harnessing the power of tiny magnetic field by highly sensitiv1

8/14/2019 Harnessing the Power of Tiny Magnetic Field by Highly Sensitiv1

1/16

Harnessi ng the

power of tiny

magnetic field by

highly

sensitive

AUTHOR: POWNARTHI& T.KARTHI ..,

ELCTRONICS & COMMUNICATION ENGINEERING 3RD YEAR

Dr.MAHALINGAM COLLEGE OF ENGINERING &TECHNOLOGY

POLLACHI-TAMIL NADU

Email: [email protected],

Contact Number: +919976771910, .,

SUBMITTED TO:-
mailto:[email protected]:[email protected]


2/16

ABSTRACT:

In this paper we are going to discuss how the highly sensitive

sensors SQUID(Superconducting Quantum Interference Device) is used to

harness ie.. To control and use the power of magnetic fields. SQUID is one

of the well known technically wide-spread application of superconductors

among its other application like MAGLEVS . Further in this paper we

discuss about the use of SQUID as WAVE-DETECTOR, how it is used in

the technology of MAGNETIC RESONANCE IMAGING , which is even

developed as MICROTESLA MRI the recent development in medical field.

Squids application can be found in fields of

MAGNETOENCEPHELOGRAPHY (related to brain),

MAGNETOGASTROGRAPHY (related to stomach). NANOSQUIDS are

the recently enhanced development in the field of nano-technology, its

configuration using carbon nano tubes is presented in this paper.


3/16

Highly efficient ore separating machines are built using

super-conducting magnets.

super-conductor solenoids are used in nuclear magnetic

resonance imaging which is used in whole body scan

equipments.

super-conductors are used in new generation power saving

generators.

Through super-conductors power can be transformed without

loss thus they are used transmission lines.

MAGLEVS:

Ever since the discovery of superconductors, there has been great interest in

their use in electronics. It turns out that the magnetic properties of

superconductors has been more useful in a larger variety of applications than

the lack of resistance.

Maglev trains use superconductors to levitate the train abovemagnetic rails. This enables them to operate without friction, and therefore

acheive unheard of speeds. The maglev train below is being installed at the

Old Dominion University in Hampton, Virginia. It is the first to be installed

in the US.

Uses of Superconductors and the SC Industry


4/16

Unfortunately, due to the short track it is on, it can only reach speeds of 40

miles per hour. Maglevs, with sufficient track, can reach speeds over 300mph. A new Maglev train in Shanghai recently broke the 500 Km/h barrier

(310 mph). These trains are also more efficient because there less energy loss

to friction between the train and the track.

SUPERCONDUCTING QUANTUM INTERFERENCE DEVICES are

highly sensitive magnetometers which are used to measure very weakmagnetic signals using Josephsons effect have noise levels as low as 3

fTHz. For comparison, a typical refrigerator magnet produces 0.01 tesla

(102 T), and some processes in animals produce very small magnetic fields

between 109 T to 106 T. Recently invented atomic magnetometers are more

sensitive, but for decades SQUID sensors were the only way to measure very

small magnetic fields.

SQUID:
http://en.wikipedia.org/wiki/Tesla_(unit)http://en.wikipedia.org/wiki/Animalhttp://en.wikipedia.org/wiki/Tesla_(unit)http://en.wikipedia.org/wiki/Animal


5/16

A Superconducting Quantum Interference Device (SQUID) uses the

properties of electron-pair wave coherence and Josephson Junctions to detect

very small magnetic fields. The central element of a SQUID is a ring of

superconducting material with one or more weak links. An example is

shown in Figure with weak-links at points W and X whose critical .current,

, is much less than the critical current of the main ring. This produces a

very low current density making the momentum of the electron-pairs small.

The wavelength of the electron-pairs is thus very long leading to little

difference in phase between any parts of the ring.

Josephson effect:

The Josephson effect is the phenomenon of current flowacross two weakly coupled superconductors, separated by a very thin

insulating barrier. This arrangementtwo superconductors linked by a non-

conducting barrieris known as a Josephson junction; the current that

crosses the barrier is the Josephson current. The terms are named

eponymously after British physicist Brian David Josephson, who predicted

the existence of the effect in 1962. It has important applications in quantum-

mechanical circuits, such as SQUIDs.

