01523nas a2200205 4500008004100000245004800041210004500089260001500134300001200149490000800161520099800169100001101167700001501178700001301193700001801206700001901224700001901243700001801262856003701280 2018 eng d00aA Coherent Spin-Photon Interface in Silicon0 aCoherent SpinPhoton Interface in Silicon c2018/03/29 a599-6030 v5553 a

Electron spins in silicon quantum dots are attractive systems for quantum computing due to their long coherence times and the promise of rapid scaling using semiconductor fabrication techniques. While nearest neighbor exchange coupling of two spins has been demonstrated, the interaction of spins via microwave frequency photons could enable long distance spin-spin coupling and "all-to-all" qubit connectivity. Here we demonstrate strong-coupling between a single spin in silicon and a microwave frequency photon with spin-photon coupling rates g_s/(2π) > 10 MHz. The mechanism enabling coherent spin-photon interactions is based on spin-charge hybridization in the presence of a magnetic field gradient. In addition to spin-photon coupling, we demonstrate coherent control of a single spin in the device and quantum non-demolition spin state readout using cavity photons. These results open a direct path toward entangling single spins using microwave frequency photons.

1 aMi, X.1 aBenito, M.1 aPutz, S.1 aZajac, D., M.1 aTaylor, J., M.1 aBurkard, Guido1 aPetta, J., R. uhttps://arxiv.org/abs/1710.0326501974nas a2200181 4500008004100000245005000041210004800091260001500139520145800154100001101612700001501623700001301638700001801651700001901669700001901688700001801707856006701725 2018 eng d00aA coherent spin–photon interface in silicon0 acoherent spin–photon interface in silicon c2018/02/143 a

Electron spins in silicon quantum dots are attractive systems for quantum computing owing to their long coherence times and the promise of rapid scaling of the number of dots in a system using semiconductor fabrication techniques. Although nearest-neighbour exchange coupling of two spins has been demonstrated, the interaction of spins via microwave-frequency photons could enable long-distance spin–spin coupling and connections between arbitrary pairs of qubits (‘all-to-all’ connectivity) in a spin-based quantum processor. Realizing coherent spin–photon coupling is challenging because of the small magnetic-dipole moment of a single spin, which limits magnetic-dipole coupling rates to less than 1 kilohertz. Here we demonstrate strong coupling between a single spin in silicon and a single microwave-frequency photon, with spin–photon coupling rates of more than 10 megahertz. The mechanism that enables the coherent spin–photon interactions is based on spin–charge hybridization in the presence of a magnetic-field gradient. In addition to spin–photon coupling, we demonstrate coherent control and dispersive readout of a single spin. These results open up a direct path to entangling single spins using microwave-frequency photons.

1 aMi, X.1 aBenito, M.1 aPutz, S.1 aZajac, D., M.1 aTaylor, J., M.1 aBurkard, Guido1 aPetta, J., R. uhttps://www.nature.com/articles/nature25769#author-information01662nas a2200217 4500008004100000245004300041210004300084260001500127300001100142490000600153520108300159100001601242700001501258700001601273700001901289700001101308700002101319700001901340700001801359856006701377 2016 eng d00aDouble Quantum Dot Floquet Gain Medium0 aDouble Quantum Dot Floquet Gain Medium c2016/11/07 a0410270 v63 a

Strongly driving a two-level quantum system with light leads to a ladder of Floquet states separated by the photon energy. Nanoscale quantum devices allow the interplay of confined electrons, phonons, and photons to be studied under strong driving conditions. Here we show that a single electron in a periodically driven DQD functions as a "Floquet gain medium," where population imbalances in the DQD Floquet quasi-energy levels lead to an intricate pattern of gain and loss features in the cavity response. We further measure a large intra-cavity photon number n_c in the absence of a cavity drive field, due to equilibration in the Floquet picture. Our device operates in the absence of a dc current -- one and the same electron is repeatedly driven to the excited state to generate population inversion. These results pave the way to future studies of non-classical light and thermalization of driven quantum systems.

1 aStehlik, J.1 aLiu, Y.-Y.1 aEichler, C.1 aHartke, T., R.1 aMi, X.1 aGullans, Michael1 aTaylor, J., M.1 aPetta, J., R. uhttp://journals.aps.org/prx/abstract/10.1103/PhysRevX.6.041027