TY  - JOUR
A1  - Yu, Leo
A1  - Natarajan, Chandra M.
A1  - Horikiri, Tomoyuki
A1  - Langrock, Carsten
A1  - Pelc, Jason S.
A1  - Tanner, Michael G.
A1  - Abe, Eisuke
A1  - Maier, Sebastian
A1  - Schneider, Christian
A1  - Höfling, Sven
A1  - Kamp, Martin
A1  - Hadfield, Robert H.
A1  - Fejer, Martin M.
A1  - Yamamoto, Yoshihisa
T1  - Two-photon interference at telecom wavelengths for time-bin-encoded single photons from quantum-dot spin qubits
JF  - Nature Communications
N2  - Practical quantum communication between remote quantum memories rely on single photons at telecom wavelengths. Although spin-photon entanglement has been demonstrated in atomic and solid-state qubit systems, the produced single photons at short wavelengths and with polarization encoding are not suitable for long-distance communication, because they suffer from high propagation loss and depolarization in optical fibres. Establishing entanglement between remote quantum nodes would further require the photons generated from separate nodes to be indistinguishable. Here, we report the observation of correlations between a quantum-dot spin and a telecom single photon across a 2-km fibre channel based on time-bin encoding and background-free frequency downconversion. The downconverted photon at telecom wavelengths exhibits two-photon interference with another photon from an independent source, achieving a mean wavepacket overlap of greater than 0.89 despite their original wavelength mismatch (900 and 911 nm). The quantum-networking operations that we demonstrate will enable practical communication between solid-state spin qubits across long distances.
KW  - atom
KW  - 1550 nm
KW  - up-conversion
KW  - heralded entanglement
KW  - emission
KW  - interface
KW  - generation
KW  - communication
KW  - downconversion
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-138677
VL  - 6
ER  - 
TY  - JOUR
A1  - Horikiri, Tomoyuki
A1  - Yamaguchi, Makoto
A1  - Kamide, Kenji
A1  - Matsuo, Yasuhiro
A1  - Byrnes, Tim
A1  - Ishida, Natsuko
A1  - Löffler, Andreas
A1  - Höfling, Sven
A1  - Shikano, Yutaka
A1  - Ogawa, Tetsuo
A1  - Forchel, Alfred
A1  - Yamamoto, Yoshihisa
T1  - High-energy side-peak emission of exciton-polariton condensates in high density regime
JF  - Scientific Reports
N2  - In a standard semiconductor laser, electrons and holes recombine via stimulated emission to emit coherent light, in a process that is far from thermal equilibrium. Exciton-polariton condensates–sharing the same basic device structure as a semiconductor laser, consisting of quantum wells coupled to a microcavity–have been investigated primarily at densities far below the Mott density for signatures of Bose-Einstein condensation. At high densities approaching the Mott density, exciton-polariton condensates are generally thought to revert to a standard semiconductor laser, with the loss of strong coupling. Here, we report the observation of a photoluminescence sideband at high densities that cannot be accounted for by conventional semiconductor lasing. This also differs from an upper-polariton peak by the observation of the excitation power dependence in the peak-energy separation. Our interpretation as a persistent coherent electron-hole-photon coupling captures several features of this sideband, although a complete understanding of the experimental data is lacking. A full understanding of the observations should lead to a development in non-equilibrium many-body physics.
KW  - side-peak emission
KW  - exciton-polariton condensates
KW  - standard semiconductor laser
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-167711
VL  - 6
IS  - 25655
ER  -