Questions tagged [noise]

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2 votes
2 answers
46 views

In what respect does the wave pattern of a noise and music differ?

Does the wave pattern of musical sounds contain only harmonics (other than the fundamental frequency) while noise contains random overtones (that are not harmonics)?
3 votes
1 answer
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Dephasing noise as a decoherence model - Effect on a generalized GHZ state

Some input: Consider a decoherence process modelled by $$\mathcal{E}\left(\rho\right)=p_0\rho+(1-p_0)\sigma_z\rho\sigma_z$$ with $p_0=(1+e^{-\gamma t})/2$. One can readily find that this leads to $\...
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Minimum Observable Offset Frequency in Leeson's Formula

It has been argued in some publications that the age of the universe represents a lower limit on observable frequencies (in their paper, corresponding to a value of $10^{-17}$ Hz). The authors do not ...
1 vote
0 answers
32 views

Why does metal wire make noise but not string [closed]

why when I vibrate metal string it make noise but when I vibrate string it no make noise?
1 vote
0 answers
32 views

Applying a simple noise model to the ghz state

I want to calculate the effect of a specific noise model on the GHZ state but fail to do so. I think I am missing some basic rules established for working with operations on density matrices. More on ...
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1 vote
0 answers
53 views

Derivation of Heisenberg-Langevin equations for an atom coupled to a reservoir of harmonic oscillators

I have been working on the paper of A. Lezama on the "Numerical investigation of the quantum fluctuations..." (2008) and been trying to replicate their derivation and simulation. However, I ...
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5 votes
1 answer
130 views

What's the smallest signal to noise ratio for which a signal has been extracted?

Suppose we have some physical variable $y$ that is changing in some way and we want to detect this change in the presence of noise (e.g. white noise) in that same physical quantity. For example $y$ is ...
1 vote
1 answer
50 views

Magnetic field modeling with noises

I am trying to make a 3d grid of a magnetic field with some noises (which will be added to the ordinary field) for a computer simulation. I have the formula for the ordinary field, also I am using a ...
3 votes
1 answer
21 views

Experiment preparation - Box to reduce background photons noise

I am planning to perform experiment with a photomultiplier tube (PMT) in my lab. The system is not large, with a length scale of about 10 cm. I am looking to reduce the background photons noise as ...
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5 votes
0 answers
66 views

Does 5G affect your physics experiment?

Our institution wants to lease a nearby roof for a 5G mast. Has anyone experienced the installation and operation of telecoms infrastructure - particularly 5G - significantly affecting physics ...
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0 votes
0 answers
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Random telegraphic noise and Lorentzian noise power spectral density

Following the example of the Lorentzian noise power spectral density shown above (ref), I would like to clarify the following: In the first figure (labeled by (c)), May I please know why the constant ...
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1 vote
1 answer
55 views

Derivation of sound wave propagation equation

I am trying to derive the sound propagation equation like this. $$\frac{\partial^2 P'}{\partial t^2} = c^2\left(\frac{\partial^2 P'}{\partial x^2}+\frac{\partial^2 P'}{\partial y^2}+\frac{\partial^2 P'...
2 votes
0 answers
46 views

How do different $|\text{Alive}\rangle+|\text{Dead}\rangle$ kind of states behave under decoherence?

I am looking for literature that investigates said behaviour for spins. So far I found many papers on how to measure the macroscopicity of states and therefore a classification of macroscopic states. ...
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1 vote
0 answers
35 views

Can we collapse noises by reducing temperature? [closed]

Is it possible to reduce noises to any extent by decreasing temperature? please give answer using reference to article or website.
1 vote
1 answer
33 views

Why wireless radios start making buzzing noise when I switch on some electrical appliances?

This question has possibly been asked a numerous number of times already, by many people in many places, but nowhere can I find a precise answer to my precise question. When I turn on, say a ceiling ...
0 votes
0 answers
20 views

How to add Gaussian noise to light wave

I want to find a method that can add independent Gaussian noise to different incoming light waves; Or find a noise light source that can emit light with Gaussian noise.It would be great if there were ...
1 vote
1 answer
20 views

What is the fractional frequency stability of a thermal damped harmonic oscillator?

