1,549 research outputs found
Continuous variable teleportation of single photon states
The properties of continuous variable teleportation of single photon states
are investigated. The output state is different from the input state due to the
non-maximal entanglement in the EPR beams. The photon statistics of the
teleportation output are determined and the correlation between the field
information beta obtained in the teleportation process and the change in photon
number is discussed. The results of the output photon statistics are applied to
the transmission of a qbit encoded in the polarization of a single photon.Comment: 14 pages, including 6 figure
Cavity QED with high-Q whispering gallery modes
We report measurements of cavity-QED effects for the radiative coupling of atoms in a dilute vapor to the external evanescent field of a whispering-gallery mode (WGM) in a fused silica microsphere. The high Q (5 x 10^(7)), small mode volume (10^(-8) cm^(3)), and unusual symmetry of the microcavity evanescent field enable velocity-selective interactions between fields with photon number of order unity in the WGM and (N) over bar(T) similar to 1 atoms in the surrounding vapor
Minimum cbits for remote preperation and measurement of a qubit
We show that a qubit chosen from equatorial or polar great circles on a Bloch
spehere can be remotely prepared with one cbit from Alice to Bob if they share
one ebit of entanglement. Also we show that any single particle measurement on
an arbitrary qubit can be remotely simulated with one ebit of shared
entanglement and communication of one cbit.Comment: Latex, 7 pages, minor changes, references adde
Classical Teleportation of a Quantum Bit
Classical teleportation is defined as a scenario where the sender is given
the classical description of an arbitrary quantum state while the receiver
simulates any measurement on it. This scenario is shown to be achievable by
transmitting only a few classical bits if the sender and receiver initially
share local hidden variables. Specifically, a communication of 2.19 bits is
sufficient on average for the classical teleportation of a qubit, when
restricted to von Neumann measurements. The generalization to
positive-operator-valued measurements is also discussed.Comment: 4 pages, RevTe
Quantum Teleportation Between Distant Matter Qubits
Quantum teleportation is the faithful transfer of quantum states between
systems, relying on the prior establishment of entanglement and using only
classical communication during the transmission. We report teleportation of
quantum information between atomic quantum memories separated by about 1 meter.
A quantum bit stored in a single trapped ytterbium ion (Yb+) is teleported to a
second Yb+ atom with an average fidelity of 90% over a replete set of states.
The teleportation protocol is based on the heralded entanglement of the atoms
through interference and detection of photons emitted from each atom and guided
through optical fibers. This scheme may be used for scalable quantum
computation and quantum communication.Comment: 5 pages, 4 figure
Experimental verification of a fully inseparable tripartite continuous-variable state
A continuous-variable tripartite entangled state is experimentally generated
by combining three independent squeezed vacuum states and the variances of its
relative positions and total momentum are measured. We show that the measured
values violate the separability criteria based on the sum of these quantities
and prove the full inseparability of the generated state.Comment: 5 pages, 4 figure
Discrete formulation of teleportation of continuous variables
Teleportation of continuous variables can be described in two different ways,
one in terms of Wigner functions, the other in terms of discrete basis states.
The latter formulation provides the connection between the theory of
teleportation of continuous degrees of freedom of a light field and the
standard description of teleportation of discrete variables.Comment: Important reference included: L. Vaidman, Phys Rev A 49, 1473 (1994
The Quantum State of an Ideal Propagating Laser Field
We give a quantum information-theoretic description of an ideal propagating
CW laser field and reinterpret typical quantum-optical experiments in light of
this. In particular we show that contrary to recent claims [T. Rudolph and B.
C. Sanders, Phys. Rev. Lett. 87, 077903 (2001)], a conventional laser can be
used for quantum teleportation with continuous variables and for generating
continuous-variable entanglement. Optical coherence is not required, but phase
coherence is. We also show that coherent states play a priveleged role in the
description of laser light.Comment: 4 pages RevTeX, to appear in PRL. For an extended version see
quant-ph/011115
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
Electron Entanglement via a Quantum Dot
This Letter presents a method of electron entanglement generation. The system
under consideration is a single-level quantum dot with one input and two output
leads. The leads are arranged such that the dot is empty, single electron
tunneling is suppressed by energy conservation, and two-electron virtual
co-tunneling is allowed. This yields a pure, non-local spin-singlet state at
the output leads. Coulomb interaction is the nonlinearity essential for
entanglement generation, and, in its absence, the singlet state vanishes. This
type of electron entanglement is a four-wave mixing process analogous to the
photon entanglement generated by a Chi-3 parametric amplifier.Comment: 4 page
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