Gershoni, David
Date: Thursday, January 9, 2020
Time: 14:00
Place: ETH Zurich, Hönggerberg, HPF G 6
Host: Ataç İmamoğlu
On Demand Sources of Cluster States of Entangled Photons
David Gershoni*
Technion–Israel Institute of Technology, Israel
Photonic cluster states are a resource for quantum computation based solely on single-photon measurements [1]. We use semiconductor quantum dots to deterministically generate long strings of polarization-entangled photons in a cluster state by periodic timed excitation of a precessing matter qubit [1-2]. In each period, an entangled photon is added to the cluster state formed by the matter qubit and the previously emitted photons. In our prototype device, the qubit is the confined dark exciton [3-4], and it produces strings of hundreds of photons at rates which exceed 1 GHz. The entanglement in the string persists over five sequential photons [5], but it can be increased substantially. We developed a novel method for characterizing this multi-photon quantum state using three qubits correlation measurements only [7]. Using these novel entangled multi-photon states for super-sensitive optical phase measurements will be demonstrated and discussed.
*Work done in collaboration with Dan Cogan, Giora Penaikov and Zu-En Su
References:
[1] H. J. Briegel, „Versatile cluster entangled light" , Science 354, 416 (2016)
[2] N. H. Lindner and T. Rudolph, „Proposal for Pulsed On-Demand Sources of Photonic Cluster State Strings“ Phys. Rev. Lett. 103, 113602 (2009)
[3] E. Poem, et al, „Accessing the dark exciton with light "Nature Physics 6, 993, (2010)
[4] I. Schwartz, et al, „Deterministic writing and control of the dark exciton spin using short single optical pulses". Phys. Rev. X 5, 011009 (2015)
[5] D. Cogan, et al „Depolarization of Electronic Spin Qubits Confined in Semiconductor Quantum Dots“. Phys. Rev. X 8, 041050 (2018)
[6] I. Schwartz, et al, „Deterministic generation of a cluster state of entangled photons.” Science, 354, 434 (2016)
[7] D. Cogan et al, "Complete state tomography of a quantum dot confined spin qubit" arXiv:1910.05024 (2019)