Suppose I have a lightly driven (classical) damped harmonic oscillator at temperature $T$. Suppose $\omega$ and $Q$ are specified as well as the mean energy $\bar{E}$ in the oscillator due to the ...
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3 votes
2 answers
121 views

What limits mechanical watch precision? [closed]

It seems like good mechanical watches gain or lose +/- a few seconds per day. 5 s/day corresponds to a fractional frequency stability of $5\times 10^{-5}$. What limits this stability? Obvious ...
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0 votes
1 answer
82 views

Is gravity of matter similar to temperature?

Apart of general relativity and the quantum theory postulate o gravitons I am looking for an alternative quantum physical interpretation of gravity of matter? Watching this short video-cut from Dyson'...
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0 votes
1 answer
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Why does a non-gaussian distribution imply noise in LIGO?

So I'm trying to understand why do we expect a non-gaussian distribution to imply correlation in LIGO? Like how do we know the default noise distribution is gaussian? I am concerned about coordinate ...
0 votes
0 answers
24 views

What processes in nature exhibit blue and violet noise?

I am interested in noise colors exhibited by all kinds of natural processes, such as by solar flares, seismic earth waves, brain activity, fluctuations in deep sea water velocities, etc. These ...
0 votes
0 answers
22 views

Improve Spectrometer SNR

I am trying to perform optical emission spectroscopy but I have very low light intensity. Without increasing the intensity, can I improve the SNR somehow? I am already close to the saturation point of ...
0 votes
0 answers
48 views

Why do we need different models of thermal relaxation noise for $T2>T1$ and $T2<T1$?

Noisy quantum channels are in generally described by the operator-sum representation with kraus operators (see eg. in Nielsen,Chuang). But for the thermal relaxation error different modeling used for ...
1 vote
0 answers
40 views

Is this a good use of the convolution?

I would like to replicate the real response of an instrument to some signal. Here's what I have in mind: I generate some ideal signal. I then add Gaussian noise to it to produce a realistic signal s(t)...
3 votes
2 answers
65 views

Is there a fundamental lower bound to resistor precision?

The resistor noise index provides a lower bound to how precise a resistor can be measured, even using ideal instrumentation. Effectively, it even makes no sense to define the resistance any more ...
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3 votes
1 answer
61 views

Why can thin sponge lining soundproof earmuffs but not walls?

Every webpage that I can find says that sponge is bad soundproofing material for walls because it's light and physics says that materials with more mass isolate better. So my question is how come thin ...
0 votes
0 answers
24 views

How does microscopic noise appear in macroscopic description

We know that noise in the position of some particles translates to a translational diffusion constant in their macroscopic description. We also know that noise in the orientation of some particles ...
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3 votes
0 answers
71 views

Spherical harmonics with 2 cosmological probes : considering $a_{\ell m, photo}$ as a constant and $\hat{a}_{\ell m, spectro}$ as an estimator

I am in cosmological context where the survey on which I am working has 2 probes : a photometric galaxy clustering ($GC_{ph}$) probe and a spectroscopic galaxy clustering ($GC_{sp}$ probe). We use an ...
0 votes
0 answers
41 views

Convert noise measurements that used 3-dB exchange rate (ER) to 5-dB

NIOSH uses 3-dB as the exchange rate (ER) for sound measurement, while OSHA uses 5-dB as the ER. Is there any way to convert the measurements using these two approaches? If yes, how can we do that? I'...
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11 votes
2 answers
2k views

What causes this strange noise in a pair of walkie-talkies?

Let us suppose that Bob and Alice both have walkie-talkies. They are both 3m apart from one another. Alice pushes her walkie-talkie to speak but instead of speaking, she starts walking toward Bob. ...
0 votes
1 answer
118 views

What does photon-limited imaging mean?

The following link is about Photon-Limited Imaging, https://engineering.purdue.edu/ChanGroup/project_QIS.html. Is there any definition of Photon-Limited Imaging. From the paper Photon-Limited Object ...
0 votes
0 answers
29 views

Is it possible to obtain noise level in electrons using only one camera?

