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[1] Electrically driven nuclear spin resonance in single-molecule magnets. S. Thiele, F. Balestro, R. Balou, S. Klyatskaya, M. Ruben and W. Wernsdorfer Science 344, 1135 (2014).[2] Electronic read-out of a single nuclear spin using a molecular spin transistor. R. Vincent, S. Klyatskaya, M. Ruben and W. Wernsdorfer and F. Balestro Nature 488, 357 (2012).[3] Detection of a Large Valley-Orbit Splitting in Silicon with Two-Donor Spectroscopy. B. Roche, E. Dupont-Ferrier, B. Voisin, M. Cobian, X. Jehl, R. Wacquez, M. Vinet, Y.-M. Niquet, and M. Sanquer, Phys. Rev. Lett. 108, 206812 (2012).[4] Electrons surfing on a sound wave: an experimental platform for quantum optics with flying electrons. S. Hermelin, S. Takada, M. Yamamoto, S. Tarucha, A. D. Wieck, L. Saminadayar, C. Bauerle and T. Meunier, Nature (London) 447, 435 (2011).[5] Probing the Spin State of a Single Magnetic Ion in an individual Quantum Dot. L. Besombes, Y. Léger, L. Maingault, D. Ferrand, H.Mariette, and J. Cibert Phys. Rev. Lett. 93, 207403 (2004).[6] Dynamics of a Mn spin coupled to a single hole confined in a quantum dot. B. Varghese, H. Boukari, and L. Besombes, Phys. Rev. B 90, 115307 (2014).

Fig. 2: Split-gate field-effect transistor fabricated by CEA-LETI. The device consists of a 20-nm-thick, 60-nm-wide silicon-on-insulator channel (colorized in blue) with two face-to-face top gates (colorized in grey) defined by means of e-beam lithography. Individual electrons can be accumu-lated underneath each gate [3]. Their use as spin qubits is currently under investigation.

gate 1 gate 2

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Fig. 4: Photoluminescence at T=5K of a magnetic quantum dot containing a single Mn atom (electronic spin S=5/2) and a single heavy-hole (Jz=±3/2) and its energy spectrum [5]. We have demonstrated that an individual magnetic atom embedded in a semiconductor quantum dot may act as a spin-based memory [6]. We can exploit the optical absorp-tion and emission of the quantum dot in order to initialize and to read out the spin state of the magnetic atom.

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Fig. 1: A nuclear spin qubit transistor based on a single TbPc2 molecular magnet. The molecule, consisting of a Tb3+ ion (pink) sandwiched between two Pc-ligands (white), is coupled to source, drain, and gate (not shown) electrodes. The four anisotropic nuclear spin states of the Tb3+ (colored circles) can be tuned and manipulated with electric fields [1]. Nuclear spin state is detected via one-shot electronic read-out [2].

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Fig. 3: Single electron transport between two distant quan-tum dots, assisted by a sound wave. The two quantum dots, defined by the electrostatic gates coloured in magenta, are interconnected by a long ”quantum bus” (grey). A single electron, trapped initially in the left quantum dot, is propel-led by a sound wave towards the second quantum dot, at distance 3 microns [4]. It is considered as a possible way to transfer information in a spin-based quantum computation device.

Quantum Point Contact

Quantum Point Contact

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Fig. 1: Bright single-photon source based on a semi-conduc-ting quantum dot (QD) em-bedded in photonic wave-guide with tailored ends. This light collection strategy features an almost ideal one-dimensionnal geometry over a broad wave-length range, offering efficient light emission [1] and giant non-linearities [2].

Fig. 3: Hybrid mechanical systems are systems for which a mechanical oscillator is coupled to an individual quantum system. It can be an NV center in diamond at the tip of an oscillating nanowire immersed in a magnetic field gradient [4], or a quantum dot strain-coupled to a mechanical os-cillator [5]. Hybrid nanomechanical devices hold the pro-mise of mapping the “quantumness” of the qubit state onto the mechanical oscillator and therefore store quantum information.

