Austin P. Lund

A significant hurdle for quantum information and processing using bosonic systems is stochastic phase errors which occur as the photons propagate through a channel. These errors will reduce the purity of states passing through the channel and therefore reduce the channels capacity. We present a scheme of passive linear optical unitary averaging for protecting unknown Gaussian states transmitted through an optical channel.

We consider the impact of the unitary-averaging framework on single- and two-mode linear optical gates. We demonstrate that this allows a trade-off between the probability of success and gate fidelity, with perfect fidelity gates being achievable for a finite decrease in the probability of success, at least in principle. Furthermore, we show that the encoding and decoding errors in the averaging scheme can also be suppressed up to the first order.

Popular Summary Noiseless linear amplifiers (NLAs) have the extraordinary ability to amplify quantum states without adding any additional noise. Therefore, NLAs have the potential to revolutionize quantum information protocols, including the areas of quantum communication, quantum computing, and quantum sensing. Unfortunately, NLAs can only work successfully based on chance, and making an NLA with good success efficiency is an important challenge.