Photonic Quantum Computing
Abstract:
Quantum physics has revolutionized our understanding of
information processing and enables computational speed-ups that are
unattainable using classical computers. In this talk I will present a
series of experiments in the field of photonic quantum computing. The
first experiment is in the field of photonic state engineering and
realizes the generation of heralded polarization-entangled photon
pairs [1]. It overcomes the limited applicability of photon-based
schemes for quantum information processing tasks, which arises from
the probabilistic nature of photon generation. The second experiment
uses polarization-entangled photonic qubits to implement blind
quantum computing, a new concept in quantum computing [2, 3]. Blind
quantum computing enables a nearly-classical client to access the
resources of a more computationally-powerful quantum server without
divulging the content of the requested computation. A third
experiment shows how the concept of blind quantum computing can be
applied to the field of verification. A new method is developed and
experimentally demonstrated to verify the correctness and the
entangling capabilities of a quantum computer [4]. Finally, I will
present an experiment realizing a measured universal two-qubit
photonic quantum processor by applying two consecutive CNOT gates to
the same pair of polarization-encoded qubits. To demonstrate the
flexibility of our system, we implement various instances of the
quantum algorithm for the solving of systems of linear equations [5].
[1] S. Barz, G. Cronenberg, A. Zeilinger, and P. Walther, Nature
Photonics 4, 553 (2010)
[2] A. Broadbent, J. Fitzsimons and E. Kashefi, in Proceedings of the
50th Annual Symposium on Foundations of Computer Science, 517 (2009)
[3] S. Barz, E. Kashefi, A. Broadbent, J. Fitzsimons, A. Zeilinger,
and P. Walther, Science 335, 303 (2012)
[4] S. Barz, J. Fitzsimons, E. Kashefi, and P. Walther, Nature
Physics, AOP, DOI: 10.1038/nphys2763 (2013)
[5] S. Barz, I. Kassal, M. Ringbauer, Y. O. Lipp, B. Dakic, A.
Aspuru-Guzik, P. Walther, arXiv:1302.1210