Bo Liu

The entanglement distribution networks with various topologies are mainly implemented by active wavelength multiplexing routing strategies. However, designing an entanglement routing scheme, which achieves the maximized network connections and the optimal overall network efficiency simultaneously, remains a huge challenge for quantum networks. In this article, we propose a differentiated service entanglement routing (DSER) scheme, which firstly finds out the lowest loss paths and supported wavelength channels with the tensor-based path searching algorithm, and then allocates the paired channels with the differentiated routing strategies. The evaluation results show that the proposed DSER scheme can be performed for constructing various large scale quantum networks.

Quantum digital signature is used to authenticate the identity of the signer with information theoretical security, while providing non-forgery and non-repudiation services. In traditional multireceiver quantum digital signature schemes without an arbitrater, the transferability of one-to-one signature is always required to achieve unforgeability, with complicated implementation and heavy key consumption. In this article, we propose an arbitrated quantum digital signature scheme, in which the signature can be verified by multiple receivers simultaneously, and meanwhile, the transferability of the signature is still kept. Our scheme can be simplified performed to various quantum secure networks, due to the proposed efficient signature calculation procedure with low secure key consumption and low computation complexity, by employing one-time universal hashing algorithm and one-time pad encryption scheme. The evaluation results show that our scheme uses at least two orders of magnitude less key than existing signature schemes with transferability when signing files of the same length with the same number of receivers and security parameter settings.

Quantum Key Distribution (QKD) allows unconditionally secure communication based on the laws of quantum mechanics rather then assumptions about computational hardness. Optimizing the operation parameters of a given QKD implementation is indispensable in order to achieve high secure key rates. So far, there exists no model that accurately describes entanglement-based QKD with continuous-wave pump lasers. For the first time, we analyze the underlying mechanisms for QKD with temporally uniform pair-creation probabilities and develop a simple but accurate model to calculate optimal trade-offs for maximal secure key rates. In particular, we find an optimization strategy of the source brightness for given losses and detection-time resolution. All experimental parameters utilized by the model can be inferred directly in standard QKD implementations, and no additional assessment of device performance is required. Comparison with experimental data shows the validity of our model. Our results yield a tool to determine optimal operation parameters for already existing QKD systems, to plan a full QKD implementation from scratch, and to determine fundamental key rate and distance limits of given connections.

To reduce the frame error rate of polar-based information reconciliation (IR) scheme with high reconciliation efficiency, we propose the Shannon-limit approached (SLA) IR scheme, in which the block checked decoder of polar code is proposed to determine the error sub-blocks in the forward reconciliation and the errors are corrected in the acknowledgment reconciliation. And the experimental results show that the SLA IR scheme reduces the $\varepsilon$-correctness to $10^{-8}$ and improves the efficiency to better than 1.091 with the IR block size of 128Mb. Otherwise, the SLA IR scheme reaches the efficiency of 1.055 with the quantum bit error rate (QBER) of 0.02, when the block length reaches to 1Gb, which is hundred times larger than the state-of-art implemented polar codes-based IR schemes and further reduce the finite length effect.