Browsing by Author "Nakamura, Y."

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Advances in Magnetics Roadmap on Spin-Wave Computing
(2022-06) Chumak, A. V.; Kabos, P.; Wu, M.; Abert, C.; Adelmann, C.; Adeyeye, A.; Akerman, J.; Aliev, F. G.; Anane, A.; Awad, A.; Back, C. H.; Barman, A.; Bauer, G. E.W.; Becherer, M.; Beginin, E. N.; Bittencourt, V. A.S.V.; Blanter, Y. M.; Bortolotti, P.; Boventer, I.; Bozhko, D. A.; Bunyaev, S. A.; Carmiggelt, J. J.; Cheenikundil, R. R.; Ciubotaru, F.; Cotofana, S.; Csaba, G.; Dobrovolskiy, O. V.; Dubs, C.; Elyasi, M.; Fripp, K. G.; Fulara, H.; Golovchanskiy, I. A.; Gonzalez-Ballestero, C.; Graczyk, P.; Grundler, D.; Gruszecki, P.; Gubbiotti, G.; Guslienko, K.; Haldar, A.; Hamdioui, S.; Hertel, R.; Hillebrands, B.; Hioki, T.; Houshang, A.; Hu, C. M.; Huebl, H.; Huth, M.; Iacocca, E.; Jungfleisch, M. B.; Kakazei, G. N.; Khitun, A.; Khymyn, R.; Kikkawa, T.; Klaui, M.; Klein, O.; Klos, J. W.; Knauer, S.; Koraltan, S.; Kostylev, M.; Krawczyk, M.; Krivorotov, I. N.; Kruglyak, V. V.; Lachance-Quirion, D.; Ladak, S.; Lebrun, R.; Li, Y.; Lindner, M.; Macedo, R.; Mayr, S.; Melkov, G. A.; Mieszczak, S.; Nakamura, Y.; Nembach, H. T.; Nikitin, A. A.; Nikitov, S. A.; Novosad, V.; Otalora, J. A.; Otani, Y.; Papp, A.; Pigeau, B.; Pirro, P.; Porod, W.; Porrati, F.; Qin, H.; Rana, B.; Reimann, T.; Riente, F.; Romero-Isart, O.; Ross, A.; Sadovnikov, A. V.; Safin, A. R.; Saitoh, E.; Schmidt, G.; Schultheiss, H.; Schultheiss, K.; Serga, A. A.; Sharma, S.; Shaw, Justin M.; Suess, D.; Surzhenko, O.; Szulc, K.; Taniguchi, T.; Urbanek, M.; Usami, K.; Ustinov, A. B.; Van der Sar, T.; Van Dijken, S.; Vasyuchka, V. I.; Verba, R.; Viola Kusminskiy, S.; Wang, Qi; Weides, M.; Weiler, Mathias; Wintz, S.; Wolski, S. P.; Zhang, X.
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Magnonics addresses the physical properties of spin waves and utilizes them for data processing. Scalability down to atomic dimensions, operation in the GHz-to-THz frequency range, utilization of nonlinear and nonreciprocal phenomena, and compatibility with CMOS are just a few of many advantages offered by magnons. Although magnonics is still primarily positioned in the academic domain, the scientific and technological challenges of the field are being extensively investigated, and many proof-of-concept prototypes have already been realized in laboratories. This roadmap is a product of the collective work of many authors, which covers versatile spin-wave computing approaches, conceptual building blocks, and underlying physical phenomena. In particular, the roadmap discusses the computation operations with the Boolean digital data, unconventional approaches, such as neuromorphic computing, and the progress toward magnon-based quantum computing. This article is organized as a collection of sub-sections grouped into seven large thematic sections. Each sub-section is prepared by one or a group of authors and concludes with a brief description of current challenges and the outlook of further development for each research direction.
Dephasing and dissipation in qubit thermodynamics
(2015-06-08) Pekola, J. P.; Masuyama, Y.; Nakamura, Y.; Bergli, J.; Galperin, Y.M.
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
We analyze the stochastic evolution and dephasing of a qubit within the quantum jump approach. It allows one to treat individual realizations of inelastic processes, and in this way it provides solutions, for instance, to problems in quantum thermodynamics and distributions in statistical mechanics. We demonstrate that dephasing and relaxation of the qubit render the Jarzynski and Crooks fluctuation relations (FRs) of nonequilibrium thermodynamics intact. On the contrary, the standard two-measurement protocol, taking into account only the fluctuations of the internal energy U, leads to deviations in FRs under the same conditions. We relate the average ⟨e−βU⟩ (where β is the inverse temperature) with the qubit's relaxation and dephasing rates in the weak dissipation limit and discuss this relationship for different mechanisms of decoherence.
Detection of mechanical resonance of a single-electron transistor by direct current
(2010) Pashkin, Yu. A.; Li, T. F.; Pekola, Jukka P.; Astafiev, O.; Knyazev, D. A.; Hoehne, F.; Im, H.; Nakamura, Y.; Tsai, J. S.
School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
We have suspended an Al based single-electron transistor (SET) whose island can resonate freely between the source and drain leads forming the clamps. In addition to the regular side gate, a bottom gate with a larger capacitance to the SET island is placed underneath to increase the SET coupling to mechanical motion. The device can be considered as a doubly clamped Al beam that can transduce mechanical vibrations into variations in the SET current. Our simulations based on the orthodox model, with the SET parameters estimated from the experiment, reproduce the observed transport characteristics in detail.
Information entrope superconducting microcooler
(2007-11-29) Niskanen, A. O.; Nakamura, Y.; Pekola, Jukka
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
We consider a design for a cyclic microrefrigerator using a superconducting flux qubit. Adiabatic modulation of the flux combined with thermalization can be used to transfer energy from a lower temperature normal metal thin film resistor to another one at higher temperature. The frequency selectivity of photonic heat conduction is achieved by including the hot resistor as part of a high frequency LC resonator and the cold one as part of a low-frequency oscillator while keeping both circuits in the underdamped regime. We discuss the performance of the device in an experimentally realistic setting. This device illustrates the complementarity of information and thermodynamic entropy as the erasure of the quantum bit directly relates to the cooling of the resistor.
Information entropic superconducting microcooler
(2007) Niskanen, A. O.; Nakamura, Y.; Pekola, Jukka P.
School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
We consider a design for a cyclic microrefrigerator using a superconducting flux qubit. Adiabatic modulation of the flux combined with thermalization can be used to transfer energy from a lower temperature normal metal thin film resistor to another one at higher temperature. The frequency selectivity of photonic heat conduction is achieved by including the hot resistor as part of a high frequency LC resonator and the cold one as part of a low-frequency oscillator while keeping both circuits in the underdamped regime. We discuss the performance of the device in an experimentally realistic setting. This device illustrates the complementarity of information and thermodynamic entropy as the erasure of the quantum bit directly relates to the cooling of the resistor.