The effect:

The basic equations [2] governing the dynamics of the Josephson effect are

(superconducting phase evolution equation)

(Josephson or weak-link current-phase relation)

where and are the voltage and current across the Josephson

junction, is the "phase difference" across the junction (i.e., the difference

in phase factor, or equivalently, argument, between the Ginzburg-Landaucomplex order parameter of the two superconductors comprising the

junction), and is a constant, the critical current of the junction. The critical

current is an important phenomenological parameter of the device that can

be affected by temperature as well as by an applied magnetic field. The

PRINCIPLE
http://en.wikipedia.org/wiki/Superconductorshttp://en.wikipedia.org/wiki/Eponymhttp://en.wikipedia.org/wiki/Brian_David_Josephsonhttp://en.wikipedia.org/wiki/1962http://en.wikipedia.org/wiki/Quantum_circuithttp://en.wikipedia.org/wiki/Quantum_circuithttp://en.wikipedia.org/wiki/SQUIDhttp://en.wikipedia.org/wiki/Josephson_effect#_note-barone#_note-baronehttp://en.wikipedia.org/wiki/Phase_factorhttp://en.wikipedia.org/wiki/Complex_argumenthttp://en.wikipedia.org/wiki/Ginzburg-Landau_theoryhttp://en.wikipedia.org/wiki/Ginzburg-Landau_theoryhttp://en.wikipedia.org/wiki/Superconductorshttp://en.wikipedia.org/wiki/Eponymhttp://en.wikipedia.org/wiki/Brian_David_Josephsonhttp://en.wikipedia.org/wiki/1962http://en.wikipedia.org/wiki/Quantum_circuithttp://en.wikipedia.org/wiki/Quantum_circuithttp://en.wikipedia.org/wiki/SQUIDhttp://en.wikipedia.org/wiki/Josephson_effect#_note-barone#_note-baronehttp://en.wikipedia.org/wiki/Phase_factorhttp://en.wikipedia.org/wiki/Complex_argumenthttp://en.wikipedia.org/wiki/Ginzburg-Landau_theoryhttp://en.wikipedia.org/wiki/Ginzburg-Landau_theory


6/16

physical constant, is themagnetic flux quantum, the inverse of which is

the Josephson constant.

The three main effects predicted by Josephson follow from these relations:

1.The DC Josephson effect.

2.The AC Josephson effect.

3.The inverse AC Josephson effect

The Josephson effect has found wide usage, for example in the following

areas:

1.SQUIDs, or superconducting quantum interface devices, are very sensitive

magnetometers that operate via the Josephson effect. They are widely used

in science and engineering.

2.In precision metrology, the Josephson effect provides an exactly

reproducible conversion between frequency and voltage. Since the second is

already defined precisely and practically by the caesium standard, the

Josephson effect is used, for most practical purposes, too.

3.Single-electron transistors are often constructed of superconductingmaterials, allowing use to be made of the Josephson effect to achieve novel

effects. The resulting device is called a "superconducting single-electron

transistor"[3].

The DC SQUID was invented in 1964 by Robert Jaklevic, John Lambe, Arnold Silver,

and James Mercereau of Ford Research Labs after B. D. Josephson postulated the

Josephson effect in 1962and the first Josephson Junction was made by John Rowell

and Philip Anderson at Bell Labs in 1963. The RF SQUID was invented in 1965 by

James Edward Zimmerman and Arnold Silver at Ford.

