• CQuIC Seminars

November 5, 2025 4:00 PM
PAIS 2540

Presenter:

Morteza Darvishi

Discriminating between nonorthogonal quantum states lies at the heart of quantum information processing and quantum communication. However, due to the fundamental overlap between such states, perfect discrimination is impossible, and different quantum measurements must be employed depending on the desired trade-off between accuracy and conclusiveness.

In this talk, I will explore three key paradigms of quantum state discrimination — Minimum Error Discrimination (MED), Unambiguous Discrimination (UD), and their generalized form, the Optimal Inconclusive Measurement (OIM). Starting with a kind of definition of quantum state discrimination, I will introduce coherent states and then I will present two foundational measurement paradigms, MED and UD, highlighting their differences and limitations. Based on these concepts, I will introduce the OIM framework, discussing its physical realization through displacement operations, adaptive feedback, and single-photon detection.

Next, I will examine an experimental realization of OIM for unambiguous discrimination, demonstrating how OIM can give us a lower error probability in discriminating between binary coherent states.

Finally, I will address the problem of finding optimal measurements under noise, presenting the concept of noisy POVMs and their role in achieving optimal discrimination in realistic conditions. Through this study, we aim to provide a unified understanding of quantum measurements in the presence of noise, bridging theory and experiment to realize optimal state discrimination measurements in practical quantum optical systems.