2. Can sense weak magnetic
fields
Threshold magnetic field
sensor ≈10-12 T
▪ Earth’s Magnetic field ≈50μT
Compact
Portable
Advanced
Communication applications!
MEG
Source: http://csis.org/blog/history-space-radar-brief-survey-radar-capabilities
Boeing Hawk Eye
1
4. Barrier between two superconducting
materials - (SIS) or (SNS)
Source: S.A Cybart. Planar Josephson Junctions and Arrays. Dissertation, University of California, San Diego, 2005.
3
5. Two parallel Josephson Junctions
Resistively Shunted Josephson (RSJ)
Magnetic flux through a SQUID is quantized
Flux Quantum: φ0=h/2e
Applied Magnetic field: φa
Source: J. Clarke, A.I. Braginski, The SQUID Handbook, Vol. 1, 2004.
4
φa=(n+1/2) φ0
φa=nφ0
φa
11. Magnet producing
a couple of mT
Positioned in front
ofYBCO chip
Important for
device
characterization
Magnet for
YBCO Chip
10
12. Compact
Efficient
Portable
Source:
http://www.supraconductivite.fr
Source: http://wall.alphacoders.com/big.php?i=309497
Source: NASA 11
Magnetoencephalography (MEG)
Space Systems
http://www.mnn.com/earth-matters/space/stories/military-nasa-look-to-partner-with-commercial-satellite-industry
13. Dr. Robert Dynes
Dr. Shane Cybart
Graduate students:TravisWong and Ethan Cho
Undergraduate students: Bjorn Wehlin and Meng Ma
UC LEADS program
STARS program
THANKYOU! 12
Direction finding
Wide band width
Want to go from meters to cm for direction finding antennas
Devices already out there that do similar functions using Low transition superconductivity
Tunneling of copper pairs through the barrier for current flow(wave function seen here)
If put in parallel you get phases occur
If wave function is out of phase then
Fundamental building block of devices that I will discuss later called Superconducting QUantum Interference Devices
External mag. Field induces a specific flux through the SQUID in quantized amounts
Our device is just a RSJ device… so no capacitor
Can see relation with current change with an applied mag field (a)
Implies a change in voltage with application of magnetic field
Interference – similar to what happens in optics!
Utilize the SQUID Pattern for characterizing voltage response and a function of applied magnetic field.
Focus on steepest slope on SQUID pattern and go to DC.
Basically focuses on one point and applied B-field causes oscillation of voltage.
Means that we have a connection between voltage oscillation and external magnetic field.
(Alter image so it is clear that we are inducing a B-field into the DEVICE)
Compact instruments normally used for these types of measurements into essential components.
6.2lbs
Circuitry that utilizing functions we need!!!!!
-Low Noise pre-amplifiers
-Slow 1 Hz oscillator (triangle)
-20Hz LP filter
-Must electrically isolate from outside noise or will influence signal
Magnet produces Fraunhofer for specific SQUID device
Filters: Understand where there might be weaknesses in noise development
Placement: shielding purposes
MEG – Helium dewar on your head