IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Jochen Braumüller1 , Andre Schneider1 and Martin P. Weides1,2 1Karlsruhe Institute of Technology (KIT) 2Johannes Gutenberg University Mainz September 29th 2015, Burg Warberg, Kryo 2015 Experiments with superconducting qubits multi-photon dressing, qubits with magnetic coupling IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Introduction . Anharmonic many-level quantum circuit . Dispersive shifts, power spectroscopy, Rabi sidebands . Concentric transmons . Gradiometric, fast tunable, site-selective sz coupling . Ongoing . QuantumMagnonics: quantum limited detection of dynamics in ferromagnets 2 Martin Weides KIT & JGU Mainz IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Bits and Quantum Bits Today’s chips Integrated circuit Classical bit 1-4 GHz clock rate Multi-core processsor 1 1 0 1 1 0 1st transistor 1947 Quantum bit (qubit) S = 1/2 Superposition & entanglement: 2N- dim. Hilbert space Parallel processing (Shor factoring, Grover search, Q-simulation) 3 Martin Weides KIT & JGU Mainz IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Transmons: capacitively shunted Josephson junction Anharmonic oscillator Non-linear, tunable LC oscillator Two lowest levels Bloch sphere Magnetic flux changes LJ(f) 4 Martin Weides KIT & JGU Mainz IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Introduction . Anharmonic many-level quantum circuit . Dispersive shifts, power spectroscopy, Rabi sidebands . Concentric transmons . Gradiometric, fast tunable, site-selective sz coupling . Ongoing . QuantumMagnonics: quantum limited detection of dynamics in ferromagnets 5 Martin Weides KIT & JGU Mainz IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Anharmonic many-level quantum circuit transmon qubit: weak anharmonicity Consider higher quantum levels efficient & robust enhanced security of key quantum quantum gates distribution in quantum simulation cryptography spin-½ ↔ two levels spin-1 ↔ three levels Neeley Nat. Phys. 4, 523 (2008) Bruß PRL 88, 127901 (2002) Paraoanu JLTP 175, 633 (2014) Fedorov Nat. 481, 170 (2011) Cerf PRL 88, 127902 (2002) 6 Martin Weides KIT & JGU Mainz IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Experiment . microstrip geometry Sandberg et al. APL 102, 072601 (2013) . overlap Josephson junction . transmon regime: ≫ ⇒ ~0.05 Koch et al. PRA 76, 042319 (2007) . spectroscopic measurements Blais et al. PRA 69, 062320 (2004) . VNA readout tone . microwave drive/probe tone Braumüller et al.,PRB 91, 7 Martin Weides KIT & JGU Mainz 054523 (2015) IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Power spectroscopy – multiphoton transitions Braumüller et al.,PRB 91, 8 Martin Weides KIT & JGU Mainz 054523 (2015) IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Power spectroscopy – multiphoton transitions Multi-photon transitions . Six bound states in Josephson potential . Dispersive shift scales with excitation number ‹n› Braumüller et al.,PRB 91, 9 Martin Weides KIT & JGU Mainz 054523 (2015) IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Dispersive shift by higher levels effective Hamiltonian Induced by resonator Induced by qubit Braumüller et al.,PRB 91, 10 Martin Weides KIT & JGU Mainz 054523 (2015) IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Dispersive shift by higher levels Rotating-wave Hamiltonian Induced by resonator Induced by qubit Spectroscopy: equal population of 0 , * Relative resonator shift c 0j 2 | ) w ( 21 |S g01 = 115 MHz D≈1 GHz Braumüller et al.,PRB 91, 11 Martin Weides KIT & JGU Mainz 054523 (2015) IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Power spectroscopy – data & simulation measurement simulation Braumüller et al.,PRB 91, 12 Martin Weides KIT & JGU Mainz 054523 (2015) IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Multiphoton dressing − , Rabi sidebands Strong drive Sweep drive amp, probe freq. measurement simulation . 0 , 2 degenerate in rotating frame dressing . Probing level structure (in rotating frame) with weak probe tone Braumüller et al.,PRB 91, 13 Martin Weides KIT & JGU Mainz 054523 (2015) IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Multiphoton dressing – pumping the |⟩-level Sweep drive & probe freqs. measurement simulation Dynamical coupling of levels by probe tone avoided crossing, Autler-Townes doublet Braumüller et al.,PRB 91, 14 Martin Weides KIT & JGU Mainz 054523 (2015) IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Introduction . Anharmonic many-level quantum circuit . Dispersive shifts, power spectroscopy, Rabi sidebands . Concentric transmons . Gradiometric, fast tunable, site-selective sz coupling . Ongoing . QuantumMagnonics: quantum limited detection of dynamics in ferromagnets 15 Martin Weides KIT & JGU Mainz IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Advancing coherence in superconducting qubits Devoret, Schoelkopf Science 339, 116 (2013) . Long coherence: scalable quantum computation, error correction . Useful: high experimental flexibility by fast flux tuning of levels 16 Martin Weides KIT & JGU Mainz IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Novel design: Tunable, concentric transmon qubit (2d) Coherence limited by energy relaxation . Minimize surface/interface TLS loss microstrip design . radiative decay reduce qubit‘s dipole moment (symmetry) . Fast (ns) tunability . Side-selective sz and sx couplings 17 Martin Weides KIT & JGU Mainz Braumüller et al., arXiv:1509.08014 IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Concentric transmon qubit – flux spectroscopy EJ, EC do not match conventional transmon theory Koch et al. PRA 76, 042319 (2007) Modified Hamiltonian considering geometric inductance 18 Martin Weides KIT & JGU Mainz Braumüller et al., arXiv:1509.08014 IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Pulsed measurements – Rabi oscillations ) . |0〉 a.u 11 ( arg |1〉 D () 19 Martin Weides KIT & JGU Mainz Braumüller et al., arXiv:1509.08014 IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Pulsed measurements – Lifetime and coherence P1 P0 echo T2=10.2 s T1=9.1 s P0 P1 0 10 20 30 0 10 20 30 Dt [s] Dt [s] 20 Martin Weides KIT & JGU Mainz Braumüller et al., arXiv:1509.08014 IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Pulsed measurements – fast z (energy splitting)-control 21 Martin Weides KIT & JGU Mainz Braumüller et al., arXiv:1509.08014 IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. XYZ-tomography, benchmarking, state control Full sx,sy,sz control, SSB-mixing, shaped pulses (DRAG) Gate benchmarking (99.54%) Precise qubit state control Monitor decay = (|0〉 + |1〉) (x-axis) 22 Martin Weides KIT & JGU Mainz Schneider MA thesis (2015) IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. XYZ-tomography, benchmarking, state control Full sx,sy,sz control, SSB-mixing, shaped pulses (DRAG) Gate benchmarking (99.54%) Precise qubit state control Monitor decay = (|0〉 + |1〉) (x-axis) 23 Martin Weides KIT & JGU Mainz Schneider MA thesis (2015) IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. XYZ-tomography, benchmarking, state control Full sx,sy,sz control, SSB-mixing, shaped pulses (DRAG) Gate benchmarking (99.54%) Precise qubit state control Monitor decay = (|〉 + |〉) (x-axis) 24 Martin Weides KIT & JGU Mainz Schneider MA thesis (2015) IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016. KRYO 2015 oral presentation. Not submitted for publication. Introduction . Anharmonic many-level quantum circuit . Dispersive shifts, power spectroscopy, Rabi sidebands . Concentric