Quantum Signal Detection

Our research focuses on advancing quantum signal detection and spectroscopy by leveraging cutting-edge methodologies, from polarimetry to generalized quantum measurements (POVMs), and weak measurement schemes. A notable recent contribution is the exploration of terahertz (THz) photon detection and the demonstration of quantum-enhanced time domain spectroscopy [1,2].

Schematic of experimental realization of a deterministic scheme for joint quantum measurements

We have pioneered electro-optical sampling of single-cycle THz fields using single-photon detectors and squeezed vacuum states, achieving sensitivity limited by quantum noise properties. This approach marks a significant leap towards quantum-enhanced THz sensing and spectroscopy. Furthermore, our work extends to integrating weak-value amplification (WVA) techniques for measuring ultrasmall phase shifts, significantly improving detection under strong noise conditions.

A core achievement includes the demonstration of metasurface polarimeters capable of direct Stokes parameter measurements for arbitrary polarization states, offering high fidelity and resolution. These efforts contribute to a robust framework for quantum-enhanced measurements across different domains.

This work has been supported by grants from EPSRC and further showcases the practical applications of quantum metrology in emerging sensing technologies.

Selected Publications

  1. Adamou, D., Hirsch, L., Shields, T., Yoon, S., Dada, A.C., Weaver, J.M.R., Faccio, D., Peccianti, M., Caspani, L., Clerici, M. Quantum-Enhanced Time-Domain Spectroscopy. Science Advances, 11(4), eadt2187 (2025).
  2. Shields, T., Dada, A.C., Hirsch, L., et al. Electro-Optical Sampling of Single-Cycle THz Fields with Single-Photon Detectors. Sensors, 22, 9432 (2022).
  3. Huang, J., Lundeen, J., Dada, A.C., et al. Autocorrelative Weak-Value Amplification and Simulating the Protocol under Strong Gaussian Noise. Physical Review A, 106, 053704 (2022).
  4. Huang, J., Lundeen, J., Dada, A.C., et al. Weak-Value-Amplification Enhancement of the Magneto-Optical Kerr Effect in Nanoscale Layered Structures. Physical Review A, 108, 033724 (2023).
  5. Shah, Y.D., Dada, A.C., et al. An All-Dielectric Metasurface Polarimeter. ACS Photonics, 9, 3245–3252 (2022).
  6. Waldherr, G., Dada, A.C., et al. Distinguishing Between Nonorthogonal Quantum States of a Single Nuclear Spin. Physical Review Letters, 109, 180501 (2012).
  7.  Dada, A.C., et al. Optimal simultaneous measurements of incompatible observables of a single photon. Optica, 6(3), 257-263 (2019).