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Quantum computing experiments are moving into a new realm of increasing size and complexity, with the short-term goal of demonstrating an advantage over classical computers. Boson sampling is a promising platform for such a goal; however, the number of detected single photons is up to five so far, limiting these small-scale implementations to a proof-of-principle stage. Here, we develop solid-state sources of highly efficient, pure, and indistinguishable single photons and 3D integration of ultralow-loss optical circuits. We perform experiments with 20 pure single photons fed into a 60-mode interferometer. In the output, we detect up to 14 photons and sample over Hilbert spaces with a size up to 3.7×1014, over 10 orders of magnitude larger than all previous experiments, which for the first time enters into a genuine sampling regime where it becomes impossible to exhaust all possible output combinations. The results are validated against distinguishable samplers and uniform samplers with a confidence level of 99.9%. Publisher PDF

We thank C. Schneider for fruitful discussions and A. Clemens and K. Ostermann (TU Dresden, Germany) for technical support with protein preparation. We acknowledge financial support from the European Research Council (ERC StG ABLASE, 640012), the Scottish Funding Council (via SUPA), the European Union Marie Curie Career Integration Grant (PCIG12-GA-2012-334407) and the EPSRC Hybrid Polaritonics program grant (EP/M025330/1). M.S. acknowledges funding from the German Science Foundation (DFG) through a Research Fellowship (SCHU 3003/1-1) and from the European Commission for a Marie Sklodowska-Curie Individual Fellowship (659213). S.H. gratefully acknowledges support by the Royal Society and the Wolfson Foundation. Strong coupling between cavity photons and excited states of biologically produced recombinant fluorescent proteins in fully tunable optical microcavities is demonstrated. Natural thickness and concentration gradients in blends of two different proteins allow precise adjustment of the spectral position of polariton states and of the effective coupling strength, thus providing control of the photonic and excitonic components of the system. Publisher PDF

We acknowledge financial support by the State of Bavaria. Y.-M.H. acknowledges support from the Sino-German (CSC-DAAD) Postdoc Scholarship Program. This publication was funded by the German Research Foundation (DFG) and the University of Wuerzburg in the funding programme Open Access Publishing. We study trapped single excitons in a monolayer semiconductorwith respect to their temperature stability, spectral diffusion and decaydynamics. In a mechanically exfoliated WSe2 sheet, we could identifydiscrete emission features with emission energies down to 1.516 eV whichare spectrally isolated in a free spectral range up to 80 meV. The strongspectral isolation of our localized emitter allow us to identify strongsignatures of phonon induced spectral broadening for elevated temperaturesaccompanied by temperature induced luminescence quenching. A directcorrelation between the droop in intensity at higher temperatures with thephonon induced population of dark states in WSe2 is established. While ourexperiment suggests that the applicability of monolayered quantum emittersas coherent single photon sources at elevated temperatures may be limited,the capability to operate them below the GaAs band-edge makes themhighly interesting for GaAs-monolayer hybrid quantum photonic structures. Postprint

A.K. acknowledges the support from the EPSRC Established Career Fellowship. V.K., M.D., V.F.S. and A.K. acknowledge support from the Russian Ministry of Science and Education, contract (contract No. 11.G34.31.0067). P.G.S. acknowledges support from Greek GSRT program Aristeia (grant No. 1978). C.S., M. A. J.F., M.K and S.H. acknowledge support from the state of Bavaria. Light amplification by stimulated emission of radiation, well-known for revolutionising photonic science, has been realised primarily in fermionic systems including widely applied diode lasers. The prerequisite for fermionic lasing is the inversion of electronic population, which governs the lasing threshold. More recently, bosonic lasers have also been developed based on Bose-Einstein condensates of exciton-polaritons in semiconductor microcavities. These electrically neutral bosons coexist with charged electrons and holes. In the presence of magnetic fields, the charged particles are bound to their cyclotron orbits, while the neutral exciton-polaritons move freely. We demonstrate how magnetic fields affect dramatically the phase diagram of mixed Bose-Fermi systems, switching between fermionic lasing, incoherent emission and bosonic lasing regimes in planar and pillar microcavities with optical and electrical pumping. We collected and analyzed the data taken on pillar and planar microcavity structures at continuous wave and pulsed optical excitation as well as injecting electrons and holes electronically. Our results evidence the transition from a Bose gas to a Fermi liquid mediated by magnetic fields and light-matter coupling. Publisher PDF

The authors gratefully acknowledge expert sample preparation by M Emmerling and A Wolf as well as financial support by the German Ministry of Education and Research through the project QPENS and QUASAR. Highly efficient single-photon sources (SPS) can increase the secure key rate of quantum key distribution (QKD) systems compared to conventional attenuated laser systems. Here we report on a free space QKD test using an electrically driven quantum dot single-photon source (QD SPS) that does not require a separate laser setup for optical pumping and thus allows for a simple and compact SPS QKD system. We describe its implementation in our 500 m free space QKD system in downtown Munich. Emulating a BB84 protocol operating at a repetition rate of 125 MHz, we could achieve sifted key rates of 5-17 kHz with error ratios of 6-9% and g((2))(0)-values of 0.39-0.76. Publisher PDF