Talk:SQUID

SQUID MEAT

Mmmmm, tastes like cold.

I had a look through the article again and noticed one of the more everyday uses doesn't appear to be mentioned. They are used by some abattoirs to check meat for metallic objects prior to packing; e.g. syringe blades, hooks or other bits of stuff associated with rearing and processing meat. The element is inside a box that sits over the conveyor and the meat zooms through. This is obviously a nice method of doing it as it doesn't require any radiation sauce, which is spicy and burns. —Preceding unsigned comment added by 86.180.250.26 (talk) 13:56, 5 April 2011 (UTC)

Citing the person instead of the research

Mention to UC Berkeley professor Clarke, in the "Uses for SQUIDs" section is inappropriate. Surely the writer was well-intentioned in writing it. But by citing his name and affiliation, we emphasize the person and not the significance of the work we want to cite. Furthermore, there are many researchers across the world involved with SQUIDs. If we cite one, why should someone else not come around and cite another researcher? Soon we'd have a section on researchers, advertizing their work. Wikipedia is not an advertizement service. I suggest the reference to the person (Dr. Clarke) be removed. It is the work which is significant, and such work is never the product of one single individual. As such, I have edited the original sentence. This paragraph cites my reasoning. —Preceding unsigned comment added by 75.12.148.191 (talk) 01:47, 12 May 2008 (UTC)

Units?

Is this correct? 3 fT·Hz−½? That reads as "3 femto-tesla per (square root of hertz)", which in turn expands to "3 femto-tesla per (square root of (1/seconds))". Seems like a really odd unit to me. --Carnildo 05:34, 5 August 2005 (UTC)

Yes, it is correct. Just as electrical voltage noise is specified in units of volts per root Herts (V·Hz−½), magnetic field noise is specified in units of Tesla per root Herts (T·Hz−½).

For example, the root-mean-squared thermal voltage noise in a bandwidth of $\Delta f$, from a resistor of value R at temperature T is

$V_{n}={\sqrt {4k_{B}TR\Delta f}}$

In order to specify the voltage noise, whether thermal or otherwise, in a measurement-bandwidth-independent-manner, you really specify $V_{n}/{\sqrt {\Delta f}}$ rather than $V_{n}$, hence the units for voltage noise having units of volts per root Herts (V·Hz−½). An analogous calculation of magnetic noise handles the bandwidth issue the same way, hence resulting in units for magnetic noise of Tesla per root Herts (T·Hz−½). To figure out what the actual magnetic noise observed will be from a SQUID with a noise floor of 3 fT·Hz−½, one has to take the square root of the bandwidth one will be measuring over, and multiply that by 3 fT·Hz−½. This 3 fT·Hz−½ number ignores the fact that at low enough frequency (<1 Hz in a good SQUID), 1/f noise will take over.

-- Former SQUID Guy 01:06, 8 August 2005 (UTC)

High Temperature SQUIDS

Regarding the added info on HT SQUIDS, one of many references would be this [1]

03:29, 4 June 2006 (UTC)~ Changed 'microbiology' to 'biology' under the uses section. I've never heard of squids being used in microbiology. Even if they are, this is not explained in the remainder of the article.

Expanding the Article

Does anyone fancy expanding this article a bit. (At least to give a mention to Clarke, Drung, Ketchen etc.) - I will give it a go if no-one else wants to - if I have enough time/energy! 195.93.21.6 22:12, 22 July 2006 (UTC)

Take alook at User:Slicky/Microscopy in science, which has a subsection relating to Scanning Magnetic Flux Microscope. DFH (talk) 07:51, 11 April 2008 (UTC)

SQUID based microscopes

A leading company in the field of Scanning SQUID Microscopes is Neocera, Inc. [2]. DFH (talk) 08:13, 11 April 2008 (UTC)

Citations

The only citation on this page is broken. Unless the original author can remember where he got what information, it's going to need a complete rewrite with proper inline citations and a reference list. --Dbutler1986 (talk) 07:04, 3 June 2008 (UTC)

A quick check on the hosting web site of the original citation turned up a PDF version of the same material (verified this at the Internet Archive, http://archive.org). Agree that all the other statements in the article desperately need reliable citations. Tjarrett (talk) 17:55, 6 June 2008 (UTC)

Missing Figure?

A figure is referred to in the DC SQUID section - where is it? --216.18.1.210 (talk) —Preceding undated comment added 20:22, 13 May 2009 (UTC).

I AGREE!!!!!

