Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Quantum fluctuations have been shown to affect macroscopic objects

nature.com

Post reply on HN
Print view View original

21–28 of 28 posts

Re: Quantum fluctuations have been shown to affect macroscopic objects

#21

Post by blurbleblurble »

stallmanite wrote: post #4
knodi123 wrote: post #3

Earlier quoted context omitted.

Such conceptually dense language! Isn't the average amplitude of every wave just zero?

Hmm, at least with an audio waveform one can have a DC offset wherein the average is not zero.

The DC offset can be considered as approximating a low frequency component that is so low frequency, relative to the measurement window, that it appears to be constant.

I think in the case described here, the zero average amplitude thing has to do with something a little bit different.

Re: Quantum fluctuations have been shown to affect macroscopic objects

#23

Post by plafl »

Physicist help needed: From my near null knowledge of quantum mechanics it seems they decrease randomness in phase and amplitude measurement by increasing uncertainty in mirrors position. So, this is interesting because the mirrors are macroscopic objects that interacted with the light in a rather simple way and conditions. On the other hand... Don't they require the mirror position in a well determined position to measure the gravitational waves?

Re: Quantum fluctuations have been shown to affect macroscopic objects

#25

Post by Chris2048 »

perl4ever wrote: post #2

"A special case of squeezed light, known as the squeezed vacuum, forms when the average amplitude of the light is zero." I love this. Don't ask me what it means.

I found an article with this description:

  Exotic as the name seems, squeezed states are just Heisenberg’s uncertainty principle in action. In quantum optics, a light field is described by two “quadratures,” one for phase (P) and one for amplitude (X). Per Heisenberg, the minimum uncertainty of those two quadratures in a given measurement is given by the relation ΔXΔP = ħ/2. In other words, for a given measurement, the better you know the phase, the more potential error there is in the amplitude, and vice versa.
  
  For a coherent state, such as a laser field, the phase and amplitude uncertainties are equal, giving rise to a circularly symmetric “fuzzball” of potential error between the two quadratures. But using nonlinear-optics techniques, the circle can be “squeezed” into an ellipse. That means that uncertainty in one quadrature—the one that’s relevant to your sensor—can be reduced, while the uncertainty in the other, less relevant quadrature are increased.
-- https://www.osa-opn.org/home/articles/volume_30/september_20...

Re: Quantum fluctuations have been shown to affect macroscopic objects

#26

Post by tadhgf »

The_rationalist wrote: post #24
martinclayton wrote: post #22

Out of context perhaps, but rings true: "...SQL is a direct consequence of the Heisenberg uncertainty principle..."

I don't understand yet I know the uncertainty principle, would you mind to explain?

It's a joke about about SQL databases misbehaving, not physics

Re: Quantum fluctuations have been shown to affect macroscopic objects

#28

Post by c1ccccc1 »

plafl wrote: post #23

Physicist help needed: From my near null knowledge of quantum mechanics it seems they decrease randomness in phase and amplitude measurement by increasing uncertainty in mirrors position. So, this is interesting because the mirrors are macroscopic objects that interacted with the light in a rather simple way and conditions. On the other hand... Don't they require the mirror position in a well determined position to m…

They are increasing the precision of the phase while decreasing the precision of the amplitude. Since the amplitude of the light determines how hard it pushes on the mirrors, this has the side-effect of also making the positions of the mirrors more uncertain. To get the most accurate measurement possible, I'd guess that they would squeeze the light until getting any additional precision in the phase was not worth the added noise in mirror position.
Post reply on HN