Error-immune quantum communication

TL;DR

This paper introduces a formalism that uses invariant quantities to enable error-immune quantum communication without the need for entanglement or state recovery, simplifying and potentially improving the reliability of quantum information transfer.

Contribution

It proposes a novel approach employing scaling laws to find invariant quantities under noise, eliminating the need for entanglement and error correction in quantum communication.

Findings

Invariant quantities identified for various noisy channels

Error-immune transmission achieved without entanglement

Cost-effective quantum communication scheme developed

Abstract

Environmental effects on the transmission of a state result, in general, in a change in the information carried by it. To mitigate this, many techniques such as quantum error--correcting codes, decoherence--free--subspaces [Rev Mod Phys, 88(4):041001, 2016] are employed. The basic idea underlying them is to protect/recover the state. These techniques require multi-party entanglement, whose generation is a difficult task. Further, retrieval of information would require complete tomography, which inevitably requires a large number of copies. Taking this into account, in this work, a formalism has been laid down which does not require recovery of a state. The formalism employs scaling laws to obtain quantities that remain invariant under a noisy evolution of a state. The information encoded in these invariant quantities can be transmitted in an error-immune manner. Since multiparty entanglement and error detection/correction will not be required, the proposed scheme would be cost-effective and may be reliably employed for error-free information transfer. Employing the formalism, we have obtained invariant quantities for various noisy channels of a qubit and a quNit.