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2Physics Quote:
"The exchange character of identical particles plays an important role in physics. For bosons, such an exchange leaves their quantum state the same, while a single exchange between two fermions gives a minus sign multiplying their wave function. A single exchange between two Abelian anyons gives rise to a phase factor that can be different than 1 or -1, that corresponds to bosons or fermions, respectively. More exotic exchanging character are possible, namely non-Abelian anyons. These particles have their quantum state change more dramatically, when an exchange between them takes place, to a possibly different state." -- Jin-Shi Xu, Kai Sun, Yong-Jian Han, Chuan-Feng Li, Jiannis K. Pachos, Guang-Can Guo
(Read Full Article: "Experimental Simulation of the Exchange of Majorana Zero Modes"

Sunday, February 18, 2007

"Interferometric Detection of Gravitational Waves :
4 Needed Breakthroughs" -- David Shoemaker

David Shoemaker standing next to the full-scale interferometer testbed in LIGO MIT Lab (photo courtsey: LIGO MIT Laboratory)

[We asked leading scientists of various fields to point out 5 needed breakthroughs that they would like to see in their own field of research. We are starting this feature today with the input from Dr. David Shoemaker.

David Shoemaker played an important role in both the R&D effort and commissioning of the joint Caltech-MIT LIGO laboratory for the detection of gravitational waves. Currently, he is Director of the LIGO MIT Laboratory at Kavli Institute for Astrophysics and Space Research, MIT. He also leads the LIGO research group on Advanced LIGO Development.

-- 2Physics.com team]

"Four, rather than five, breakthroughs would satisfy me:

- A means to significantly reduce (through changes in formulation or process) or circumvent (via an alternative optical topology) the thermal noise in the reflective dielectric coating on the test masses (and in the bulk of the test masses as the next step!)

- Successful application of prepared states of light to improve the sensitivity of full-scale gravitational-wave detectors while keeping circulating power at technically acceptable levels.

- A practical application of a method to regress out (via e.g., an array of seismometers) or reduce (via e.g., a mechanical design) the gravitational gradient noise, allowing lower frequency operation on the ground.

- ....and, slightly different in character: The first direct detection of a gravitational wave."

Relevant Links:
LIGO Laboratory     LIGO MIT Laboratory    LIGO Science Collaboration

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At 11:25 PM, Anonymous Eric Snyder said...

I feel there should be another LIGO Laboratory at some other corner of USA (say, Maine or Alaska or both if you have fund). It would be better option than upgrading current interferometers at Hanford and Louisianna because you can gain more SNR from a better coincidence operation.

Once I told this to a professor at Louisianna State University but he did not pay any attention to my comment.

At 11:42 PM, Anonymous Anonymous said...

Dr. Shoemaker, I do not quite understand how LIGO works but, as an Optomechanical engineer, I can only understand some issues of Optics. Once I heard in a conference in U. Florida, Gainesville that your major problem is Thermal lensing. In fact, I got the impression (from the speaker) as if it was the only problem
why GW has not been discovered yet.

Is that still an issue that needs to be solved?

At 8:02 PM, Anonymous Thomas G. Coogan said...

I teach Physics in Seattle. I visited LIGO Hanford observatory and took a guided tour led by Dr. Rick Savage and also met Dr. Fred Raab, Director.

All LIGO scientists look very enthusiastic. Looking forward to the first detection of GW.

At 2:33 PM, Anonymous dbh said...

Why would the passing GW not distort the laser beam(s) the same way it distorts the rest of the apparatus, making the measurement of GW-induced displacements impossible?


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