Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group
Journal Home About Issues in Progress Current Issue All Issues Feature Issues

8×8 reconfigurable quantum photonic processor based on silicon nitride waveguides

Caterina Taballione, Tom A. W. Wolterink, Jasleen Lugani, Andreas Eckstein, Bryn A. Bell, Robert Grootjans, Ilka Visscher, Dimitri Geskus, Chris G. H. Roeloffzen, Jelmer J. Renema, Ian A. Walmsley, Pepijn W. H. Pinkse, and Klaus-J. Boller

Open Access Open Access

Abstract

The development of large-scale optical quantum information processing circuits ground on the stability and reconfigurability enabled by integrated photonics. We demonstrate a reconfigurable 8×8 integrated linear optical network based on silicon nitride waveguides for quantum information processing. Our processor implements a novel optical architecture enabling any arbitrary linear transformation and constitutes the largest programmable circuit reported so far on this platform. We validate a variety of photonic quantum information processing primitives, in the form of Hong-Ou-Mandel interference, bosonic coalescence/anti-coalescence and high-dimensional single-photon quantum gates. We achieve fidelities that clearly demonstrate the promising future for large-scale photonic quantum information processing using low-loss silicon nitride.

Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Full Article  |  PDF Article
More Like This
Silicon nitride programmable photonic processor with folded heaters

Daniel Pérez-López, Ana Gutiérrez, and José Capmany
Opt. Express 29(6) 9043-9059 (2021)

High-fidelity and large-scale reconfigurable photonic processor for NISQ applications

A. Cavaillès, P. Boucher, L. Daudet, I. Carron, S. Gigan, and K. Müller
Opt. Express 30(17) 30058-30065 (2022)

Photonic-reconfigurable entanglement distribution network based on silicon quantum photonics

Dongning Liu, Jingyuan Liu, Xiaosong Ren, Xue Feng, Fang Liu, Kaiyu Cui, Yidong Huang, and Wei Zhang
Photon. Res. 11(7) 1314-1325 (2023)

View More...

Cited By

Optica participates in Crossref's Cited-By Linking service. Citing articles from Optica Publishing Group journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (10)
Fig. 1.
Fig. 1. Schematic geometrical layout of the programmable silicon nitride linear optical waveguide network where tight guiding in high-contrast SiN waveguides is exploited to form a dense waveguide mesh, with currently 21 Mach-Zehnder interferometers per square centimeter. Bullets indicate the injection of single photons via the front or side facets of the chip. The circuit contains delay lines to equalize photon arrival and departure times at the front and back ports of the internal interferometers. The location of electric heaters with feed wires and bond pads is shown at the top surface in gold. Choosing bullets with different colors indicates that the wide transparency range of the waveguides allows using the processor with quantum light sources over a wide spectral range, from the visible to the mid-infrared.

Download Full Size | PDF

Fig. 2.
Fig. 2. Schematic of the experimental setup. (a) The photonic processor is composed of 64 unit cells, each comprising a phase shifter (red vertical line) and a tunable beam splitter (blue horizontal line) implemented as a Mach-Zehnder interferometer. The rhomboidal shape of the processor’s schematic has been chosen for better overview. In the real processor the elements are arranged on a square mesh. (b) Photon pairs are generated via type-II parametric down-conversion in PPKTP waveguides pumped with a mode-locked laser at 775 nm and injected into the photonic processor.

Download Full Size | PDF

Fig. 3.
Fig. 3. Transmission of the first accessible tunable beam splitter. The diamonds are the experimental data and the blue dashed line is the sinusoidal fit. The visibility of the sinusoid gives the range of splitting ratio achievable and the period of the sinusoid is related to the phase shift induced by the tunable element.

Download Full Size | PDF

Fig. 4.
Fig. 4. (a) Two-photon interference at various locations of the processor (colored circles), also indicating the used pairs of input waveguides (bullets of the same color). (b) Coincidence probability versus delay. The two-photon interference measured at the tunable beam splitters on the processor (red data points) is well in accord with the off-chip reference measurement (blue data points). All the investigated beam splitters show a similar visibility. The solid curves indicates Gaussian fits to the data. The error bars are given by the square root of the number of coincidences.

Download Full Size | PDF

Fig. 5.
Fig. 5. (a) Implementation of a lossy beam splitter on a 2×2 Blass matrix. The black elements are set accordingly to the desired T. (b) Coincidence versus delay for two different lossy transformations T. Measured two-photon bosonic coalescence (red curve)/anti-coalescence (blue curve) with a visibility of 81% and 70% respectively.

Download Full Size | PDF

Fig. 6.
Fig. 6. (a) Realization of an 8-dimensional X-gate and (b) its measured truth table. (c) Truth tables of integer powers of the X-gate reported above. The average fidelity is ${{{\cal F}}_{8 \times 8}} = 94.6\%$. (d) Evolution of a coherent superposition input state $|\pm \rangle = (1/\sqrt 2 )({|{{1\rangle_5} \pm } |{1\rangle_6}} )$ through a 6-dimensional X-gate, giving a fidelity of $\; 91.9\%$.

Download Full Size | PDF

Fig. 7.
Fig. 7. Schematic of a universal linear optical network. The unit cell (dashed frame) comprises a tunable beam splitter in the form of a tunable Mach-Zehnder interferometer with two directional couplers and a phase shifter in one arm of length ${L_t}$ (red), followed by an external phase shifter (${L_t}$, red). The path length through the unit cell is determined by the length of the straight-waveguide tunable elements and the length of curved waveguides (radius of curvature R).

Download Full Size | PDF

Fig. 8.
Fig. 8. Functional complexity calculated for three different platforms: silicon nitride (red curve), SOI (blue) and doped silica (green). The highest functional complexity achieved in previous work is indicated as data points, i.e., [1,46] realized in SOI, [17] in doped silica and this work realized with silicon nitride.

Download Full Size | PDF

Fig. 9.
Fig. 9. Schematic of how to implement a d-dimensional X-gate on a d-dimensional linear optical network.

Download Full Size | PDF

Fig. 10.
Fig. 10. Overview of planar waveguide propagation loss versus bending radius as in [63] with more recent works [1,61,62,64]. The loss value for large radius tends to ${\alpha _s}$.

Download Full Size | PDF

Tables (1)

Tables Icon

Table 1. Parameters used for the functional complexity calculation.

View Table
Select as filters
Select Topics Cancel
Top
       
© Copyright 2024 | Optica Publishing Group. All rights reserved, including rights for text and data mining and training of artificial technologies or similar technologies.
Privacy | Terms of Use