Teleportation and spin squeezing utilizing multimode entanglement of light with atoms

Abstract

We present a protocol for the teleportation of the quantum state of a pulse of light onto the collective spin state of an atomic ensemble. The entangled state of light and atoms employed as a resource in this protocol is created by probing the collective atomic spin, Larmor precessing in an external magnetic field, off resonantly with a coherent pulse of light. We take here for the first time full account of the effects of Larmor precession and show that it gives rise to a qualitatively new type of multimode entangled state of light and atoms. The protocol is shown to be robust against the dominating sources of noise and can be implemented with an atomic ensemble at room temperature interacting with free space light. We also provide a scheme to perform the readout of the Larmor precessing spin state enabling the verification of successful teleportation as well as the creation of spin squeezing.

Optical manipulation of collective spin correlations in semiconductors with a squeezed vacuum of polarized photons

“…Schemes for transferring correlations from light to matter have recently been explored in atomic and molecular optics ͑AMO͒ both theoretically [11][12][13] and experimentally. [14][15][16] These schemes employ either coherent optical dipoles of atomic V systems or ground states coherence of ⌳ systems, leading to a second-order dependence of the spin fluctuations on the squeezed optical field. In semiconductors, one is faced with strong dephasing of optical dipoles as well as valence band spins due to Coulomb, electron-phonon, and spin-orbit interactions, rendering the above atomic optics schemes impractical.…”

Nonclassical States of Light and Mechanics

“…The main idea of quantum state teleportation in this context is to transfer an arbitrary quantum state |ψ in of a travelling wave light pulse onto the mechanical resonator, without any direct interaction between the two systems, but by making use of optomechanical entanglement. The scheme works in full analogy to the CV teleportation protocol for photons [80,81] and, due to its pulsed nature, closely resembles the scheme used in atomic ensembles [82,83]: A light pulse (A) is sent to the optomechanical cavity and is entangled with its mechanical mode (B) via the dynamics described above. Meanwhile a second pulse (V) is prepared in the state |ψ in , which is to be teleported.…”

Two-axis-twisting spin squeezing by multipass quantum erasure

“…The input light pulse is composed of a strong x-polarized component with carrier frequency ω 0 = 2πc/λ and a weak quantum component polarized along the y direction. The ypolarized component is relevant here and, in the narrow frequency band limit, can be described by spatially localized modes [26] …”

“…If the light pulse propagates along the z axis and is tuned far off the atomic resonance, the forward scattering process in a one-dimensional model is described by the Faraday-type Hamiltonian [2,26]…”