Quantum optics seminar
Temporal Entanglement and Witnesses of Non-Classicality
Mr. Giuseppe Di Pietra
University of Oxford
Abstract
Link: https://us02web.zoom.us/j/83777039121?pwd=6Yq4RSa9PwS1riZpI71E2GQN2Yu8SG.1
Abstract:
Temporal entanglement — correlations generated during the time evolution of a single system — represents a largely unexplored resource in quantum theory. While its spatial counterpart, generated between two distinct subsystems, underpins quantum information processing and computation, the asymmetry between space and time in quantum theory has hindered an equivalent role for entanglement in time.
In this work, we present the first concrete application of temporal entanglement as a quantum resource by linking its theory to recently proposed information-theoretic, table-top tests to witness quantum effects in a physical system. We introduce a protocol to witness the non-classicality of an unknown system by probing it with a single qubit. Assuming a general conservation law, we show that the violation of temporal Bell inequalities on the qubit probe implies the non-classicality of the system under investigation. We further perform proof-of-principle experimental emulations of the proposed witness of non-classicality, using a three-qubit Nuclear Magnetic Resonance quantum computer.
These experiments constitute the first realisation of temporal entanglement on a quantum platform, demonstrating its accessibility in practice. The underlying witness protocol is robust, relying on minimal and physically motivated assumptions. Our results identify temporal entanglement as a genuine operational resource, opening new avenues for its exploitation in quantum computing and, remarkably, in the study of quantum phenomena in a broad range of contexts, from biology to gravity.
Abstract:
Temporal entanglement — correlations generated during the time evolution of a single system — represents a largely unexplored resource in quantum theory. While its spatial counterpart, generated between two distinct subsystems, underpins quantum information processing and computation, the asymmetry between space and time in quantum theory has hindered an equivalent role for entanglement in time.
In this work, we present the first concrete application of temporal entanglement as a quantum resource by linking its theory to recently proposed information-theoretic, table-top tests to witness quantum effects in a physical system. We introduce a protocol to witness the non-classicality of an unknown system by probing it with a single qubit. Assuming a general conservation law, we show that the violation of temporal Bell inequalities on the qubit probe implies the non-classicality of the system under investigation. We further perform proof-of-principle experimental emulations of the proposed witness of non-classicality, using a three-qubit Nuclear Magnetic Resonance quantum computer.
These experiments constitute the first realisation of temporal entanglement on a quantum platform, demonstrating its accessibility in practice. The underlying witness protocol is robust, relying on minimal and physically motivated assumptions. Our results identify temporal entanglement as a genuine operational resource, opening new avenues for its exploitation in quantum computing and, remarkably, in the study of quantum phenomena in a broad range of contexts, from biology to gravity.