biostudies-literatureBarz SAustrian Science Fund FWF6115https://www.ebi.ac.uk/biostudies/studies/S-EPMC4137340biostudies-literatureUnknown4Large-scale quantum computers will require the ability to apply long sequences of entangling gates to many qubits. In a photonic architecture, where single-qubit gates can be performed easily and precisely, the application of consecutive two-qubit entangling gates has been a significant obstacle. Here, we demonstrate a two-qubit photonic quantum processor that implements two consecutive CNOT gates on the same pair of polarisation-encoded qubits. To demonstrate the flexibility of our system, we implement various instances of the quantum algorithm for solving of systems of linear equations.Scientific reportsA two-qubit photonic quantum processor and its application to solving systems of linear equations.PMC4137340I 754Y 585Walther PBarz SDakic BAspuru-Guzik ARingbauer MLipp YOKassal IfalseA two-qubit photonic quantum processor and its application to solving systems of linear equations.Large-scale quantum computers will require the ability to apply long sequences of entangling gates to many qubits. In a photonic architecture, where single-qubit gates can be performed easily and precisely, the application of consecutive two-qubit entangling gates has been a significant obstacle. Here, we demonstrate a two-qubit photonic quantum processor that implements two consecutive CNOT gates on the same pair of polarisation-encoded qubits. To demonstrate the flexibility of our system, we implement various instances of the quantum algorithm for solving of systems of linear equations.2014-01-01T00:00:00Z2014 Aug2025-04-22T16:53:10.689Z2019-03-27T01:34:19ZS-EPMC41373402513543210.1038/srep06115