We report an experimental realization of an atomic vapor quantum memory for the photonic polarization qubit.
The performance of the quantum memory for the polarization qubit, realized with electromagnetically-induced
transparency in two spatially separated ensembles of warm Rubidium atoms in a single vapor cell, has been
characterized with quantum process tomography. The process fidelity better than 0.91 for up to 16 μs of storage
time has been achieved.
We report an experimental demonstration of slowed propagation and storage and retrieval of thermal light using
the effect of electromagnetically-induced transparency (EIT) in the Λ-type system of the D1 transition of <sup>85</sup>Rb
atom. The slowed-propagation of the probe thermal light beam through an EIT medium is observed by measuring
the second-order correlation function of the light field using the Hanbury-Brown-Twiss interferometer. We also
demonstrate the storage and retrieval of thermal light beam in the EIT medium. The direct measurement of the
photon number statistics of the retrieved light field shows that the photon number statistics is preserved during
the storage and retrieval process.
We report an experimental implementation of quantum random number generator based on the photon-number-path
entangled state. The photon-number-path entangled state is prepared by means of two-photon Hong-Ou-Mandel
quantum interference at a beam splitter. The randomness in our scheme is of truly quantum mechanical origin
as it comes from the projection measurement of the entangled two-photon state. The generated bit sequences
satisfy the standard randomness test.
A pair of optical pulses traveling through two dispersive media will become broadened and, as a result, the degree
of coincidence between the optical pulses will be reduced. For a pair of entangled photons, however, nonlocal
dispersion cancellation in which the dispersion experienced by one photon cancels the dispersion experienced
by the other photon is possible. In this paper, we report an experimental demonstration of nonlocal dispersion
cancellation using entangled photons. The degree of two-photon coincidence is shown to increase beyond
the limit attainable without entanglement. Our results have important applications in fiber-based quantum
communication and quantum metrology.