New quantum receiver the first to detect entire radio frequency spectrum

Post by pmorici » Sun, Feb 07, 2021, 3:56 AM UTC

superkuh wrote: post #49

elmo2you wrote: post #33

Maybe it's just me, but this reads to me is as a big load of cleverly worded (misleading) statements that say little, yet make all kind of vague suggestions. I don't know any details about this particular tech, but I think the article says this can detect radio waves over a relatively large spectrum (0Hz..20GHz) simultaneously. It doesn't mention anything about focusing on any particular frequency, or even if it can…

It's not an antenna like I thought at first. It's a tuner with 4 MHz instantaneous bandwidth and a very wide tuning range, https://arxiv.org/abs/2009.14383 - the actual (laser intensity) measurements are done within the RF electrical field above a coplanar waveguide track on a PCB. It's a cool RF tuner. But it still need a real, full size, antenna. It's also not clear to me if they can get the phase informations out…

Post by pmayrgundter » Sun, Feb 07, 2021, 4:33 AM UTC

ShinyRice wrote: post #52

pmayrgundter wrote: post #46

This article got me interested to learn more. There's a related phenomenon called the Rydberg Blockade[1], wherein a group of Rydberg atoms can be tuned to multiple quantum states and because of their large radii, form a coverage area over space in which those quantum states are excluded for other particles (by Pauli exclusion?). There's work to create large arrays, 1D and 2D of tens to hundreds of elements, of Rydbe…

A bigger problem in getting power from fusion is dealing with the resulting neutrons. You can't redirect them out the exhaust, so it's energy you've lost (unless you harness the thermal power of the reactor rather than straight up using it for thrust); they bombard the reactor and can cause regular matter to become radioactive...

Post by mindcrime » Sun, Feb 07, 2021, 5:13 AM UTC

madengr wrote: post #45

TheSpiceIsLife wrote: post #39

Earlier quoted context omitted.

The article I linked claims: A fractal antenna's response differs markedly from traditional antenna designs, in that it is capable of operating with good-to-excellent performance at many different frequencies simultaneously. Is this inaccurate? The associated electronics are obviously necessary too.

Fractal antennas are mostly snake oil. You’ll always see then driven against a large counterpoise (ground plane), as the counterpoise becomes the radiator. You can make use of Chu’s limit without resorting to fractals. https://en.m.wikipedia.org/wiki/Chu–Harrington_limit

Post by infogulch » Sun, Feb 07, 2021, 6:28 AM UTC

pmayrgundter wrote: post #53

ShinyRice wrote: post #52

Earlier quoted context omitted.

A bigger problem in getting power from fusion is dealing with the resulting neutrons. You can't redirect them out the exhaust, so it's energy you've lost (unless you harness the thermal power of the reactor rather than straight up using it for thrust); they bombard the reactor and can cause regular matter to become radioactive...

I think that's true for the easier to ignite reactions like D-T, but there are others that are aneutronic, eg Proton+Boron. It's much harder to initiate, but the fuel is cheap and the energy output higher. "Aneutronic fusion loses much of its energy as light... Since X-rays can go through far greater material thickness than electrons, many hundreds or thousands of layers are needed to absorb the X-rays." https://en.m…

Post by pmayrgundter » Sun, Feb 07, 2021, 7:05 AM UTC

infogulch wrote: post #57

pmayrgundter wrote: post #53

Earlier quoted context omitted.

I think that's true for the easier to ignite reactions like D-T, but there are others that are aneutronic, eg Proton+Boron. It's much harder to initiate, but the fuel is cheap and the energy output higher. "Aneutronic fusion loses much of its energy as light... Since X-rays can go through far greater material thickness than electrons, many hundreds or thousands of layers are needed to absorb the X-rays." https://en.m…

What if the fusion container was an x-ray laser? Could it induce fusion, where emitted xrays are in phase with the laser? I can imagine that an extreme high energy, directable, phase aligned, giant laser power source could be pretty useful.