Dr. Hagai Eisenberg - The Path to an All-Optical Quantum Computer - How Far Can We Go?
Date: Monday, March 4 2020, at 14:00pm (Israel time)
Abstract
Single photons are one of the most promising realizations of quantum bits (qubits), as they are easily manipulated, preserve their coherence for long times, and information can be stored in their many different degrees of freedom. The generation of entanglement between more than two particles is a major challenge for all physical realizations, including photons. It is required for the realization of many quantum information protocols, especially for quantum computing. Up to date, up to 12 photons have been entangled in a single state through their polarization degree of freedom. The main difficulties in increasing this number are the elaborated setups required and the low rates of state production.
I will present a novel and simple scheme that can in principle generate entanglement between any number of photons in a linear cluster state from a single fixed setup. This scheme combines photons from one source in a single path, but at different times, using an optical delay. It can be extended to create higher-dimensional cluster states, and even arbitrary graph states. Such states constitute the one-way quantum computer scheme. Results from such a setup using a quantum dot single photon source will be presented. States of up to four entangled photons were measured, with good visibilities of their quantum interference. The further prospects of this approach will be discussed.
“A resource efficient source of multi-photon polarization entanglement”, E. Megidish, T. Shacham, A. Halevy, L. Dovrat and H.S. Eisenberg, Phys. Rev. Lett. 109, 080504 (2012).
“Entanglement swapping between photons that have never coexisted”, E. Megidish, A. Halevy, T. Shacham, T. Dvir, L. Dovrat, and H. S. Eisenberg, Phys. Rev. Lett. 110, 210403 (2013).
“Simple source for large linear cluster photonic states”, Y. Pilnyak, N. Aharon, D. Istrati, E. Megidish, A. Retzker, H. S. Eisenberg, Phys. Rev. A 95, 022304 (2017)
“Sequential generation of linear cluster states from a single photon emitter”, D. Istrati et al., arXiv:1912.04375 [quant-ph]
