS with Rashba and
Dresselhaus (110) SO couplings by both numerical and analytical methods. In
particular, we demonstrate that there exists a novel semimetal phase
characterized by the flat Andreev bound states in the phase diagram of the
s-wave Dresselhaus NCS which supports the emergence of Majorana fermion (MF).
The flat dispersion implies a peak in the density of states which has a clear
experimental signature in the tunneling conductance measurements and the MFs
proposed here should be experimentally detectable
Realizations of the -Heisenberg and -Virasoro Algebras
We give field theoretic realizations of both the -Heisenberg and the
-Virasoro algebra. In particular, we obtain the operator product expansions
among the current and the energy momentum tensor obtained using the Sugawara
construction.Comment: 9 page
Kinematic approach to the mixed state geometric phase in nonunitary evolution
A kinematic approach to the geometric phase for mixed quantal states in
nonunitary evolution is proposed. This phase is manifestly gauge invariant and
can be experimentally tested in interferometry. It leads to well-known results
when the evolution is unitary.Comment: Minor changes; journal reference adde
High efficiency tomographic reconstruction of quantum states by quantum nondemolition measurements
We propose a high efficiency tomographic scheme to reconstruct an unknown
quantum state of the qubits by using a series of quantum nondemolition (QND)
measurements. The proposed QND measurements of the qubits are implemented by
probing the the stationary transmissions of the dispersively-coupled resonator.
It is shown that only one kind of QND measurements is sufficient to determine
all the diagonal elements of the density matrix of the detected quantum state.
The remaining non-diagonal elements of the density matrix can be determined by
other spectral measurements by beforehand transferring them to the diagonal
locations using a series of unitary operations. Compared with the pervious
tomographic reconstructions based on the usual destructively projective (DP)
measurements (wherein one kind of such measurements could only determine one
diagonal element of the density matrix), the present approach exhibits
significantly high efficiency for N-qubit (N > 1). Specifically, our generic
proposal is demonstrated by the experimental circuit-quantumelectrodynamics
(circuit-QED) systems with a few Josephson charge qubits.Comment: 9pages,4figure
Achieving diffraction-limited performance on the Berkeley MET5
The Berkeley MET5, funded by EUREKA, is a 0.5-NA EUV projection lithography tool located at the Advanced Light Source at Berkeley National Lab. Wavefront measurements of the MET5 optic have been performed using a custom in-situ lateral shearing interferometer suitable for high-NA interferometry. In this paper, we report on the most recent characterization of the MET5 optic demonstrating an RMS wavefront 0.31 nm, and discuss the specialized mask patterns, gratings, and illumination geometries that were employed to accommodate the many challenges associated with high-NA EUV interferometry
Experimental Quantum Cloning with Prior Partial Information
When prior partial information about a state to be cloned is available, it
can be cloned with a fidelity higher than that of universal quantum cloning. We
experimentally verify this intriguing relationship between the cloning fidelity
and the prior information by reporting the first experimental optimal quantum
state-dependent cloning, using nuclear magnetic resonance techniques. Our
experiments may further have important implications into many quantum
information processing protocols.Comment: 4 pages, 2 figure
Quantitative conditions do not guarantee the validity of the adiabatic approximation
In this letter, we point out that the widely used quantitative conditions in
the adiabatic theorem are insufficient in that they do not guarantee the
validity of the adiabatic approximation. We also reexamine the inconsistency
issue raised by Marzlin and Sanders (Phys. Rev. Lett. 93, 160408, 2004) and
elucidate the underlying cause.Comment: corrected typos. Eq. (32) is corrected. No other change
Hadronic decays of B involving a tensor meson through a transition
We re-analyze hadronic decays of B mesons to a pseudoscalar (P) and a tensor
meson (T), or a vector meson (V) and a tensor meson, through a
transition. We discuss possible large uncertainties to branching ratios (BR's)
of the relevant modes, mainly arising from uncertainties to the hadronic form
factors for the transition. The BR's and CP asymmetries for and VT decays are then calculated by using the form factors given in the
ISGW2 model (the improved version of the original Isgur-Scora-Grinstein-Wise
(ISGW) model). We find that the estimated BR's of many modes are increased by
an order of magnitude, compared to the previous results calculated within the
ISGW model.Comment: 22 pages, LaTex; minor clarifications included; to appear in Phys.
Rev.
Broadcasting Quantum Fisher Information
It is well known that classical information can be cloned, but non-orthogonal
quantum states cannot be cloned, and non-commuting quantum states cannot be
broadcast. We conceive a scenario in which the object we want to broadcast is
the statistical distinguishability, as quantified by quantum Fisher
information, about a signal parameter encoded in quantum states. We show that
quantum Fisher information cannot be cloned, whilst it might be broadcast even
when the input states are non-commuting. This situation interpolates between
cloning of classical information and no-broadcasting of quantum information,
and indicates a hybrid way of information broadcasting which is of particular
significance from both practical and theoretical perspectives.Comment: 5 pages. Improved version. Any comments is welcom
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