Barz, StefanieKassal, IvanRingbauer, MartinLipp, Yannick OleDakić, BorivojeAspuru-Guzik, AlanWalther, Philip2014-09-082014Barz, Stefanie, Ivan Kassal, Martin Ringbauer, Yannick Ole Lipp, Borivoje Dakić, Alán Aspuru-Guzik, and Philip Walther. 2014. “A two-qubit photonic quantum processor and its application to solving systems of linear equations.” Scientific Reports 4 (1): 6115. doi:10.1038/srep06115. http://dx.doi.org/10.1038/srep06115.2045-2322http://nrs.harvard.edu/urn-3:HUL.InstRepos:12785850Large-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.en-USJournal Article2014-09-0810.1038/srep06115