http://hdl.handle.net/10453/148704 2026-08-04T21:47:37Z http://hdl.handle.net/10453/195842 Title: Interplay of quantum resources in nonlocality tests Authors: Dong, HH; Zhu, Y; Cheng, SY; Zhang, X; Li, CL; Li, YZ; Li, H; You, L; Ma, X; Zhang, Q; Pan, JW Abstract: Nonlocality, evidenced by the violation of Bell inequalities, not only signifies entanglement but also highlights measurement incompatibility in quantum systems. Utilizing the tilted Clauser-Horne-Shimony-Holt (CHSH) Bell inequality, our high-efficiency optical setup achieves a loophole-free violation of 2.0132. This result provides a device-independent lower bound on entanglement, quantified as the entanglement of formation at 0.0159. Moreover, by tuning the parameters of the tilted CHSH inequality, we enhance the estimation of measurement incompatibility, which is quantified by an effective overlap of 4.3883×10-5. To explore the intricate interplay among nonlocality, entanglement, and measurement incompatibility, we generate mixed states, allowing for flexible modulation of entanglement via fast switching among the four Bell states using Pockels cells, achieving a fidelity above 99.10%. Intriguingly, our results reveal a counterintuitive relationship where increasing incompatibility initially boosts nonlocality but eventually leads to its reduction. Typically, maximal nonlocality does not coincide with maximal incompatibility. This experimental study sheds light on the optimal management of quantum resources for Bell-inequality-based quantum information processing. 2025-04-01T00:00:00Z http://hdl.handle.net/10453/195799 Title: Virtual Channel Purification Authors: Liu, Z; Zhang, X; Fei, YY; Cai, Z Abstract: Quantum error mitigation is a key approach for extracting target state properties on state-of-the-art noisy machines and early fault-tolerant devices. Using the ideas from flag fault tolerance and virtual state purification, we develop the virtual-channel-purification (VCP) protocol, which consumes similar qubit and gate resources as virtual state purification but offers stronger error suppression with increased system size and more noisy operation copies. The application of VCP does not require specific knowledge about the target quantum state, the target problem and the gate noise model in the target circuit, and can still offer rigorous performance guarantees for practical noise regimes as long as the noise is incoherent. Further connections are made between VCP and quantum error correction to produce the virtual error-correction (VEC) protocol, one of the first protocols that combine quantum error correction (QEC) and quantum error mitigation beyond directly applying error-mitigation protocols on top of logical qubits. Assuming perfect syndrome extraction, VEC can virtually remove all correctable noise in the channel while paying only the same sampling cost as low-order purification. It can achieve QEC-level protection on an unencoded register when transmitting it through a noisy channel, removing the associated encoding qubit overhead. Another variant of VEC can mimic the error-suppression power of the surface code by inputting only a bit-flip and a phase-flip code. Our protocol can also be adapted to key tasks in quantum networks like channel capacity activation and entanglement distribution. 2025-04-01T00:00:00Z http://hdl.handle.net/10453/195710 Title: From data to practice change: Co-designing a subject dashboard that enables inclusive, evidence-informed teaching Authors: Egea, K; Atif, A; Paul, G; Matiuk, S; McKenzie, J 2026-07-01T00:00:00Z http://hdl.handle.net/10453/195688 Title: Dynamic Continuous Variable Quantum Key Distribution for Securing a Future Global Quantum Network Authors: Sayat, MT; Kish, SP; Lam, PK; Rattenbury, NJ; Cater, JE Abstract: Abstract Continuous variable quantum key distribution (CVQKD) is a developing method to secure information exchange in future quantum networks. With the recent developments in quantum technology and greater access to space, a global quantum network secured by CVQKD can be within reach. In this work, the structures of existing QKD networks are analyzed, and how they can be fit into a general overarching three‐layer QKD network architecture for the endeavor of a global QKD network. Such a network can comprise different links in fiber and free‐space. The finite size limit secret key rates (SKRs) with multidimensional reconciliation are calculated for the different links for which CVQKD can be used in such a network. The results show that CVQKD generally achieves longer distances and larger SKRs in inter‐satellite, satellite‐to‐ground, fiber, and underwater links in descending order. The different links and nodes are classified and secret key distribution is studied as a graph problem. The link capacity, a routing metric for secret key distribution, which considers a dynamic SKR based on dynamic links is presented. Its use in simulated CVQKD networks is presented for the aim of spatiotemporal secret key distribution through a dynamic CVQKD network. 2025-10-01T00:00:00Z