Quantum computation and quantum simulation

Integrated waveguide network

Multi-photon source

Efficient in/out coupling and detection stage

Over the last years photonic quantum systems have become one of the most mature approaches for quantum computation and quantum simulation. Our group has been contributing to this development since the beginning, for example with the simulation of frustrated solid-state spin systems, the demonstration of blind quantum computing, the implementation of interactive-proofs for the verification of quantum computers and with the demonstration of speed-ups for quantum computations by superimposing the order of quantum gates . We have also contributed to the capability of processing multi-photon states using integrated waveguides. This allowed us to realize a Boson Sampling computation as one of the most resource-efficient quantum computation concepts. For scaling up photonic quantum computers we are also focusing on the development of novel quantum photonic technology, reaching from bright multi-photon sources and superconducting single-photon nanowire detectors to integrated waveguide structures as well as nonlinear media for photon-photon interactions and semiconductor single-photon sources.


Publications (selected):

Experimental quantum speed-up in reinforcement learning agents
V. Saggio, B.E. Asenbeck, A. Hamann, T. Strömberg, P. Schiansky, V. Dunjko, N. Friis, N.C. Harris, M. Hochberg, D. Englund, S. Wölk, H. J. Briegel, P. Walther,
Nature 591, 229–233 (2021).

Experimental few-copy multipartite entanglement detection
V. Saggio, A. Dimić, C. Greganti, L. A. Rozema, P. Walther, B. Dakić
Nature Physics, 24 June (2019).

Integrated-optics heralded controlled-NOT gate for polarization-encoded qubits
J. Zeuner, A.N. Sharma, M. Tillmann, R. Heilmann, M. Gräfe, A. Moqanaki, A. Szameit, P. Walther
npj Quantum Information 4, 13 (2018).

On unitary reconstruction of linear optical networks
M. Tillmann, C. Schmidt, P. Walther
Journal of Optics, 18,  4002 (2016).

Generalized Multiphoton Quantum Interference
M. Tillmann, S.-H. Tan, S.E. Stoeckl, B.C. Sanders, H. de Guise, R. Heilmann, S. Nolte, A. Szameit, P. Walther
Physical Review X 5, 041015 (2015).

Linear-optical generation of eigenstates of the two-site XY model
S. Barz, B. Dakic, Y.-O. Lipp, F. Verstraete, J.D. Whitfield, P. Walther
Physical Review X 5, 021010 (2015).

Experimental verification of quantum computation
S. Barz, J.F. Fitzsimons, E. Kashefi, P. Walther
Nature Physics 9, 727-731 (2013).

Experimental Boson Sampling
M. Tillmann, B. Dakic, R. Heilmann, S. Nolte, A. Szameit, P. Walther
Nature Photonics 7, 540-544 (2013).

Photonic quantum simulators
A. Aspuru-Guzik, P. Walther
Nature Physics 8, 285-291 (2012).

Demonstration of blind quantum computing
S. Barz, E. Kashefi, A. Broadbent, J. Fitzsimons, A. Zeilinger, P. Walther
Science 335, 303-308 (2012).


Further publications...