Optimized Non-Gaussian Measurements for Communications and Metrology
- Physics and Astronomy Colloquium
October 2, 2026 3:30 PM -
October 2, 2026 4:30 PM
PAIS 1100
- Host:
- Greg Taylor
- Presenter:
- Prof. Elohim Becerra (UNM)
Quantum mechanics imposes fundamental limits on our ability to distinguish between different states of light, such as coherent states produced by lasers, due to intrinsic quantum noise. For Gaussian measurements, including homodyne and heterodyne detection, this noise gives rise to the quantum-noise limit (QNL), which constrains the performance of conventional coherent optical communications. Building on Helstrom's pioneering work, quantum measurement theory has shown that it is possible to surpass the QNL using optimized non-Gaussian measurements and potentially approach the ultimate limit allowed by quantum mechanics, the Helstrom bound.
These results have motivated novel detection schemes based on displacement operations and photon counting that outperform conventional Gaussian measurements. I will discuss recent theoretical and experimental advances in receivers that combine adaptive measurement strategies with single-photon detection to discriminate nonorthogonal coherent states below the QNL, even in the presence of noise and loss. These measurements have the potential to significantly reduce error rates and increase information transfer in low-power classical communications, with further applications in metrology.
