8,791 research outputs found
Euler solution of multiblade rotor flow
A numerical method for solving the Euler equations for multiblade rotors has been developed and some preliminary results reported. The numerical scheme is a combination of several recent methods and algorithm improvements, adapted to the particular requirements of rotor-body interactions. A cylindrical basic grid has been used to study conventional multiblade helicopter rotors. Test calculations have been made for two- and six-blade rotors in hover and for a two-blade rotor in forward flight, under transonic tip conditions but without lift. The results show good agreement with experimental data
Atomic Entanglement vs Photonic Visibility for Quantum Criticality of Hybrid System
To characterize the novel quantum phase transition for a hybrid system
consisting of an array of coupled cavities and two-level atoms doped in each
cavity, we study the atomic entanglement and photonic visibility in comparison
with the quantum fluctuation of total excitations. Analytical and numerical
simulation results show the happen of quantum critical phenomenon similar to
the Mott insulator to superfluid transition. Here, the contour lines
respectively representing the atomic entanglement, photonic visibility and
excitation variance in the phase diagram are consistent in the vicinity of the
non-analytic locus of atomic concurrences.Comment: 4 pages, 2 figure
Fully gapped superconducting state in Au2Pb: a natural candidate for topological superconductor
We measured the ultra-low-temperature specific heat and thermal conductivity
of AuPb single crystal, a possible three-dimensional Dirac semimetal with a
superconducting transition temperature 1.05 K. The electronic
specific heat can be fitted by a two-band s-wave model, which gives the gap
amplitudes (0)/ = 1.38 and (0)/ = 5.25.
From the thermal conductivity measurements, a negligible residual linear term
in zero field and a slow field dependence of at low
field are obtained. These results suggest that AuPb has a fully gapped
superconducting state in the bulk, which is a necessary condition for
topological superconductor if AuPb is indeed one.Comment: 6 pages, 4 figure
On effects of regular S=1 dilution of S=1/2 antiferromagnetic Heisenberg chains by a quantum Monte Carlo simulation
The effects of regular S=1 dilution of S=1/2 isotropic antiferromagnetic
chain are investigated by the quantum Monte Carlo loop/cluster algorithm. Our
numerical results show that there are two kinds of ground-state phases which
alternate with the variation of concentration. When the effective spin
of a unit cell is half-integer, the ground state is ferrimagnetic with gapless
energy spectrum and the magnetism becomes weaker with decreasing of the
concentration . While it is integer, a non-magnetic ground state
with gaped spectrum emerges and the gap gradually becomes narrowed as fitted by
a relation of .Comment: 6 pages, 9 figure
Hysteresis in the quantum Hall regimes in electron double quantum well structures
We present in this paper experimental results on the transport hysteresis in
electron double quantum well structures. Exploring the measurement technique of
fixing the magnetic field and sweeping a front gate voltage (Vg), we are able
to study the hysteresis by varying the top layer Landau level fillings while
maintaining a relatively constant filling factor in the bottom layer, allowing
us to tackle the question of the sign of Rxx(up)-Rxx(down), where Rxx(up) is
the magnetoresistance when Vg is swept up and Rxx(down) when Vg swept down.
Furthermore, we observe that hysteresis is generally stronger in the even
integer quantum Hall effect (IQHE) regime than in the odd-IQHE regime. This, we
argue, is due to a larger energy gap for an even-IQHE state, determined by the
Landau level separation, than that for an odd-IQHE state, determined by the
Zeeman splitting
Universal and original-preserving quantum copying is impossible
We show that an arbitrary quantum state cannot be universally 1 → 2 copied keeping the original copy unchanged. Indeed, the density operator of the additional copy after the copying transformation is nothing but the scale product of the identity matrix with factor 1/2, which involves no information of the original state. © 2002 Elsevier Science B.V. All rights reserved
Peierls distorted chain as a quantum data bus for quantum state transfer
We systematically study the transfer of quantum state of electron spin as the
flying qubit along a half-filled Peierls distorted tight-binding chain
described by the Su-Schrieffer-Heeger (SSH) model, which behaves as a quantum
data bus. This enables a novel physical mechanism for quantum communication
with always-on interaction: the effective hopping of the spin carrier between
sites and connected to two sites in this SSH chain can be induced by
the quasi-excitations of the SSH model. As we prove, it is the Peierls energy
gap of the SSH quasi-excitations that plays a crucial role to protect the
robustness of the quantum state transfer process. Moreover, our observation
also indicates that such a scheme can also be employed to explore the intrinsic
property of the quantum system.Comment: 10 pages, 6 figure
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