642 research outputs found
Generating entanglement of photon-number states with coherent light via cross-Kerr nonlinearity
We propose a scheme for generating entangled states of light fields. This
scheme only requires the cross-Kerr nonlinear interaction between coherent
light-beams, followed by a homodyne detection. Therefore, this scheme is within
the reach of current technology. We study in detail the generation of the
entangled states between two modes, and that among three modes. In addition to
the Bell states between two modes and the W states among three modes, we find
plentiful new kinds of entangled states. Finally, the scheme can be extend to
generate the entangled states among more than three modes.Comment: 2 figure
Probabilistic teleportation and entanglement matching
Teleportation may be taken as sending and extracting quantum information
through quantum channels. In this report, it is shown that to get the maximal
probability of exact teleportation through partially entangled quantum
channels, the sender (Alice) need only to operate a measurement which satisfy
an ``entanglement matching'' to this channel. An optimal strategy is also
provided for the receiver (Bob) to extract the quantum information by adopting
general evolutions.Comment: 3.5 pages, No figure
Physical implementation of entangling quantum measurements
We clarify the microscopic structure of the entangling quantum measurement
superoperators and examine their possible physical realization in a simple
three-qubit model, which implements the entangling quantum measurement with an
arbitrary degree of entanglement.Comment: 6 pages, 2 fihure
Quantum teleportation of EPR pair by three-particle entanglement
Teleportation of an EPR pair using triplet in state of the
Horne-Greenberger-Zeilinger form to two receivers is considered. It needs a
three-particle basis for joint measurement. By contrast the one qubit
teleportation the required basis is not maximally entangled. It consists of the
states corresponding to the maximally entanglement of two particles only. Using
outcomes of measurement both receivers can recover an unknown EPR state however
one of them can not do it separately. Teleportation of the N-particle
entanglement is discussed.Comment: 7 pages, LaTeX, 3 figure
Quantum Teleportation with a Complete Bell State Measurement
We report a quantum teleportation experiment in which nonlinear interactions
are used for the Bell state measurements. The experimental results demonstrate
the working principle of irreversibly teleporting an unknown arbitrary quantum
state from one system to another distant system by disassembling into and then
later reconstructing from purely classical information and nonclassical EPR
correlations. The distinct feature of this experiment is that \emph{all} four
Bell states can be distinguished in the Bell state measurement. Teleportation
of a quantum state can thus occur with certainty in principle.Comment: 4 pages, submitted to PR
Quantum interference with photon pairs created in spatially separated sources
We report on a quantum interference experiment to probe the coherence between
two photons coming from non degenerate photon pairs at telecom wavelength
created in spatially separated sources. The two photons are mixed on a beam
splitter and we observe a reduction of up to 84% in the coincidence count rate
when the photons are made indistinguishable. This experiment constitutes an
important step towards the realization of quantum teleportation and
entanglement swapping with independent sources.Comment: 5 pages, 2 figures, changes according to referee's comments,
discussions partly rewritte
Pulse-driven near-resonant quantum adiabatic dynamics: lifting of quasi-degeneracy
We study the quantum dynamics of a two-level system driven by a pulse that
starts near-resonant for small amplitudes, yielding nonadiabatic evolution, and
induces an adiabatic evolution for larger amplitudes. This problem is analyzed
in terms of lifting of degeneracy for rising amplitudes. It is solved exactly
for the case of linear and exponential rising. Approximate solutions are given
in the case of power law rising. This allows us to determine approximative
formulas for the lineshape of resonant excitation by various forms of pulses
such as truncated trig-pulses. We also analyze and explain the various
superpositions of states that can be obtained by the Half Stark Chirped Rapid
Adiabatic Passage (Half-SCRAP) process.Comment: 21 pages, 12 figure
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