History and design:
http://en.wikipedia.org/wiki/Magnetic_flux_quantumhttp://en.wikipedia.org/wiki/Josephson_constanthttp://en.wikipedia.org/wiki/SQUIDhttp://en.wikipedia.org/wiki/Magnetometerhttp://en.wikipedia.org/wiki/Metrologyhttp://en.wikipedia.org/wiki/Frequencyhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Secondhttp://en.wikipedia.org/wiki/Caesium_standardhttp://en.wikipedia.org/wiki/Single-electron_transistorhttp://en.wikipedia.org/wiki/Superconductinghttp://en.wikipedia.org/wiki/Josephson_effect#_note-0#_note-0http://en.wikipedia.org/wiki/1964http://en.wikipedia.org/wiki/B._D._Josephsonhttp://en.wikipedia.org/wiki/Josephson_effecthttp://en.wikipedia.org/wiki/1962http://en.wikipedia.org/wiki/1962http://en.wikipedia.org/wiki/Bell_Labshttp://en.wikipedia.org/wiki/Bell_Labshttp://en.wikipedia.org/wiki/1963http://en.wikipedia.org/wiki/1963http://en.wikipedia.org/wiki/James_Edward_Zimmermanhttp://en.wikipedia.org/wiki/Magnetic_flux_quantumhttp://en.wikipedia.org/wiki/Josephson_constanthttp://en.wikipedia.org/wiki/SQUIDhttp://en.wikipedia.org/wiki/Magnetometerhttp://en.wikipedia.org/wiki/Metrologyhttp://en.wikipedia.org/wiki/Frequencyhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Secondhttp://en.wikipedia.org/wiki/Caesium_standardhttp://en.wikipedia.org/wiki/Single-electron_transistorhttp://en.wikipedia.org/wiki/Superconductinghttp://en.wikipedia.org/wiki/Josephson_effect#_note-0#_note-0http://en.wikipedia.org/wiki/1964http://en.wikipedia.org/wiki/B._D._Josephsonhttp://en.wikipedia.org/wiki/Josephson_effecthttp://en.wikipedia.org/wiki/1962http://en.wikipedia.org/wiki/Bell_Labshttp://en.wikipedia.org/wiki/1963http://en.wikipedia.org/wiki/James_Edward_Zimmerman


7/16

There are two main types of SQUID: DC and RF. RF SQUIDs can work

with only one Josephson junction, which might make them cheaper to

produce, but are less sensitive.

The traditional superconducting materials for SQUIDs are pure niobium or

a lead alloy with 10% gold or indium, as pure lead is unstable when its

temperature is repeatedly changed. To maintain superconductivity, the entire

device needs to operate within a few degrees of absolute zero, cooled with

liquid helium.

"High temperature" SQUID sensors are more recent; they are made ofhigh

temperature superconductors, particularly YBCO, and are cooled by liquid

nitrogen which is cheaper and more easily handled than liquid helium. They

are less sensitive than conventional "low temperature" SQUIDs but good

enough for many applications.

WORKING:

If a magnetic field, , is applied perpendicular to the plane of the ring, a

phase difference is produced in the electron-pair wave along the path XYW

and WZX. A small current, , is also induced to flow around the ring,

producing a phase difference across the weak links. Normally the inducedcurrent would be of sufficient magnitude to cancel the flux in the hole of the

ring but the critical current of the weak-links prevents this.
http://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Radio_frequencyhttp://en.wikipedia.org/wiki/Josephson_junctionhttp://en.wikipedia.org/wiki/Superconductinghttp://en.wikipedia.org/wiki/Niobiumhttp://en.wikipedia.org/wiki/Leadhttp://en.wikipedia.org/wiki/Alloyhttp://en.wikipedia.org/wiki/Goldhttp://en.wikipedia.org/wiki/Indiumhttp://en.wikipedia.org/wiki/Absolute_zerohttp://en.wikipedia.org/wiki/Liquid_heliumhttp://en.wikipedia.org/wiki/High-temperature_superconductivityhttp://en.wikipedia.org/wiki/High-temperature_superconductivityhttp://en.wikipedia.org/w/index.php?title=Yttrium_barium_copper_oxide_(YBCO)&action=edithttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Radio_frequencyhttp://en.wikipedia.org/wiki/Josephson_junctionhttp://en.wikipedia.org/wiki/Superconductinghttp://en.wikipedia.org/wiki/Niobiumhttp://en.wikipedia.org/wiki/Leadhttp://en.wikipedia.org/wiki/Alloyhttp://en.wikipedia.org/wiki/Goldhttp://en.wikipedia.org/wiki/Indiumhttp://en.wikipedia.org/wiki/Absolute_zerohttp://en.wikipedia.org/wiki/Liquid_heliumhttp://en.wikipedia.org/wiki/High-temperature_superconductivityhttp://en.wikipedia.org/wiki/High-temperature_superconductivityhttp://en.wikipedia.org/w/index.php?title=Yttrium_barium_copper_oxide_(YBCO)&action=edit


