20-Mode Universal Quantum Photonic Processor
Caterina Taballione, Malaquias Correa Anguita, Michiel de Goede, Pim Venderbosch, Ben Kassenberg, Henk Snijders, Narasimhan Kannan, Ward Vleeshouwers, Devin H. Smith, Jörn P. Epping, Reinier van der Meer, Pepijn W. H. Pinkse, Hans van den Vlekkert, Jelmer J. Renema
Abstract
Integrated photonics is an essential technology for optical quantum computing. Universal, phase-stable, reconfigurable multimode interferometers (quantum photonic processors) enable manipulation of photonic quantum states and are one of the main components of photonic quantum computers in various architectures. In this paper, we report the realization of the largest quantum photonic processor to date. The processor enables arbitrary unitary transformations on its 20 input modes with an amplitude fidelity of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>F</mml:mi><mml:mrow class="MJX-TeXAtom-ORD"><mml:mtext>Haar</mml:mtext></mml:mrow></mml:msub><mml:mo>=</mml:mo><mml:mn>97.4</mml:mn><mml:mi mathvariant="normal">&#x0025;</mml:mi></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>F</mml:mi><mml:mrow class="MJX-TeXAtom-ORD"><mml:mtext>Perm</mml:mtext></mml:mrow></mml:msub><mml:mo>=</mml:mo><mml:mn>99.5</mml:mn><mml:mi mathvariant="normal">&#x0025;</mml:mi></mml:math> for Haar-random and permutation matrices, respectively, an optical loss of 2.9 dB averaged over all modes, and high-visibility quantum interference with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>V</mml:mi><mml:mrow class="MJX-TeXAtom-ORD"><mml:mtext>HOM</mml:mtext></mml:mrow></mml:msub><mml:mo>=</mml:mo><mml:mn>98</mml:mn><mml:mi mathvariant="normal">&#x0025;</mml:mi></mml:math>. The processor is realized in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow class="MJX-TeXAtom-ORD"><mml:mi mathvariant="normal">S</mml:mi><mml:msub><mml:mi mathvariant="normal">i</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">N</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:mrow></mml:math> waveguides and is actively cooled by a Peltier element.