Demonstration of universal parametric entangling gates on a multi-qubit lattice

• Published in: Science advances 2018-02, Vol.4 (2), p.eaao3603-eaao3603
• Main Authors: Reagor, Matthew, Osborn, Christopher B, Tezak, Nikolas, Staley, Alexa, Prawiroatmodjo, Guenevere, Scheer, Michael, Alidoust, Nasser, Sete, Eyob A, Didier, Nicolas, da Silva, Marcus P, Acala, Ezer, Angeles, Joel, Bestwick, Andrew, Block, Maxwell, Bloom, Benjamin, Bradley, Adam, Bui, Catvu, Caldwell, Shane, Capelluto, Lauren, Chilcott, Rick, Cordova, Jeff, Crossman, Genya, Curtis, Michael, Deshpande, Saniya, El Bouayadi, Tristan, Girshovich, Daniel, Hong, Sabrina, Hudson, Alex, Karalekas, Peter, Kuang, Kat, Lenihan, Michael, Manenti, Riccardo, Manning, Thomas, Marshall, Jayss, Mohan, Yuvraj, O'Brien, William, Otterbach, Johannes, Papageorge, Alexander, Paquette, Jean-Philip, Pelstring, Michael, Polloreno, Anthony, Rawat, Vijay, Ryan, Colm A, Renzas, Russ, Rubin, Nick, Russel, Damon, Rust, Michael, Scarabelli, Diego, Selvanayagam, Michael, Sinclair, Rodney, Smith, Robert, Suska, Mark, To, Ting-Wai, Vahidpour, Mehrnoosh, Vodrahalli, Nagesh, Whyland, Tyler, Yadav, Kamal, Zeng, William, Rigetti, Chad T
• Format: Article
• Language: English
• Subjects: Applied Sciences and Enigineering; Physics; SciAdv r-articles
• ISSN: 2375-2548; 2375-2548
• DOI: 10.1126/sciadv.aao3603

We show that parametric coupling techniques can be used to generate selective entangling interactions for multi-qubit processors. By inducing coherent population exchange between adjacent qubits under frequency modulation, we implement a universal gate set for a linear array of four superconducting qubits. An average process fidelity of ℱ = 93% is estimated for three two-qubit gates via quantum process tomography. We establish the suitability of these techniques for computation by preparing a four-qubit maximally entangled state and comparing the estimated state fidelity with the expected performance of the individual entangling gates. In addition, we prepare an eight-qubit register in all possible bitstring permutations and monitor the fidelity of a two-qubit gate across one pair of these qubits. Across all these permutations, an average fidelity of ℱ = 91.6 ± 2.6% is observed. These results thus offer a path to a scalable architecture with high selectivity and low cross-talk.