8/16

The quantum condition that the phase change around the closed path must

equal can still be met by large phase differences across the weak-links

produced by even a small current. An applied magnetic field produces a

phase change around a ring, as shown in Equation which in this case is

equal to

where is the flux produced in the ring by the applied magnetic field

may not necessarily equal an integral number of fluxons so to ensure the

total phase change is a multiple of a small current flows around the ring,

producing a phase difference of across the two weak-links, giving a

total phase change of

The phase difference due to the circulating current can either add to or

subtract from that produced by the applied magnetic field but it is more

energetically favourable to subtract: in this case a small anti-clockwise

current,

Substituting values from Equations , the magnitude of the circulating

current, , can be obtained

As the flux in the ring is increased from 0 to the magnitude of increases to a

maximum. As the flux is increased greater than it is now energetically favourable

for a current, , to flow in a clockwise direction, decreasing in magnitude to 0 as the

SQUID AS MAGNETOMETER:


9/16

flux reaches . The circulating current has a periodic dependence on the magnitude of

the applied field, with a period of variation of , a very small amount of magnetic flux.Detecting this circulating current enables the use of a SQUID as a magnetometer.

We report on the noise characterization of a two-stage dc

superconducting quantum interference device ~SQUID! amplifier developed

for resonant gravitational wave detectors. The back action noise is estimated

by coupling the SQUID to an electrical resonator at 1.6 kHz with

Q51.13106. From measurements of back actionand additive SQUID noise,

performed in the temperature range 1.54.2 K, an upper limit is set on the

noise temperature Tn of the device at the resonator frequency. The best valueobtained at 1.5 K is Tn


10/16

enhanced7 or much bigger than expected8 and on a commercial system. they

report the noise measurement on a twostage.

SQUID system developed for the GW detector:

AURIGA,5 which achieves the best measured noise

temperature of an amplifier operating in the audio-frequency range,more

than one order of magnitude lower than previous results .The measurement

method is very similar to that described

The SQUID is coupled to a highqualityfactor electrical rLC resonator

through a superconducting matching transformer The resonator is

vibrationally and magnetically shielded enough to make excess noise

negligible, so that only two modeled sources of

voltage noise act on the resonator: the thermal source Vth associated with

resonator intrinsic losses, with spectral density 4kbTr, and the SQUID backaction generator Vn . The input impedance of the SQUID is represented by a

pure inductance Li . A noise-free resistor rc is added to the model to take into

account the effect of the real part of the SQUID dynamic input impedance10

or the effect of additional feedback loops that can be employed to realize a

cold damping of the resonator.

The SQUIDs are placed in different shields and are

connected to the room-temperature electronics through different cables in

order to avoid any stray cross talk between the wires. The SQUID sensor,biased through a batterypowered current box, is not modulated and its output

voltage is fed through a matching resistor Rm52.2 V to the SQUID

amplifier, which is finally read out by standard manufacturer electronics

with a 500 kHz modulation scheme. The system

is operated in a conventional flux locked loop, with the output signal from

the amplifier electronics sent to a one-pole integrator and fed back to the

SQUID sensor. The maximum bandwidth of the system in closed-loop mode

is limited by various filtering stages to about 50 kHz. procedure over the

whole bandwidth, about 200 Hz around the resonance for the present

experimental setup, where the Resonator noise is dominant over the SQUIDadditive noise. Finally, we remark that the minimum measured upper limit

on the noise temperature, obtained at 1.5 K, is Tn8516 mK. It corresponds to

a minimum detectable energy of, at most, 200 quanta in a resonant GW

detector operating in the range of frequency around 1 kHz.


11/16


12/16

Microtesla MRI with a superconducting quantum

interference device

NMR signals generated by nuclear spins that precess in a staticmagnetic field B0 in the presence of magnetic field gradients. Most clinical

MRI scanners operate at a magnetic field B0 _ 1.5 T, corresponding to a

proton resonance frequency of 64 MHz. Because these systems rely on large

superconducting magnets, they are costly and demanding of infrastructure.

On the other hand, low-field imagers have the potential to be less expensive,

less confining, and more mobile. The major obstacle is the intrinsically

low sensitivity of the low-field NMR experiment. Here, we show that

prepolarization of the nuclear spins and detection with a superconducting

quantum interference device (SQUID) yield a signal that is independent ofB0, allowing acquisition of highresolution

MRIs in microtesla fields.