[1] A highly efficient single-photon source based on a quantum dot in a photonic nanowire. J. Claudon, J. Bleuse, N. S. Malik, M. Bazin, P. Jaffrennou, N. Gregersen, C. Sauvan, P. Lalanne, and J. M. Gérard, Nature Photonics 4, 174 (2010).[2] Fabry-Perot Interferometer with Quantum Mirrors: Nonlinear Light Transport and Rectification. F. Fratini, E. Mascaren-has, L. Safari, J-Ph. Poizat, D. Valente, A. Auffèves, D. Gerace, and M. F. Santos, Phys. Rev. Lett. 113, 243601 (2014).[3] Quantum theory analysis of triple photons generated by a χ(3) process A. Dot, A. Borne, B. Boulanger, K. Bencheikh, and J.A. Levenson, Phys. Rev. A 85, 023809 (2012).[4] A single nitrogen-vacancy defect coupled to a nanomechanical oscillator. O. Arcizet, V. Jacques, A. Siria, P. Poncharal, P. Vincent, S. Seidelin, Nature Phys. 7, 879 (2011).[5] Strain-mediated coupling in a quantum dot-mechanical oscillator hybrid system. I. Yeo, P-L. de Assis, A. Gloppe, E. Dupont-Ferrier, P. Verlot, N. S. Malik, E. Dupuy, J. Claudon, J-M. Gérard, A. Auffèves, G. Nogues, S. Seidelin, J-Ph. Poizat, O. Arcizet and M. Richard, Nature Nano. 9, 106 (2014).[6] Quantum plasmonics: Second-order coherence of surface plasmons launched by quantum emitters into a metallic film. O. Mollet, S. Huant, G. Dantelle, T. Gacoin, and A. Drezet, Phys. Rev. B 86, 045401 (2012).[7] Fabrication and tuning of plasmonic optical nanoantennas around droplet epitaxy quantum dots by cathodolumines-cence. G. Nogues, Q. Merotto, G. Bachelier, E.H. Lee, and J.D. Song, Appl. Phys. Lett. 102, 231112 (2013).

Fig. 2 (a) Scheme of triple photons generation gover-ned by the third-order susceptibility χ(3) in a nonlinear medium [3]. Photons at frequencies ω1, ω2 and ω3 are created by the splitting of pump photons at frequency ω0. (b) Wigner function for a degenerate three-photon quantum state, i.e. ω1 = ω2 = ω3.

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PCFluorescence

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Fig. 4: Principle of quantum plasmonics using a diamond nanocrystal containing a single NV center at the tip of a near-field scanning optical microscope [6]. Individual sur-face plasmons (SP) are launched along a metal film and are recorded using leakage radiation microscopy. Other systems involve the fabrication and tuning of plasmonic optical na-noantennas around semiconductor quantum dots by catho-doluminescence [7].

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Fig. 2: Hybrid multi-terminal device towards a source of en-tangled electrons [3]: a piece of normal metal (copper) is connected to three superconducting contacts (aluminum). When the bias voltages Va and Vb compensate each other, new resonances appear in the low voltage conductance map which are consistent with prediction of quartets formed by the simultaneous splitting of two Cooper pairs at the upper superconducting contact and the emission of two phase cor-related Cooper pairs in the two other electrodes.

Fig. 4: Josephson circuit analog of the widely-sought Kondo screening cloud [5]: besides quantum computation, super-conducting qubits offer a way to engineer analog quantum simulators of complex condensed-matter problems in a controlled and tunable experimental setting. Anderson loca-lization and Kondo physics are two paradigmatic examples that could take place in carefully crafted arrays of Josephson junctions, as shown by theoretical groups in Grenoble. This could pave the way for the generation of high non-lineari-ties in the few photon limit and the detection of non-trivial many-body states.

Fig. 1: Two inductively coupled phase qubits. Due to a large inductor, this artificial atom contains a second degree of freedom leading to a V-shape energy diagram. In addition to the qubit transition, it enables an ancilla transition, leads to new quantum abilities such as coherent up and down conversion in time domain [1], and is predicted to lead to ultrafast high fidelity qubit read-out [2]. V-shape energy dia-gram was recently demonstrated in a two inductively coup-led transmons circuit.

[1] Coherent frequency conversion in a superconducting artificial atom with two internal degrees of freedom, F. Lecocq, I. M. Pop, I. Matei, E. Dumur, A. Feofanov, C. Naud, W. Guichard, and O. Buisson, Phys. Rev. Lett. 108, 107001 (2012).[2] Ultrafast QND measurements based on diamond-shape artificial atom. I. Diniz, E. Dumur, O. Buisson and A. Auffeves. Phys. Rev. A 87, 033837 (2013).[3] Subgap structure in the conductance of a three-terminal Josephson junction A. H. Pfeffer, J. E. Duvauchelle, H. Courtois, R. Mélin, D. Feinberg, and F. Lefloch, Physical Review B 90, 075401 (2014).[4] Spin-resolved Andreev levels and parity crossings in hybrid superconductor-semiconductor nanostructures E. J. H. Lee, X. Jiang, M. Houzet, R. Aguado, C. M. Lieber, and S. De Franceschi, Nature Nanotechnology 9, 79 (2014).[5] Stabilizing spin coherence through environmental entanglement in strongly dissipative quantum systems S. Bera, S. Florens, H. U. Baranger, N. Roch, A. Nazir, and A. W. Chin, Phys. Rev. B 89, 121108(R).

Fig. 3: Hybrid InAs-InP core-shell nanowire device for the study of sub-gap quasi-particle states [4]. The nanowire is contacted by superconducting electrode (S) and normal electrode (N). Three bottom gates (pg, sg and a back gate) create a quantum dot between N and S and tune its energy levels as well as the tunnel couplings to N and S. With this geometry, we have been able to reveal the splitting and crossing of the Andreev levels under magnetic field. The resulting zero-energy quasi-particle excitation bears some resemblance to Majorana fermions.

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