In the link, https://www.photonstophotos.net/GeneralTopics/Sensors_&_Raw/Sensor_Analysis_Primer/Photon_Transfer_Curve.htm there is one figured called Standard Photon Transfer Curve – Multiple ISOs ...
-1 votes
2 answers
107 views

Does sound travel through FINGERS?

as we know that sound's speed is fastest in solid (and slowest in air). QUESTION - what is the reason when we close our ears and don't really hear loud noises though sound travels faster in solids?
3 votes
1 answer
171 views

Consistency of Lindblad-type operator evolution equations

One frequently comes across Lindblad-type operator evolution equations in the Heisenberg picture of the form $$ \frac{\mathrm{d}}{\mathrm{d}t} A =\mathcal{L}^{\dagger}(A), $$ where the adjoint ...
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3 votes
1 answer
52 views

Frequency dependence of noise at advLIGO

Here's a picture showing how different sources of noise affect the sensitivity of LIGO I'm trying to understand the frequency dependence of each curve. I'll specifically focus on seismic noise, ...
0 votes
1 answer
158 views

Removing $1/f$ noise with lock-in-amplifiers

On the Wikipedia page for 1/f noise (at the bottom of the page) it suggests the noise can be reduced if the signal of interest is at DC. DC signals suffer from significant 1/f noise, so one method of ...
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57 votes
3 answers
7k views

Why doesn't oil produce sound when poured?

I've noticed that unlike other liquids, when pouring olive oil for example, I don't hear any sound at all from it. Usually you can hear an audible sound as a cup gets filled with water, as the sound ...
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2 votes
2 answers
63 views

Can there be multiple shot noise sources? For example: laser & camera

Suppose you have a system consisting of a laser, a filter (with transmission $T$), and a camera. To my understanding, both the laser and the detector produce shot noise. Is that correct? For a camera ...
1 vote
4 answers
82 views

Can a metal sheet roof be vibrated at audio frequencies?

So I'm renting a cheap place for now due to certain circumstances. Problem is outside noise is excessive because there is no ceiling and the roof is only a metal sheet... Lately I play white noise to ...
0 votes
1 answer
52 views

Difficulty bounds in a white noise model

Suppose we make a measurement in a real/virtual experiment for which the noise is given by a white noise (Gaussian) model. Suppose also that we have a very good filter or machine learning (ML) model ...
5 votes
2 answers
240 views

Why does shot noise rise with frequency in LIGO sensitivity?

In plots of the sensitivity of the LIGO interferometer, photon shot noise is the dominant noise source at the high frequency end, e.g. this graphic: It appears to rise roughly in linear proportion ...
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0 votes
1 answer
446 views

Commutator of an operator with its Hermitian adjoint in linear quantum systems

I have a commutator of a single-mode photon field operator $\alpha$ with its Hermitian adjoint $\alpha^{\dagger}$. [$\alpha$, $\alpha^{\dagger}$] When this commutator gives a negative value, $\alpha$ ...
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4 votes
3 answers
155 views

Are stationarity, Markovianity and Gaussianity sufficient conditions to ensure that the random force on a Brownian particle is delta correlated?

In the Langevin model, if we make the assumption that the random force $\eta(t)$ acting on the Brownian particle is a stationary, Markovian, and gaussian process, does it automatically ensure that the ...
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4 votes
0 answers
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Pink noise and averaging

Disclaimer: I am aware this is somehow at the boundary between physics and statistics, but I have the impression that it is more likely that somebody doing/studying physics, rather than statistics, ...
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2 votes
1 answer
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Is this intuitive understanding of "averaging over all realizations of a noise" correct?

Consider a continuous random variable $\eta(t)$ such that $$\langle \eta(t)\rangle=0, \forall t$$ where the average $\langle ...\rangle$ is taken over all possible realizations of the noise at any ...
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5 votes
0 answers
70 views

Why do I hear static when I plug in my earphones incorrectly?

I use simple earphones which are wired with my laptop. Most of the times I unconsciously plug them in without looking and at times instead of going in the port they touch the laptop body near the port ...
0 votes
4 answers
491 views

Deterministic and stochastic chaos

I have a question about chaos, but first a foreword of what I understood. Noise refers to the random variation of values. Usually unwanted, noise causes a measurement to fluctuate over time. Chaos ...
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0 votes
1 answer
103 views

Relationship between intensity and sound level

So I know that for every tenfold increase in intensity, the sound level increases by 10 dB. So if the intensity is increased by a factor of 100000, the sound level increases by 50 dB. I also know that ...
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1 vote
1 answer
211 views

Noise Cancellation - Destructive Interference

We know that active noise cancelling headphones work by playing a signal in your ear which is 180º out of phase with the ambient noise. If we compare the two waves, the peak in one wave is completely ...
0 votes
2 answers
300 views

Can unjammable radio communication be achieved by transmitting an error-correcting code of high-energy pulses in a secret, unpredictable pattern?

Signal jamming seems like an annoyingly simple way to sabotage a lot of interesting ideas. It has historically been used to block reception of propaganda broadcasts, and also to ruin military ...

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