MRI scanners enable fast, noninvasive, and high-resolution

imaging of organs and soft tissue. The images are reconstructed from the

measurement field eliminates inhomogeneous broadening of the NMR lines,

resulting in enhanced signal-to-noise ratio and spatial resolution for a fixed

strength of the magnetic field gradients used to encode the image. We

present high-resolution images of phantoms and other samples and T1-

weighted contrast images acquired in highly inhomogeneous magnetic fields

of 132 _T; here, T1 is the spin-lattice relaxation time. These techniquescould readily be adapted to existing multichannel SQUID systems used for

magnetic source imaging of brain signals. Further potential applications

include low-cost systems for tumor screening and imaging peripheral regions

of the body.

The conventional MRI receiver coil operates on the principle

of Faraday induction (14): the signal is therefore proportional to the product

of sample magnetization and the frequency of nuclear

spin precession. In the high-temperature limit, the thermal magnetization

of the sample scales linearly with the magnetic fieldstrength. Similarly, the nuclear precession frequency is proportional

to the strength of the applied field. In the case of conventional

detection, therefore, the NMR signal strength scales as B0


13/16

A complementary approach involves reduction of the noise of the NMR

receiver (11), most notably by detecting the NMR signals with a dc

superconducting quantum interference device (SQUID) (12). The dc SQUID

consists of a superconducting loop interrupted at each of two points by a

Josephson junction. When the SQUID is biased with a current Ib slightly

above its critical current, the voltage across it is periodic in the flux applied

to the loop, with a period of the flux quantum, A state-of-the-art low-

transition temperature (low-Tc) SQUID can detect a magnetic flux change of

in a unit bandwidth. To increase its sensitivity to magnetic fields, the SQUID

is often operated with a superconducting flux transformer, which consists of

a pickup circuit (with inductance Lp) in series with an input coil (with

inductance Li) that is tightly coupled to the SQUID loop. Flux quantization

implies that a flux applied to the pickup circuit generates a frequency-

independent supercurrent in the transformer, which in turn couples flux to

the SQUID. Thus, the untuned SQUID magnetometer detectsbroadband at arbitrarily low frequencies with no loss in sensitivity. The

unsurpassed sensitivity of the SQUID has been exploited as an alternative to

conventional NMR detection since the 1989

Although the majorityof SQUID NMR studies were performed on

solid samples at liquid helium temperatures, there have been several attempts

at SQUID-detected MRI of room-temperature samples Recently, it was

demonstrated (16, 17) that NMR detection with an untuned SQUID

magnetometer in considerably lower fields (microtesla) can be used to

enhance both spectral resolution and signal-to-noise ratio (SNR). For a

sample magnetization that is fixed, for example by prepolarization, the

frequency- independent response of the untuned SQUID implies that the

integrated intensity of the NMR lines is independent of B0. If the NMR

linewidth is limited by magnetic field inhomogeneity, reduction of B0

narrows the NMR lines, thereby improving spectral resolution. Because the

detector is untuned, the amplitude of the NMR peak grows, leading to

improved SNR. Here we extend these ideas to MRI, where the reduction in

B0 enhances both SNR and spatial resolution for a fixed strength of the

magnetic field gradients used to encode the image SQUID Receiver. The

low-Tc dc SQUID was based on niobium thin films and niobiumaluminumoxideniobium tunnel barriers. The input circuit consisted of a niobium-wire

pickup coil wound as a 1 _ 2 _ 1-turn, second-order axial gradiometer, with

150-mm baseline and 65-mm loop diameters, connected to a multiturn thin

film niobium input coil integrated onto the SQUID chip.


14/16

Environmental Noise Reduction

Because of the exquisite intrinsic sensitivity of the SQUID, we took

considerable care to ensure that the detector was not overwhelmed by

external sources of magnetic field noise and interference. Except at 60 Hzand its harmonics, the magnetic field noise in our laboratory was of the order

of 10 pT_Hz_1/2 at low frequencies (tens of Hz), decreasing to _1

pT_Hz_1/2 at a few kHz. Gradiometric configuration of the receiver coil

reduces sensitivity to distant sources of noise and interference while

maintaining high sensitivity to nearby signal

sources. Our as-made second-order hardware gradiometer typically

achieved a balance of better than 1:100 against uniform fields applied either

in plane or out of plane. To reduce the environmental noise contribution

further, we chose a measurement field to obtain an imaging band in a clean

region of the environmental magnetic field spectrum; the broadbandsensitivity of the untuned SQUID magnetometer offered consider-

Results

High-Resolution Imaging of MRI Phantoms

T1-Contrast Imaging.

