Lecturer: Shahaf S. Asban
Abstract:
Quantum systems are notoriously sensitive to changes in their environment. This renders them extraordinary probes for sensing applications. Quantum probes undergo transitions when coupled to an external environment, encoding trajectory dependent quantum information in their statistics. Decoding this information requires a new set of inference methodologies, such as the one discussed below.

Entangled photon pairs have inspired a myriad of quantum-enhanced metrology platforms, which outperform their classical counterparts. However, the role of photon exchange-phase and degree of distinguishability have not yet been utilized in quantum-enhanced applications. We show that when a two-photon wave-function is coupled to matter, it is encoded with "which pathway?" information even at a low degree of entanglement. An interferometric exchange-phase-cycling protocol is developed, revealing phase-sensitive information for each interaction history separately. Moreover, we find that quantum-light multimode interferometry facilitates a new set of time variables that enable time-resolved signals, unbound by uncertainty to the inverse bandwidth of the wave-packet. We illustrate our findings on an exciton model-system and discuss future applications.