Ultrafast quantum communications over long distances using quantum encoding

Linshu Li, Victor V. Albert, Marios Michael +3 more

Liang Jiang, Sreraman Muralidharan, Jungsang Kim +2 more

We investigate quantum repeaters using small encoding blocks to correct both operational and photon loss errors, which can send quantum information over long distances at a rate only limited by local gate speed.

Sreraman Muralidharan, Liang Jiang

Nicoló Lo Piparo

Sreraman Muralidharan, Jungsang Kim, Norbert Lütkenhaus +2 more

Quantum repeaters (QRs) provide a way of enabling long distance quantum communication by establishing entangled qubits between remote locations. In this Letter, we investigate a new approach to QRs in which quantum information can be faithfully transmitted via a noisy channel without the use of long distance teleportation, thus eliminating the need to establish remote entangled links. Our approach makes use of small encoding blocks to fault-tolerantly correct both operational and photon loss errors. We describe a way to optimize the resource requirement for these QRs with the aim of the generation of a secure key. Numerical calculations indicate that the number of quantum memory bits at each repeater station required for the generation of one secure key has favorable polylogarithmic scaling with the distance across which the communication is desired.

Connor Kupchak, Philip J. Bustard, Khabat Heshami +4 more

The encoding of quantum information in photonic time-bin qubits is apt for long-distance quantum communication schemes. In practice, due to technical constraints such as detector response time, or the speed with which copolarized time-bins can be switched, other encodings, e.g., polarization, are often preferred for operations like state detection. Here, we present the conversion of qubits between polarization and time-bin encodings by using a method that is based on an ultrafast optical Kerr shutter and attain efficiencies of 97% and an average fidelity of $0.827\ifmmode\pm\else\textpm\fi{}0.003$ with shutter speeds near 1 ps. Our demonstration delineates an essential requirement for the development of hybrid and high-rate optical quantum networks.