High-Resolution and Slice-Selected MRI of Peppers

OTHER Uses for SQUIDs

Magnetogastroography (MEG),

The extreme sensitivity of SQUIDs makes them ideal for studies in biology.

Magnetoencephalography (MEG), for example, uses measurements from an

array of SQUIDs to make inferences about neural activity inside brains.

Because SQUIDs can operate at acquisition rates much higher than the

highest temporal frequency of interest in the signals emitted by the brain

(kHz), MEG achieves good temporal resolution. Another area where

SQUIDs are used is magnetogastrography, which is concerned with

recording the weak magnetic fields of the stomach.

Probably the most common use of SQUIDs is in magnetic property

measurement systems. These are turn-key systems, made by several

manufacturers, that measure the magnetic properties of a material sample.

This is typically done over a temperature range from that of liquid helium

(~4K), to a couple of hundred degrees above room temperature.
http://en.wikipedia.org/wiki/Magnetoencephalographyhttp://en.wikipedia.org/wiki/Magnetoencephalographyhttp://en.wikipedia.org/wiki/Neuronhttp://en.wikipedia.org/wiki/Brainhttp://en.wikipedia.org/w/index.php?title=Magnetogastrography&action=edithttp://en.wikipedia.org/wiki/Magnetoencephalographyhttp://en.wikipedia.org/wiki/Magnetoencephalographyhttp://en.wikipedia.org/wiki/Neuronhttp://en.wikipedia.org/wiki/Brainhttp://en.wikipedia.org/w/index.php?title=Magnetogastrography&action=edit


15/16

For example, UC Berkeley Physics Professor John Clarke has been using

SQUID's as a detector to perform Magnetic Resonance Imaging. While high

field MRI uses precession fields of one to several tesla, SQUID-detected

MRI uses measurement fields that lie in the microtesla regime. Since the

NMR signal drops off as the square of the magnetic field, a SQUID is used

as the detector because of its extreme sensitivity. The SQUID coupled to a

second-order gradiometer and input circuit, along with the application of

gradients are the fundamental entities which allows his research group to

retrieve noninvasive images. SQUID-detected MRI has many advantages

such as the low cost required to build such a system, its compactness, the

ability to image human extremities, and its application for tumor screening.

Another application is the scanning SQUID microscope, which uses a

SQUID immersed in liquid helium as the probe. The use of SQUIDs in oil

prospecting, mineral exploration, earthquake prediction and geothermalenergy surveying is becoming more widespread as superconductor

technology develops; they are also used as precision movement sensors in a

variety of scientific applications, such as the detection of gravity waves.

Four SQUIDs were employed on Gravity Probe B in order to test the limits

of the theory ofgeneral relativity.

INTO THE WORLD OF NANO:

A French scientific team has developed the first superconducting quantum

interference device, known as a nanoSQUID, for measuring magnetic fields.

Researchers from Laboratoire Louis Nel have presented in a paper

a superconducting quantum interference device (SQUID) with single-walled

carbon nanotube (CNT) Josephson junctions. Quantum confinement in each

junction induces a discrete quantum dot (QD) energy level structure, which

can be controlled with two lateral electrostatic gates. In addition, a backgate

electrode can vary the transparency of the QD barriers, thus permitting to

change the hybridization of the QD states with the superconducting contacts.

