Abstract
A major challenge of today's quantum communication systems lies in the transmission of quantum information with high rates over long distances in the presence of unavoidable losses. Thereby the achievable quantum communication rate is fundamentally limited by the amount of energy that can be transmitted per use of the channel. It is hence vital to develop quantum communication protocols that encode quantum information as energy efficiently as possible. To this aim we investigate continuous-variable quantum teleportation as a method of distributing quantum information. We explore the possibility to encode information on multiple optical modes and derive upper and lower bounds on the achievable quantum channel capacities. This analysis enables us to benchmark single-mode versus multi-mode entanglement resources. Our research reveals that multiplexing does not only feature an enhanced energy efficiency, leading to an exponential increase in the achievable quantum communication rates in comparison to single-mode coding, but also yields an improved loss resilience. However, as reliable quantum information transfer is only achieved for entanglement values above a certain threshold a careful optimization of the number of coding modes is needed to obtain the optimal quantum channel capacity.
Highlights
Information theoretical characterization of CV quantum teleportationThere exist different figures of merit to quantify the accuracy of CV teleportation. Among others there is the fidelity of quantum teleportation, detailing how closely the state arriving at Bob’s side resembles the original state from Alice
We propose a practical setup to implement the proposed multiplexing by encoding the information on ultrafast optical pulse modes5
There exist a wide variety of sources capable of creating the required entangled states suitable for CV quantum teleportation, ranging from optical parametric oscillators [8,9,10] over four-wave mixing in optical fibers featuring a χ (3) nonlinearity [11, 12] to parametric downconversion (PDC) in nonlinear χ (2) crystals [13,14,15,16,17]
Summary
There exist different figures of merit to quantify the accuracy of CV teleportation. Among others there is the fidelity of quantum teleportation, detailing how closely the state arriving at Bob’s side resembles the original state from Alice. In the scope of this paper, we characterize the teleportation channel in terms of its quantum capacity [20, 21], this means the highest rate at which quantum information can be reliably transmitted through the channel when Alice and Bob make use of error correction to convey quantum information through the noisy channel. The thermal-like noise added by non-ideal teleportation can be counteracted by employing quantum error correction codes These can increase the quality of the communication (e.g. in terms of the fidelity) at the cost of reducing the communication rate.
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