September 2, 2006

Clarke group research in Physics Today

Posted by Arcane Gazebo at September 2, 2006 7:35 PM

I'm late noticing this, but the August issue of Physics Today has an article (subscription required) about axion detection experiments, which mentions some work being done in the Clarke group:

An amplifier whose noise temperature approaches the quantum limit would dramatically improve the sensitivty and search rate of the axion experiment. To achieve that goal, our collaborator John Clarke and his coworkers at the University of California, Berkeley, developed a new amplifier based on a microstrip-coupled superconducting quantum interference device in 1996. Unlike the noise behavior of heterojunction transistor amplifiers at low temperatures, the intrinsic noise of the SQUID is proportional to the physical temperature, the origin being thermal noise in shunt resistors across the SQUID's Josephson junctions. Cooling reduces the noise until it flattens out within 50% of the quantum limit. Newer SQUID designs with micro-cooling fins that enhance the coupling of electrons to the lattice are pushing these devices closer still to the quantum limit.

Unfortunately the full article is only available to subscribers, but those of you who are APS members can check it out. The quantum-limited amplifier is pretty cool and some groups are looking at using it for qubit experiments as well. Ironically, the vacuum pumps required to cool this low-noise amplifier are really loud, and so having to work in the same room as this experiment is sort of annoying.

Tags: Lab, Physics, Science
Comments

I vaguely remember looking at that article.

Maybe my response should be, "That's cute, but has your boss's research ever been covered by ESPN?" :)

I wish I were paying more attention a few months ago when his name came up during condensed matter gossip, but by the time I realized, I pretty much missed it aside from the name being mentioned.

Posted by: Mason | September 2, 2006 11:19 PM

"Ironically, the vacuum pumps required to cool this low-noise amplifier are really loud, and so having to work in the same room as this experiment is sort of annoying".

I hate this, the valve on our pulse tube cooler also makes a lovely noise on top of the vacuum pump every 3 seconds which i think sounds alot like Darth Vader on speed, it is so nice to leave at the end of the day. Of course, right now the whole thing is broken and doesn't make any noise at all.

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Posted by: jillian | August 29, 2007 10:41 AM
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