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Barends R, Quintana CM, Petukhov AG, Chen Y, Kafri D, Kechedzhi K, Collins R, Naaman O, Boixo S, Arute F, Arya K, Buell D, Burkett B, Chen Z, Chiaro B, Dunsworth A, Foxen B, Fowler A, Gidney C, Giustina M, Graff R, Huang T, Jeffrey E, Kelly J, Klimov PV, Kostritsa F, Landhuis D, Lucero E, McEwen M, Megrant A, Mi X, Mutus J, Neeley M, Neill C, Ostby E, Roushan P, Sank D, Satzinger KJ, Vainsencher A, White T, Yao J, Yeh P, Zalcman A, Neven H, Smelyanskiy VN, Martinis JM. Diabatic Gates for Frequency-Tunable Superconducting Qubits. Phys Rev Lett 2019; 123:210501. [PMID: 31809160 DOI: 10.1103/physrevlett.123.210501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Indexed: 06/10/2023]
Abstract
We demonstrate diabatic two-qubit gates with Pauli error rates down to 4.3(2)×10^{-3} in as fast as 18 ns using frequency-tunable superconducting qubits. This is achieved by synchronizing the entangling parameters with minima in the leakage channel. The synchronization shows a landscape in gate parameter space that agrees with model predictions and facilitates robust tune-up. We test both iswap-like and cphase gates with cross-entropy benchmarking. The presented approach can be extended to multibody operations as well.
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Affiliation(s)
- R Barends
- Google, Santa Barbara, California 93117, USA
| | | | | | - Yu Chen
- Google, Santa Barbara, California 93117, USA
| | - D Kafri
- Google, Venice, California 90291, USA
| | | | - R Collins
- Google, Santa Barbara, California 93117, USA
| | - O Naaman
- Google, Santa Barbara, California 93117, USA
| | - S Boixo
- Google, Venice, California 90291, USA
| | - F Arute
- Google, Santa Barbara, California 93117, USA
| | - K Arya
- Google, Santa Barbara, California 93117, USA
| | - D Buell
- Google, Santa Barbara, California 93117, USA
| | - B Burkett
- Google, Santa Barbara, California 93117, USA
| | - Z Chen
- Google, Santa Barbara, California 93117, USA
| | - B Chiaro
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - A Dunsworth
- Google, Santa Barbara, California 93117, USA
| | - B Foxen
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - A Fowler
- Google, Santa Barbara, California 93117, USA
| | - C Gidney
- Google, Santa Barbara, California 93117, USA
| | - M Giustina
- Google, Santa Barbara, California 93117, USA
| | - R Graff
- Google, Santa Barbara, California 93117, USA
| | - T Huang
- Google, Santa Barbara, California 93117, USA
| | - E Jeffrey
- Google, Santa Barbara, California 93117, USA
| | - J Kelly
- Google, Santa Barbara, California 93117, USA
| | - P V Klimov
- Google, Santa Barbara, California 93117, USA
| | - F Kostritsa
- Google, Santa Barbara, California 93117, USA
| | - D Landhuis
- Google, Santa Barbara, California 93117, USA
| | - E Lucero
- Google, Santa Barbara, California 93117, USA
| | - M McEwen
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - A Megrant
- Google, Santa Barbara, California 93117, USA
| | - X Mi
- Google, Santa Barbara, California 93117, USA
| | - J Mutus
- Google, Santa Barbara, California 93117, USA
| | - M Neeley
- Google, Santa Barbara, California 93117, USA
| | - C Neill
- Google, Santa Barbara, California 93117, USA
| | - E Ostby
- Google, Venice, California 90291, USA
| | - P Roushan
- Google, Santa Barbara, California 93117, USA
| | - D Sank
- Google, Santa Barbara, California 93117, USA
| | | | | | - T White
- Google, Santa Barbara, California 93117, USA
| | - J Yao
- Google, Santa Barbara, California 93117, USA
| | - P Yeh
- Google, Santa Barbara, California 93117, USA
| | - A Zalcman
- Google, Santa Barbara, California 93117, USA
| | - H Neven
- Google, Venice, California 90291, USA
| | | | - John M Martinis
- Google, Santa Barbara, California 93117, USA
- Department of Physics, University of California, Santa Barbara, California 93106, USA
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Mohseni P, Solberg JK, Karlsen M, Akselsen OM, Ostby E. Application of combined EBSD and 3D-SEM technique on crystallographic facet analysis of steel at low temperature. J Microsc 2013; 251:45-56. [PMID: 23692572 DOI: 10.1111/jmi.12041] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 03/14/2013] [Indexed: 11/27/2022]
Abstract
Electron backscatter diffraction has been increasingly used to identify the crystallographic planes and orientation of cleavage facets with respect to the rolling direction in fracture surfaces. The crystallographic indices of cleavage planes can be determined either directly from the fracture surface or indirectly from metallographic sections perpendicular to the plane of the fracture surface. A combination of electron backscatter diffraction and 3D scanning electron microscopy imaging technique has been modified to determine crystallographic facet orientations. The main purpose of this work has been to identify the macroscopic crystallographic orientations of cleavage facets in the fracture surfaces of weld heat affected zones in a well-known steel fractured at low temperatures. The material used for the work was an American Petroleum Institute (API) X80 grade steel developed for applications at low temperatures, and typical heat affected zone microstructures were obtained by carrying out weld thermal simulation. The fracture toughness was measured at different temperatures (0°C, -30°C, -60°C and -90°C) by using Crack Tip Opening Displacement testing. Fracture surfaces and changes in microstructure were analyzed by scanning electron microscopy and light microscopy. Crystallographic orientations were identified by electron backscatter diffraction, indirectly from a polished section perpendicular to the major fracture surface of the samples. Computer assisted 3D imaging was used to measure the angles between the cleavage facets and the adjacent polished surface, and then these angles were combined with electron backscatter diffraction measurements to determine the macroscopic crystallographic planes of the facets. The crystallographic indices of the macroscopic cleavage facet planes were identified to be {100}, {110}, {211} and {310} at all temperatures.
