Southwest Quantum Information and Technology

Towards full characterization of photonic gates with weak local oscillators

Presenting Author: Arik Avagyan, National Institute of Standards and Technology, Boulder
Contributing Author(s): Emanuel, Knill Scott, Glancy

It is well established theoretically and experimentally that using a strong local oscillator in a coherent state in a homodyne configuration allows one to reconstruct the state of the input mode matching the mode of the local oscillator (LO) [1]. Less attention has been paid to the problem of performing homodyne quantum state tomography when the LO is in an arbitrary weak single-mode state. However, several recently performed and proposed experiments studying the propagation and transformation of photons in engineered cold Rydberg clouds could benefit from such a tomography scheme, because in these experiments the LO is sent through the atomic cloud, which puts a severe upper limit on the LO amplitude [2]. We first seek to determine which LO states with their phase variants can fully characterize the matching input mode state and what can be learned about unmatched input modes. We then plan to investigate process tomography on photonic gates with a weak LO. These results will help characterize photonic logic gates achieved through light-atom interactions, where the application of a strong LO is not feasible. 1.A. I. Lvovsky and M. G. Raymer, Continuous-variable optical quantum-state tomography. Rev. Mod. Phys. 81, 299 (16 March 2009) 2. Thompson, Jeff D. et al, Symmetry-protected collisions between strongly interacting photons. /Nature/ 542, 206–209 (09 February 2017)

(Session 5 : Thursday from 5:00pm - 7:00 pm)