New Chip For Square Kilometer Radio Telescope

An anonymous reader writes "ZDNet Aus reported on a new low-noise chip that could help in building the $1.6B Square Kilometer Array, the world's largest radio telescope. Wikipedia claims the telescope will be 50 times as sensitive as current instruments. It will have a resolution able to detect every active galactic nucleus out to a redshift of 6, when the universe was less than 1 billion years old and way crazy. It will have the sensitivity to detect Earth-like radio leakage at a distance of several hundred to a few thousand light years, which could help greatly with the search for extraterrestrial life. The chip's designer, Prof. Jack Singh, commented on the chip's ability to help with quantum computing research, due to its ability to operate at millikelvin temperatures, necessary to prevent quantum decoherence."

"Wikipedia claims"

[LMacG]

That claim actually comes straight from the Square Kilometer Array website [skatelescope.org].

Low noise

[evanbd]

It's not explained in the article, but the reason for the very low temperature operation is resistor thermal noise [wikipedia.org]. Basically, any resistor (or anything with vaguely resistor-like properties, for example the radio antenna itself) creates "thermal noise" from the thermally-induced effects of electrons bouncing around. At room temperature (300K), that noise is 4E-21 watts per 1Hz bandwidth -- or about -130dBm on a fairly narrow 10kHz bandwidth. The noise generated varies linearly with temperature, so if the entire input amplifier is operated at 300mK instead of 300K, you get an extra 30dB of signal-to-noise ratio, which is substantial when you're looking for very very weak signals.

Fun fact: with a $5 op-amp, a few resistors, and an audio amplifier, you can create your own, entirely quantum, true white noise source from the same effect. Guaranteed good for cryptographic random number generation, impressing your friends, and preventing dates!

Re:They'd better not waste it on SETI

[SixByNineUK]

The SKA has 5 key science goals, one of them, called 'The cradle of life' is aimed at looking for possible life in other star systems, but I believe it is mainly focusing on studying the formation of earth-like planets (to better understand our own). I think that any real SETI efforts will be done as a sort of 'piggyback' on other projects (Although I don't think the scheduling arrangements are anywhere near ready yet!).

What about LOFAR?

[StarfishOne]

"The world's largest radio telescope"? I think they're somewhat forgetting some of the competition:

http://www.lofar.org/ [lofar.org]

But it might depend a bit on how one bends definitions (min/max distance between receivers etc.)..

"The antennas are simple enough but there are a lot of them - 25000 in the full LOFAR design. To make radio pictures of the sky with adequate sharpness, these antennas are to be arranged in clusters that are spread out over an area of ultimately 350 km in diameter. (In phase 1 that is currently funded 15000 antenna's and maximum baselines of 100 km will be built). Data transport requirements are in the range of many Tera-bits/sec and the processing power needed is tens of Tera-FLOPS."
http://www.lofar.org/p/geninfo.htm [lofar.org]

Re:redshift of 6?

[Astro Dr Dave]

Redshift (z) is a unitless ratio. It used as a (nonlinear) measure of distance in extra-galactic astronomy and cosmology.

The quantity 1+z is the ratio of the scale of the universe now to the scale of the universe at that redshift. Our local area (Milky Way galaxy) corresponds to z=0. So, for example, the universe was 7 times smaller at z=6, and the density of intergalactic gas is proportional to (1+z)^3.