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Affiliation(s)
- P Mohseni
- Department of Material Science and Engineering, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
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Melien O, Thoresen GH, Sandnes D, Ostby E, Christoffersen T. Activation of p42/p44 mitogen-activated protein kinase by angiotensin II, vasopressin, norepinephrine, and prostaglandin F2alpha in hepatocytes is sustained, and like the effect of epidermal growth factor, mediated through pertussis toxin-sensitive mechanisms. J Cell Physiol 1998; 175:348-58. [PMID: 9572480 DOI: 10.1002/(sici)1097-4652(199806)175:3<348::aid-jcp13>3.0.co;2-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Several agents that act through G-protein-coupled receptors and also stimulate phosphoinositide-specific phospholipase C (PI-PLC), including angiotensin II, vasopressin, norepinephrine, and prostaglandin (PG) F2alpha, activated the ERK1 (p44mapk) and ERK2 (p42mapk) members of the mitogen-activated protein (MAP) kinase family in primary cultures of rat hepatocytes, measured as phosphorylation of myelin basic protein (MBP) by a partially purified enzyme, immunoblotting, and in-gel assays. All these agonists induced a peak activation (two to threefold increase in MBP-phosphorylation) at 3-5 min, followed by a brief decrease, and then a sustained elevation or a second increase of the MAP kinase activity that lasted for several hours. Although all the above agents also stimulated PI-PLC, implicating a Gq-dependent pathway, the elevations of the concentration of inositol (1,4,5)-trisphosphate did not correlate well with the MAP kinase activity. Furthermore, pretreatment of the cells with pertussis toxin markedly reduced the MAP kinase activation by angiotensin II, vasopressin, norepinephrine, or PGF2alpha. In addition, hepatocytes pretreated with pertussis toxin showed a diminished MAP kinase response to epidermal growth factor (EGF). The results indicate that agonists acting via G-protein-coupled receptors have the ability to induce sustained activation of MAP kinase in hepatocytes, and suggest that Gi-dependent mechanisms are required for full activation of the MAP kinase signal transduction pathway by G-protein-coupled receptors as well as the EGF receptor.
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Affiliation(s)
- O Melien
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Blindern, Norway
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Christoffersen T, Refsnes M, Brønstad GO, Ostby E, Huse J, Haffner F, Sand TE, Hunt NH, Sonne O. Changes in hormone responsiveness and cyclic AMP metabolism in rat hepatocytes during primary culture and effects of supplementing the medium with insulin and dexamethasone. Eur J Biochem 1984; 138:217-26. [PMID: 6321168 DOI: 10.1111/j.1432-1033.1984.tb07904.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Primary monolayer cultures of rat hepatocytes were used for studies of long-term and acute effects of hormones on the cyclic AMP system. When hepatocyte lysates were assayed at various times after plating of the cells three major changes in the metabolism of cyclic AMP and its regulation were observed: Glucagon-sensitive adenylate cyclase activity gradually declined in culture. In contrast, catecholamine-sensitive activity, being very low in normal adult male rat liver and freshly isolated hepatocytes, showed a strong and rapid increase after seeding of the cells. Concomitantly, there was an early elevation (peak approximately equal to 6 h) and a subsequent decrease in activity of both high-Km and low-Km cyclic AMP phosphodiesterase. These enzymic changes probably explained the finding that in intact cultured cells the cyclic AMP response to glucagon was diminished for 2-24 h after seeding, followed by an increase in the responsiveness to glucagon as well as to adrenergic agents up to 48 h of culture. Supplementation of the culture media with dexamethasone and/or insulin influenced the formation and breakdown of cyclic AMP in the hepatocytes. Insulin added at the time of plating moderately increased the adenylate cyclase activity assayed at 48 h, while dexamethasone had no significant effect. In the presence of dexamethasone, insulin exerted a stronger, and dose-dependent (1 pM - 1 microM), elevation of the adenylate cyclase activity in the lysates, particularly of the glucagon responsiveness. Thus, insulin plus dexamethasone counteracted the loss of glucagon-sensitive adenylate cyclase activity occurring in vitro. Kinetic plots of the cyclic AMP phosphodiesterase activity showed three affinity regions for the substrate. Of these, the two with high and intermediate substrate affinity (Km approximately equal to 1 and approximately equal to 10 microM) were decreased in the dexamethasone-treated cells. Insulin partly prevented this effect of dexamethasone. Accumulation of cyclic AMP in intact cells in response to glucagon or beta-adrenergic agents was strongly increased in cultures pretreated with dexamethasone. The results suggest that insulin and glucocorticoids modulate the effects of glucagon and epinephrine on hepatocytes by exerting long-term influences on the cyclic AMP system.
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