tag:blogger.com,1999:blog-13869903.post115711568593178298..comments2024-03-29T02:45:10.096-05:00Comments on nanoscale views: ...and still MORE hype....Douglas Natelsonhttp://www.blogger.com/profile/13340091255404229559noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-13869903.post-1157917694285810072006-09-10T14:48:00.000-05:002006-09-10T14:48:00.000-05:00This is certainly nothing new. I can recall very s...This is certainly nothing new. I can recall very similar sorts of hype back in the late 90's when MEMS were the hot item: http://www.findarticles.com/p/articles/mi_m1511/is_n3_v19/ai_20324743/pg_2<BR/>In this article from 1998, they predict MEMS submarines swimming through your bloodstream. 8 years later all we really have are DLPs and MEMS air bag sensors. Sure, this hype is ridiculous. However, it seems to be a necessary evil to bring ever scarcer research dollars into an emerging engineering field when the possible applications are still uncertain (ie. think of the laser).<BR/><BR/>-----------------------------<BR/>www.plasmonicfocus.comJoshhttps://www.blogger.com/profile/05114138620543414598noreply@blogger.comtag:blogger.com,1999:blog-13869903.post-1157218754442386032006-09-02T12:39:00.000-05:002006-09-02T12:39:00.000-05:00Regarding David's question about decoherence: the...Regarding David's question about decoherence: the third lead can't just decohere, or you'd only modulate the current from the constructive interference result (2 x the classical conduction of the two paths) to the classical result. Not much of a switch. To be good as a switch, you'd want to go from constructive to destructive interference. That being said, there are real subtle points here. The calculations are at T = 0 if I recall correctly, and truly worrying about decoherence means keeping track of all the various inelastic processes that can happen. Generally, for the isolated molecule I'd say this isn't a problem. It has a very discrete spectrum with large energy gaps, so inelastic processes that change the electronic state should be very suppressed. However, once the molecule is hybridized with the electronic states of the leads, things get much more complicated. At room temperature in a diffusive normal metal, the coherence length is something like 1 nm, which is comparable to the size of the molecule. Could be an issue. The biggest problem, though, would just be making the structure.Douglas Natelsonhttps://www.blogger.com/profile/13340091255404229559noreply@blogger.comtag:blogger.com,1999:blog-13869903.post-1157192351089919342006-09-02T05:19:00.000-05:002006-09-02T05:19:00.000-05:00Peter,I echo the sentiment from my microelectronic...Peter,<BR/><BR/>I echo the sentiment from my microelectronics experience. Though I learned the hard way that it was used as a practical predictor from stuff like scaling laws to the type and amount of chemicals the next fab generation would consume.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13869903.post-1157141405308623742006-09-01T15:10:00.000-05:002006-09-01T15:10:00.000-05:00>Any scientist who mentions the >movie "Fantastic ...>Any scientist who mentions the >movie "Fantastic Voyage" when >talking on the record (e.g., to a >reporter) ought to be taken out >into the courtyard and shot.<BR/><BR/>And Moore's law! I am so sick of nanotalks with Moore's law! I exagerate some, because in some audiences it makes sense to intro with this, but much of the time it is just such a cliche.<BR/><BR/>While I was at UCLA their CNSI nanoinstitute started these weekly colloquia with high-profile speakers. For the 1st year every one of them started off with Moore's law in the first few slides. Once in a while would be OK, but we got hit with it everyweek and if it wasn't already a tired worn out narrative at the beginning of the year, it certainly was by the end. It got to be a cross-departmental joke. Everything could be related to Moore's law!<BR/><BR/>>"University of Arizona physicist >Charles A. Stafford said. "Using >electricity to raise and lower >energy barriers has worked for a >century of switches, but that >approach is about to hit the wall."Peter Armitagehttps://www.blogger.com/profile/11567089164372083820noreply@blogger.comtag:blogger.com,1999:blog-13869903.post-1157132792781126852006-09-01T12:46:00.000-05:002006-09-01T12:46:00.000-05:00Hype bad! Back to the physics!As I understand the...Hype bad! Back to the physics!<BR/><BR/>As I understand the paper, the proposed device works by using destructive interference for the two paths around the benzene for the "no current transmision" state and then applies a third lead to cause decoherence and case the "current transmision" state. Why should we believe that this destructive interference effect isn't destroyed by other decoherence mechanisms?<BR/><BR/>I guess a related question is what fidelities are people achieving and striving for with molecular transistors? Is it okay to have a molecular transistor which fails once every thousand switching events? And then do people imagine using such transistors redundantly to get this failure rate down?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13869903.post-1157127217541689802006-09-01T11:13:00.000-05:002006-09-01T11:13:00.000-05:00Any scientist who mentions the movie "Fantastic Vo...Any scientist who mentions the movie "Fantastic Voyage" when talking on the record (e.g., to a reporter) ought to be taken out into the courtyard and shot.<BR/><BR/>Ok, maybe that's a bit harsh. But you get the idea.Anonymousnoreply@blogger.com