1,495 research outputs found
Robust Quantum Communication Using A Polarization-Entangled Photon Pair
Noise and imperfection of realistic devices are major obstacles for
implementing quantum cryptography. In particular birefringence in optical
fibers leads to decoherence of qubits encoded in polarization of photon. We
show how to overcome this problem by doing single qubit quantum communication
without a shared spatial reference frame and precise timing. Quantum
information will be encoded in pair of photons using ``tag'' operations which
corresponds to the time delay of one of the polarization modes. This method is
robust against the phase instability of the interferometers despite the use of
time-bins. Moreover synchronized clocks are not required in the ideal situation
no photon loss case as they are only necessary to label the different encoded
qubits.Comment: 4 pages, 2 figure
Synthetic Helical Liquids with Ultracold Atoms in Optical Lattices
We discuss a platform for the synthetic realization of key physical
properties of helical Tomonaga Luttinger liquids (HTLLs) with ultracold
fermionic atoms in one-dimensional optical lattices. The HTLL is a strongly
correlated metallic state where spin polarization and propagation direction of
the itinerant particles are locked to each other. We propose an unconventional
one-dimensional Fermi-Hubbard model which, at quarter filling, resembles the
HTLL in the long wavelength limit, as we demonstrate with a combination of
analytical (bosonization) and numerical (density matrix renormalization group)
methods. An experimentally feasible scheme is provided for the realization of
this model with ultracold fermionic atoms in optical lattices. Finally, we
discuss how the robustness of the HTLL against back-scattering and
imperfections, well known from its realization at the edge of two-dimensional
topological insulators, is reflected in the synthetic one-dimensional scenario
proposed here
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