The gates are also used to directly tune the quantum phase interference of theCooper pairs circulating in the SQUID ring. Optimal modulation of the

switching current with magnetic flux is achieved when both QD junctions

are in the "on" or "off"- state. In particular, the SQUID design establishes

that these CNT Josephson junctions can be used as gate-controlled pi-

junctions, that is, the sign of the current-phase relation across the CNT

junctions can be tuned with a gate voltage. The CNT SQUIDs are sensitive
http://en.wikipedia.org/wiki/UC_Berkeleyhttp://en.wikipedia.org/wiki/John_Clarkehttp://en.wikipedia.org/wiki/Magnetic_Resonance_Imaginghttp://en.wikipedia.org/w/index.php?title=Gradiometer&action=edithttp://en.wikipedia.org/w/index.php?title=Scanning_SQUID_microscope&action=edithttp://en.wikipedia.org/wiki/Heliumhttp://en.wikipedia.org/wiki/Petroleumhttp://en.wikipedia.org/wiki/Prospectinghttp://en.wikipedia.org/wiki/Mineral_explorationhttp://en.wikipedia.org/wiki/Earthquakehttp://en.wikipedia.org/wiki/Geothermal_energyhttp://en.wikipedia.org/wiki/Geothermal_energyhttp://en.wikipedia.org/wiki/Gravity_wavehttp://en.wikipedia.org/wiki/Gravity_Probe_Bhttp://en.wikipedia.org/wiki/General_relativityhttp://lab-neel.grenoble.cnrs.fr/http://en.wikipedia.org/wiki/UC_Berkeleyhttp://en.wikipedia.org/wiki/John_Clarkehttp://en.wikipedia.org/wiki/Magnetic_Resonance_Imaginghttp://en.wikipedia.org/w/index.php?title=Gradiometer&action=edithttp://en.wikipedia.org/w/index.php?title=Scanning_SQUID_microscope&action=edithttp://en.wikipedia.org/wiki/Heliumhttp://en.wikipedia.org/wiki/Petroleumhttp://en.wikipedia.org/wiki/Prospectinghttp://en.wikipedia.org/wiki/Mineral_explorationhttp://en.wikipedia.org/wiki/Earthquakehttp://en.wikipedia.org/wiki/Geothermal_energyhttp://en.wikipedia.org/wiki/Geothermal_energyhttp://en.wikipedia.org/wiki/Gravity_wavehttp://en.wikipedia.org/wiki/Gravity_Probe_Bhttp://en.wikipedia.org/wiki/General_relativityhttp://lab-neel.grenoble.cnrs.fr/


16/16

local magnetometers, which are very promising to study the magnetisation

reversal of an individual magnetic particle or molecule placed on one of the

two carbon nanotube Josephson junctions.

SQUIDs in fiction

The science fiction writerWilliam Gibson made reference to SQUIDs

in his 1981 story Johnny Mnemonic, where a genetically engineered

ex-military dolphin uses a SQUID implant to read a memory device in

the title character's brain.

In the film Strange Days, SQUIDs are used to record and play back

human memories, some of which are exchanged on theblack market. In Michael Crichton's 1999 novel Timeline, SQUIDs are mentioned as

a part of the Quantum Teleportation device developed by ITC.

Jon Courtenay Grimwood's novel redRobe makes reference to SQUID

probes being used to read memories and thoughts as part of a

particularly invasive interrogation.
http://en.wikipedia.org/wiki/Science_fictionhttp://en.wikipedia.org/wiki/William_Gibsonhttp://en.wikipedia.org/wiki/Johnny_Mnemonichttp://en.wikipedia.org/wiki/Strange_Days_(film)http://en.wikipedia.org/wiki/Black_markethttp://en.wikipedia.org/wiki/Michael_Crichtonhttp://en.wikipedia.org/wiki/Timeline_(novel)http://en.wikipedia.org/wiki/Quantum_Teleportationhttp://en.wikipedia.org/wiki/Jon_Courtenay_Grimwoodhttp://en.wikipedia.org/wiki/RedRobehttp://en.wikipedia.org/wiki/Science_fictionhttp://en.wikipedia.org/wiki/William_Gibsonhttp://en.wikipedia.org/wiki/Johnny_Mnemonichttp://en.wikipedia.org/wiki/Strange_Days_(film)http://en.wikipedia.org/wiki/Black_markethttp://en.wikipedia.org/wiki/Michael_Crichtonhttp://en.wikipedia.org/wiki/Timeline_(novel)http://en.wikipedia.org/wiki/Quantum_Teleportationhttp://en.wikipedia.org/wiki/Jon_Courtenay_Grimwoodhttp://en.wikipedia.org/wiki/RedRobe

harnessing the power of tiny magnetic field by highly sensitiv1

Documents