4 research outputs found
Continuous-Variable Quantum Teleportation with a Conventional Laser
We give a description of balanced homodyne detection (BHD) using a
conventional laser as a local oscillator (LO), where the laser field outside
the cavity is a mixed state whose phase is completely unknown. Our description
is based on the standard interpretation of the quantum theory for measurement,
and accords with the experimental result in the squeezed state generation
scheme. We apply our description of BHD to continuous-variable quantum
teleportation (CVQT) with a conventional laser to analyze the CVQT experiment
[A. Furusawa et al., Science 282, 706 (1998)], whose validity has been
questioned on the ground of intrinsic phase indeterminacy of the laser field
[T. Rudolph and B.C. Sanders, Phys. Rev. Lett. 87, 077903 (2001)]. We show that
CVQT with a laser is valid only if the unknown phase of the laser field is
shared among sender's LOs, the EPR state, and receiver's LO. The CVQT
experiment is considered valid with the aid of an optical path other than the
EPR channel and a classical channel, directly linking between a sender and a
receiver. We also propose a method to probabilistically generate a strongly
phase-correlated quantum state via continuous measurement of independent
lasers, which is applicable to realizing CVQT without the additional optical
path.Comment: 5 pages, 2 figure