Experimental Demonstration of Quantum Source Coding

We report an experimental demonstration of Schumacher’s quantum noiseless coding theorem. Our experiment employs a sequence of single photons, each of which represents three qubits in terms of eight spatial and polarization modes. We initially prepare each photon in one of a set of eight nonorthogonal code word states corresponding to the value of a block of three binary letters. We use quantum coding to compress this quantum data into a two-qubit quantum channel and then uncompress the two-qubit channel to restore the original data with a fidelity approaching the theoretical limit.

Figure 1

Comparison of the fidelities of various protocols as a function of the parameter ${\alpha }^2$.

Figure 2

Linear optics implementation of three-qubit block coding and decoding.

Figure 3

Experimental setup.

Figure 4

Histogram of photon counts for each block state $\mathbf{L}$ for ${\alpha }^2=0.9046$. The port numbers refer to APD1 to APD6.