188,128 research outputs found
A remark on the Hard Lefschetz Theorem for K\"ahler orbifolds
We give a proof of the hard Lefschetz theorem for orbifolds that does not
involve intersection homology. This answers a question of Fulton. We use a
foliated version of the hard Lefschetz theorem due to El Kacimi
Thermal Entanglement in Ferrimagnetic Chains
A formula to evaluate the entanglement in an one-dimensional ferrimagnetic
system is derived. Based on the formula, we find that the thermal entanglement
in a small size spin-1/2 and spin-s ferrimagnetic chain is rather robust
against temperature, and the threshold temperature may be arbitrarily high when
s is sufficiently large. This intriguing result answers unambiguously a
fundamental question: ``can entanglement and quantum behavior in physical
systems survive at arbitrary high temperatures?"Comment: 4 pages, 3 figure
Single-photon transport in a one dimentional waveguide coupling to a hybrid atom-optomechanical system
We explore theoretically the single-photon transport in a single-mode
waveguide that is coupled to a hybrid atom-optomechanical system in a strong
optomechanical coupling regime. Using a full quantum real-space approach,
transmission and reflection coefficients of the propagating single-photon in
the waveguide are ob- tained. The influences of atom-cavity detuning and the
dissipation of atom on the transport are also studied. Intriguingly, the
obtained spectral features can reveal the strong light-matter interaction in
this hybrid system.Comment: 7pages, 8figure
Operator fidelity susceptibility: an indicator of quantum criticality
We introduce the operator fidelity and propose to use its susceptibility for
characterizing the sensitivity of quantum systems to perturbations. Two typical
models are addressed: one is the transverse Ising model exhibiting a quantum
phase transition, and the other is the one dimensional Heisenberg spin chain
with next-nearest-neighbor interactions, which has the degeneracy. It is
revealed that the operator fidelity susceptibility is a good indicator of
quantum criticality regardless of the system degeneracy.Comment: Four pages, two figure
Quantum storage and information transfer with superconducting qubits
We design theoretically a new device to realize the general quantum storage
based on dcSQUID charge qubits. The distinct advantages of our scheme are
analyzed in comparison with existing storage scenarios. More arrestingly, the
controllable XY-model spin interaction has been realized for the first time in
superconducting qubits, which may have more potential applications besides
those in quantum information processing. The experimental feasibility is also
elaborated.Comment: 4 pages, 2 figure
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