It reads as if the section describing the squid V(phi) function was just lifted from a book. Someone should write a section explaining the maths analogy of the of the SQUID with the optical interference of light. It would also explain why the SQUID is an INTERFERENCE device, something that is not made clear in the article

But what do I know? 217.42.143.111 (talk) 19:47, 3 September 2009 (UTC)

I'm not sure how to do references of papers, but here is the where the noise level of 3 fT.Hz^(-1/2) is cited. [3] So if someone else wants to put that in, its listed at the end of the abstract 134.219.128.157 (talk) 12:04, 19 February 2010 (UTC)

Added. Thank you. Materialscientist (talk) 12:45, 19 February 2010 (UTC)

SQUIDs as generators

The article currently characterizes SQUIDs as sensitive detectors of electromagnetism. However, many technologies that detect can also generate. SQUIDs can generate intense, highly focused magnetic fields. The main modification needed is the avoidance of the temperature rise due to the relatively high power (heat is an enemy of superconductivity).

Since magnetic fields are unaffected by biological tissues, a SQUID creating a varying magnetic field will generate an electric current inside tissue.

Three or more SQUIDs can generate a focused electric current at any desired position inside tissue.

An application for this effect is Deep brain stimulation, where a series of electric pulses generated at a specific location in the brain manages various diseases, such as Parkinson's disease and treatment-resistant Depression. David Spector 21:39, 10 March 2010 (UTC)

Interesting - but why would you want to use squids for this when you could just generate the fields using normal induction coils? Is it because the fields requred are relatively large? (and if they are then why use squids when you can use just normal superconducting coils?) 81.153.45.40 (talk) 19:22, 20 May 2010 (UTC)

The same questions work in reverse, why use SQUIDS for MEG if coils alone will detect fields. Accuracy would be one answer. Deep brain stimulation is currently WAY behind the sensors. Which is a shame, as it could revolutionise neuroscience and our way of thinking if pinpoint, controllable stimulation could be fed back to the brain without chopping holes in the skull and jabbing pins in at roughly the right place. I would argue that once this become feasible, it will be more important to humanity than when we started making tools; we would not only have done something other animals can not do, we would no longer exist as animals or be subject to natural selection. —Preceding unsigned comment added by 86.180.250.26 (talk) 14:06, 5 April 2011 (UTC)

SQUID, Qubits and quantum computing

The article says that Rf-SQUIDs can be used to prepare qubits, however, they have been implemented by D-Wave in the first commercial quantum computer. I would change that part of the article and update the links. — Preceding unsigned comment added by 161.111.235.10 (talk) 10:07, 29 July 2011 (UTC)

How else are SQUIDs related to quantum computing? --Daviddwd (talk) 02:01, 18 September 2018 (UTC)

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Assessment comment

The comment(s) below were originally left at Talk:SQUID/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

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I`ve tried to contact Brian Josephson many times: There is no such thing as weak forces only a deception put in place around 1930 after tesla died by the military and industires that built that technology there after. Its left huge amounts of unmeasured EMF and noise generated by so called new and Green technology. Where experts are addressing us so called electrically sensitive indervidules as weak being exposed to this low level and weak radiation. The military made it possible for unscroplus companies to sell as green and likewise electromagnetic healing systems as low level yet power effeicient. So called old technology is based on a North phase or polarity where as new tech or reverse technology is based on a South polarity as far as reading on a meter... Hence new technology does not obey the normal low powered low level radiation... (Neather can it be earthed, filtered or sheilded because of this change polarity, it creates a feed-back machisum and there`s nowhere for the power to go. But into the far field) Its no longer being read in Hertz or Tesla`s but some undisclosed very powerful measurement which is way off scale.. This is part microwave and part nulcear as its the basis of the philadeliphia Experiment and the Manhattan Project. According to true science the sine wave as its rotated over a 360 deg it becomes more powerful and its at Max. power in the non-linear or scanlar phase.. Again this was discribed as low level radiation, yet these waves are the basis of digital tV and communications and move very fast. They are now known to be biologically active. They are being used in electromagnetic healing, but are being sold as low powered and safe.. The problems is they mask out conditions, while seemingly correting them. These systems were known as non-lethal weapons back in the 1st world war... They gone on to form Tasar guns (The police have been told tasers are only low level radiation; if one really looks logically how can this be true?) and Tetra microwave communications as well as so called quantum/soild state technology. Which has broken into the total consciouness. (Read psychotronic/mind control) Even Earthquakes are mistakenly labelled as low level radiation or a weak force.. Its up to the military to tell domestic law, through NATO (The Australia Group) what a non-lethal weapon is, so it can leave mobile phones and other communications mislabelled as low powered. (Chocolate-cream 19:28, 13 April 2007 (UTC)) Chocholate-cream

Last edited at 19:28, 13 April 2007 (UTC). Substituted at 05:11, 30 April 2016 (UTC)