Noiseless Conditional Teleportation of a Single Photon

We experimentally demonstrate the noiseless teleportation of a single photon by conditioning on quadrature Bell measurement results near the origin in phase space and thereby circumventing the photon loss that otherwise occurs even in optimal gain-tuned continuous-variable quantum teleportation. In general, thanks to this loss suppression, the noiseless conditional teleportation can preserve the negativity of the Wigner function for an arbitrary pure input state and an arbitrary pure entangled resource state. In our experiment, the positive value of the Wigner function at the origin for the unconditional output state, $W(0,0)=0.015\pm 0.001$, becomes clearly negative after conditioning, $W(0,0)=-0.025\pm 0.005$, illustrating the advantage of noiseless conditional teleportation.

Figure 1

Overview of gain-tuned continuous-variable quantum teleportation conditioned by the sender.

Figure 2

Probability $P(L)$ of CV-BSM falling inside conditioning radius $L\ge 0$ ($\hslash =1$). (i) Experimental results. (ii) Theoretical prediction based on the experimental input photon number distribution together with the single-mode squeezing parameter $r=1.62$ for the EPR state and optical loss $l=0.20$. (iii) Theoretical curve for CV-BSM on two-mode vacuum states. (iv),(v) $L=0.5$ and $L=2.0$ used in Fig. 3. Inset: experimentally obtained CV-BSM distribution.

Figure 3

Experimental quantum states reconstructed by the maximum likelihood method [41]. (a) Input single-photon state. (b) Output state without conditioning. (c),(d) Output states conditioned by $L=2.0$ and $L=0.5$, respectively. Top: photon number distribution. The sum of odd photon number components exceeding the horizontal line at 0.5 means a Wigner function negative at the origin. Bottom: side view of the Wigner function.