Simulating arbitrary Gaussian circuits with linear optics
Abstract
Linear canonical transformations of bosonic modes correspond to Gaussian unitaries, which comprise passive linearoptical transformations as effected by a multiport passive interferometer and active Bogoliubov transformations as effected by a nonlinear amplification medium. As a consequence of the BlochMessiah theorem, any Gaussian unitary can be decomposed into a passive interferometer followed by a layer of singlemode squeezers and another passive interferometer. Here, it is shown how to circumvent the need for active transformations. Namely, we provide a technique to simulate sampling from the joint input and output distributions of any Gaussian circuit with passive interferometry only, provided twomode squeezed vacuum states are available as a prior resource. At the heart of the procedure, we exploit the fact that a beam splitter under partial time reversal simulates a twomode squeezer, which gives access to an arbitrary Gaussian circuit without any nonlinear optical medium. This yields, in particular, a procedure for simulating with linear optics an extended boson sampling experiment, where photons jointly propagate through an arbitrary multimode Gaussian circuit followed by the detection of output photon patterns.
 Publication:

Physical Review A
 Pub Date:
 December 2018
 DOI:
 10.1103/PhysRevA.98.062314
 arXiv:
 arXiv:1803.11534
 Bibcode:
 2018PhRvA..98f2314C
 Keywords:

 Quantum Physics
 EPrint:
 12 pages, 4 figures