Past Seminars

2023-05-18 10:00:00 | America/New_York

Sajede Harraz University of Science and Technology of China

Overcoming Noise: Achieving High-Fidelity Quantum Teleportation Through Weak Measurements

Quantum teleportation, as a key protocol for quantum communication and quantum computing, demonstrates the stark difference between quantum and classical information transmission. An ideal teleportation protocol requires a pure maximally entangled state as the teleportation channel, while in real implementations the shared entanglement is severely degraded due to decoherence. In this talk, I will demonstrate how the utilization of weak measurement and environment-assisted measurement can enhance the performance of teleportation in the presence of noise to a considerable extent.

Speaker's Bio

Sajede Harraz is a postdoctoral fellow at the University of Science and Technology of China (USTC). She received her Ph.D. in quantum system control from USTC in 2018. Prior to that, she received her M.Sc. degree in network security from Sharif University of Technology. Her current research interests include quantum state estimation, quantum state protection, and quantum communications through noisy channels.

2023-05-04 13:00:00 | America/New_York

Luís Bugalho LIP6, Sorbonne Université, CNRS, Paris, France & Physics of Information and Quantum Technologies Group, CeFEMA, Lisbon, Portugal

Distributing Multipartite Entanglement over Noisy Quantum Networks

A quantum internet aims at harnessing networked quantum technologies, namely by distributing bipartite entanglement between distant nodes. However, multipartite entanglement between the nodes may empower the quantum internet for additional or better applications for communications, sensing, and computation. In this work, we present an algorithm for generating multipartite entanglement between different nodes of a quantum network with noisy quantum repeaters and imperfect quantum memories, where the links are entangled pairs. Our algorithm is optimal for GHZ states with 3 qubits, maximising simultaneously the final state fidelity and the rate of entanglement distribution. Furthermore, we determine the conditions yielding this simultaneous optimality for GHZ states with a higher number of qubits, and for other types of multipartite entanglement. Our algorithm is general also in the sense that it can optimise simultaneously arbitrary parameters. In this talk I'll also go through some extensions of this work, in particular for the case where the parameters are described by a continuous function, correspondent to a trade-off model between fidelity and rate.

Speaker's Bio

Luis Bugalho is a Portuguese physicist currently doing research as a PhD student between CeFEMA in Lisbon and LIP6 in Paris. In the past years he has studied some aspects of distributing entanglement over quantum networks. His current area of research is related with quantum sensor networks, which harness the power of distributed quantum sensing.