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7 results on '"Gildert, S."'

1. Probing High Frequency Noise with Macroscopic Resonant Tunneling

Author

Lanting, T., Amin, M. H. S., Johnson, M. W., Altomare, F., Berkley, A. J., Gildert, S., Harris, R., Johansson, J., Bunyk, P., Ladizinsky, E., Tolkacheva, E., and Averin, D. V.

Subjects
Condensed Matter - Superconductivity
Abstract

We have developed a method for extracting the high-frequency noise spectral density of an rf-SQUID flux qubit from macroscopic resonant tunneling (MRT) rate measurements. The extracted noise spectral density is consistent with that of an ohmic environment up to frequencies ~ 4 GHz. We have also derived an expression for the MRT lineshape expected for a noise spectral density consisting of such a broadband ohmic component and an additional strongly peaked low-frequency component. This hybrid model provides an excellent fit to experimental data across a range of tunneling amplitudes and temperatures.

Published
2011
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2. Observation of Co-tunneling in Pairs of Coupled Flux Qubits

Author

Lanting, T., Harris, R., Johansson, J., Amin, M. H. S., Berkley, A. J., Gildert, S., Johnson, M. W., Bunyk, P., Tolkacheva, E., Ladizinsky, E., Ladizinsky, N., Oh, T., Perminov, I., Chapple, E. M., Enderud, C., Rich, C., Wilson, B., Thom, M. C., Uchaikin, S., and Rose, G.

Subjects
Condensed Matter - Superconductivity
Abstract

We report measurements of macroscopic resonant tunneling between the two lowest energy states of a pair of magnetically coupled rf-SQUID flux qubits. This technique provides a direct means of observing two-qubit dynamics and a probe of the environment coupled to the pair of qubits. Measurements of the tunneling rate as a function of qubit flux bias show a Gaussian line shape that is well matched to theoretical predictions. Moreover, the peak widths indicate that each qubit is coupled to a local environment whose fluctuations are uncorrelated with that of the other qubit., Comment: 4 pages, 5 figures

Published
2010
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3. Quantum annealing with manufactured spins

Author

Johnson, M.W., Amin, M.H.S., Gildert, S., Lanting, T., Hamze, F., Dickson, N., Harris, R., Berkley, A.J., Johansson, J., Bunyk, P., Chapple, E.M., Enderud, C., Hilton, J.P., Karimi, K., Ladizinsky, E., Ladizinsky, N., Oh, T., Perminov, I., Rich, C., Thom, M.C., Tolkacheva, E., Truncik, C.J.S., Uchaikin, S., Wang, J., Wilson, B., and Rose, G.

Subjects
Superconductors -- Usage, Spin coupling -- Research, Algorithms -- Usage, Algorithm, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Many interesting but practically intractable problems can be reduced to that of finding the ground state of a system of interacting spins; however, finding such a ground state remains computationally difficult (1). It is believed that the ground state of some naturally occurring spin systems can be effectively attained through a process called quantum annealing (2,3). If it could be harnessed, quantum annealing might improve on known methods for solving certain types of problem (4,5). However, physical investigation of quantum annealing has been largely confined to microscopic spins in condensed-matter systems (6-12). Here we use quantum annealing to find the ground state of an artificial Ising spin system comprising an array of eight superconducting flux quantum bits with programmable spin-spin couplings. We observe a clear signature of quantum annealing, distinguishable from classical thermal annealing through the temperature dependence of the time at which the system dynamics freezes. Our implementation can be configured in situ to realize a wide variety of different spin networks, each of which can be monitored as it moves towards a low-energy configuration (13,14). This programmable artificial spin network bridges the gap between the theoretical study of ideal isolated spin networks and the experimental investigation of bulk magnetic samples. Moreover, with an increased number of spins, such a system may provide a practical physical means to implement a quantum algorithm, possibly allowing more-effective approaches to solving certain classes of hard combinatorial optimization problems., Physically interesting in their own right, systems of interacting spins also have practical importance for quantum computation (15). One widely studied example is the Ising spin model, where spins may [...]

Published
2011
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4. Thermally assisted quantum annealing of a 16-qubit problem

Author

Dickson, N G, primary, Johnson, M W, additional, Amin, M H, additional, Harris, R, additional, Altomare, F, additional, Berkley, A J, additional, Bunyk, P, additional, Cai, J, additional, Chapple, E M, additional, Chavez, P, additional, Cioata, F, additional, Cirip, T, additional, deBuen, P, additional, Drew-Brook, M, additional, Enderud, C, additional, Gildert, S, additional, Hamze, F, additional, Hilton, J P, additional, Hoskinson, E, additional, Karimi, K, additional, Ladizinsky, E, additional, Ladizinsky, N, additional, Lanting, T, additional, Mahon, T, additional, Neufeld, R, additional, Oh, T, additional, Perminov, I, additional, Petroff, C, additional, Przybysz, A, additional, Rich, C, additional, Spear, P, additional, Tcaciuc, A, additional, Thom, M C, additional, Tolkacheva, E, additional, Uchaikin, S, additional, Wang, J, additional, Wilson, A B, additional, Merali, Z, additional, and Rose, G, additional

Published
2013
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5. Probing high-frequency noise with macroscopic resonant tunneling

Author

Lanting, T., primary, Amin, M. H. S., additional, Johnson, M. W., additional, Altomare, F., additional, Berkley, A. J., additional, Gildert, S., additional, Harris, R., additional, Johansson, J., additional, Bunyk, P., additional, Ladizinsky, E., additional, Tolkacheva, E., additional, and Averin, D. V., additional

Published
2011
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6. Cotunneling in pairs of coupled flux qubits

Author

Lanting, T., primary, Harris, R., additional, Johansson, J., additional, Amin, M. H. S., additional, Berkley, A. J., additional, Gildert, S., additional, Johnson, M. W., additional, Bunyk, P., additional, Tolkacheva, E., additional, Ladizinsky, E., additional, Ladizinsky, N., additional, Oh, T., additional, Perminov, I., additional, Chapple, E. M., additional, Enderud, C., additional, Rich, C., additional, Wilson, B., additional, Thom, M. C., additional, Uchaikin, S., additional, and Rose, G., additional

Published
2010
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