High-fidelity teleportation between light and atoms

We show how high-fidelity quantum teleportation of light to atoms can be achieved in the same setup as was used in the recent experiment [J. Sherson et al., Nature443, 557, 2006], where such an interspecies quantum state transfer was demonstrated for the first time. Our improved protocol takes advantage of the rich multimode entangled structure of the state of atoms and scattered light and requires simple postprocessing of homodyne detection signals and squeezed light in order to achieve fidelities up to 90% (85%) for teleportation of coherent (qubit) states under realistic experimental conditions. The remaining limitation is due to atomic decoherence and light losses.

Figure 1

Teleportation fidelity $F$ and added noise in units of shot noise for coherent states vs coupling $\kappa$ for different numbers of modes $N$ included in the protocol, optimized for the parameters $c_n$ determining the pulse shape of the input mode. The dashed line is the fidelity achievable if only the zeroth order mode, $N=0$, is included (c.f. [1, 2]). The thin line corresponds to $N=1$. The results for $N=2$ and $N=3$ (thick line) are practically identical and saturate the bound of $F=80\%$. Inset: Optimal envelope for the input field for the case $N=3,\kappa =2$, normalized over pulse duration $[0,T]$.

Figure 2

(a) Teleportation fidelity $F$ and added noise in units of shot noise for coherent states vs coupling $\kappa$ for protocols involving four modes $(N=3)$ using squeezing of light down to $-3,-6$, and $-10\mathrm{dB}$. The curve for $0\mathrm{dB}$ is identical to the thick line of Fig. 1. Inset: optimal envelope for the input field for $-10\mathrm{dB}$ of squeezing and $\kappa =2$, normalized over pulse duration $[0,T]$. (b) Teleportation fidelity $F$ and added noise in units of shot noise for coherent states vs coupling $\kappa$ including 10% atomic decay and 10% light losses. The optimal pulse shape is practically identical to the one shown in the inset of (a).

Figure 3

(a) Teleportation fidelity $F$ for qubit states vs coupling $\kappa$ for protocols involving four modes $(N=3)$ using squeezing of light down to $-3,-6$, and $-10\mathrm{dB}$, averaged over the Bloch sphere. Inset: Optimal envelope for the input field for $-10\mathrm{dB}$ of squeezing and $\kappa =2$, normalized over pulse duration $[0,T]$. (b) Teleportation fidelity $F$ for qubit states vs coupling $\kappa$ including 10% atomic decay and 10% light losses, averaged over the Bloch sphere. The optimal pulse shape is practically identical to the one in shown in the inset of (a).