Quantum error code correction in PRL

Tuesday 29 Oct 13
We published our experimental demonstration of a quantum error code correction protocol in Physical Review Letters.

Quantum communication is the exchange of information over long distances between parties by means of transmission of quantum states through a communication channel, and it has a number of applications such as Quantum Key Distribution (QKD) and Quantum Computing. Unfortunately, realistic communication channels are inevitably noisy, and this leads to errors that are detrimental to the fidelity of the transmitted quantum states. Quantum error correction provides the tools to protect the quantum information from the noise, allowing the achievement of fault-tolerant quantum computation and secure QKD.

Quantum error code correction

In this paper, we demonstrate experimentally a communication protocol which can protect the transmitted quantum states against correlated polarization noise.
The correction is accomplished by means of simple linear optical operations:
the quantum signal is split into orthogonal polarization modes using a polarizing beam splitter (PBS). After the PBS, one of the two polarization modes is phase shifted to be out of phase with respect to the other mode (Encoding). The two modes enter the noisy channel, where non-Markovian additive polarization noise introduces correlated errors in both polarization modes. The two modes are then properly mixed again (Decoding) on a second PBS and as a result, all the noise is collected in one mode while all the clean information is collected in the other, orthogonal mode.
We demonstrate that our protocol outperforms classical correction strategies for coherent signal inputs and is also capable of preserving entanglement in highly noisy channels.

Read the paper here.