Questions tagged [low-temperature-physics]

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How do we do experiments on gases at zero Kelvin?

We say that at temperatures very close to absolute zero (nano or pico Kelvin) there is no gas, so how do we do experiments on gases at zero Kelvin, and why is Bose-Einstein described as a gas? 1995 – ...
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How much energy does it cost to cool an atom to close to 0K?

I read that for many Quantum experiments with Atoms it is necessary to cool them to close to $0K$. How much energy does that cost roughly? Is there a formula which gives a lower bound?
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Heisenberg's uncertainty principle in frames of reference with different velocities

The Heisenberg's uncertainty principle \begin{align}\Delta x \Delta p \geq \frac{\hbar}{2},\end{align} states that two canonically conjugate variables can't be measured simultaneously with arbitrary ...
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Is superconductance restricted to an extremely low temperature? Or can it be effectively replicated using some other technique?

A type of electrical amplifier is proposed in which only magnetism and it’s analogous current exists for the most part. There is no voltage and no wattage (to speak of) in which electricity has to ...
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Why liquid helium boils as its temperature is lowered?

Water boils when heated. Liquid helium boils when cooled. Not only that. It boils initially and then stops. Why?
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What is cold wind?

As per my understanding, temperature is the movement of particles in an environment. A highly energetic environment where particles possess high energy has a high temperature, and low energy means low ...
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At absolute zero temperature, we see that the electrical resistivity of a metal is not zero - Why? [closed]

I do know that for a perfect conductor, the electrical resistivity is zero at absolute zero temperature. But for an imperfect conductor (e.g. that we use in daily life) it is not zero even at $T=0^{\...
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Gravitationally-driven electrical potential differences in conductors

This question asks Free electrons in a metal are attracted by gravity towards Earth. So why don't they lay down to the bottom of the conduit, like sediment at the bottom of a river? The current ...
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How $^3\text{He}$ atoms remove thermal energy from surrounding environment in dilution refrigerator?

I am trying to understand how a dilution refrigerator works. I understand that $^3\text{He}$ atoms are pumped out of the diluted phase and to reestablish an equilibrium, new $^3\text{He}$ move there ...
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What happens to isothermal compressibility at zero temperature?

In chapter 11 of his book on thermodynamics, Callen states that Nernst postulate implies the isothermal compressibility (denoted as $\kappa_T$) of any system vanishes as its temperature approaches ...
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As of 2021, what is the latest record for lowest temperature?

From what I understand in this article, absolute zero(0 kelvin) is an impossible task. They state that the lowest temperature achieved in the laboratory was 0.1 nanokelvin. The lowest temperature ...
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Markov approximation at low temperatures

I'm interested in a two-level system in contact with a reservoir of harmonic oscilators, described by the following Hamiltonian: $$ \hat{H}=\hat{H}_S+\hat{H}_R+\hat{H}_{RS}=\hbar\omega_0\hat{a}^\...
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How to perform experiments near absolute zero temperature when the background temperature of the universe is 2.7 K?

The cosmic microwave background (CMB) radiation as a remnant from an early stage of the universe (Big Bang) is filled all space and has a thermal black body spectrum at a temperature of $2.72548±0....
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MOSFET current at very low temperature (4K)

I am trying to model the current at low T. To do so I need to compute the integral of fermi dirac statistics multiplied by the conductivity, with respect to energy: My problem is that I cannot ...
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Are there substances that behave as perfect conductors but not superconductors?

Does there exist substances which below a certain temperature becomes as a perfect conductor but not a superconductor? A superconductor is both a perfect conductor as well as a perfect diamagnet. If ...
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What happens to the electrons mobility when metals get cooled down?

I know conductivity increases, but what happens to the electrons on the inside?
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Pomeranchuk Effect

Pomeranchuk effect poses a paradox of order by disorder phase-transition. The liquid Helium-3 is in a liquid form close to absolute temperature. For high enough pressure, as you increase the ...
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Inverse temperature and Lennard-Jones model

I am a mathematician and I am trying to understand the intension behind the inverse temperature and the activity (or intensity). Consider e.g. the Hamiltonian [with (12,6)-Lennard-Jones pair potential]...
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RG for Interacting Fermions - Shankar's Review

I want to ask a question about a rather famous review paper on RG by Shankar. On page 92-93 of this paper, Shankar provides a version of RG for spinless fermions in $d=2$ dimensions with a soft cut-...
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Calibration of Hall Effect Measurement using Standard Reference Material (NIST)

I would like to calibrate a low-temperature Hall effect measurement using a Fe SRM. Are there any standardized Hall measurements of SRM's available?
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Vortex solution of Laplace equation (XY model)

The hamiltonian of XY model, which is closely connected with BKT - transition is following: \begin{equation} H=\frac{J}{2} \int \text{d}^2 r \, \nabla \varphi \cdot \nabla \varphi, \quad \...
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What are good books and other resources to study the Cryogenics?

I'm beginner in cryogenics. Also please suggest something which will be useful for study of Electronics at Cryogenic Temperatures.
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Do metals at low temperature follow Ohm's law?

I think metals at low temperature do not follow Ohm's because of superconductivity. Is it true? What about metals at high temperature?
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Can a permanent magnetic become too cold to function?

I have heard that it's possible for a permanent magnet to become too hot to function, especially if it reaches melting temperature however I cannot find much on the affect of cooling a magnet ...
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2 votes
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Understanding why a substance cannot be at $0K$

I am trying to understand why it is that a substance cannot have a temperature of exactly 0K. My text book's explanation is that since internal energy is the sum of the kinetic energies of the ...
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Reaching 0 K in a "Finite number of steps"

Let me preface this by saying that I don't really like the third law of thermodynamics very much. Its not that I believe its not true, its just that it feels non rigorous, all its different ...
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Is it really true that valence band is completely filled at zero temperature?

Is it really true that valence band is completely filled at null temperature? Indeed, I would think that if we apply an electric field, this would give some energy to the electrons from the valence ...
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How do we cool gases to the $mK$ range?

When we set new records for coldest temperature in the universe, we usually do it with gases (see: https://physicsworld.com/a/millikelvin-cooling-of-large-molecules-is-no-myth/) How do we pull this ...
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Why is a liquid nitrogen canister not cold on the outside when inside the temp of the sealed liquid is -320F? [closed]

...or IS the inside temperature ambient temperature? Surely the insulation of the container is not sufficient to seal in that cold? I.e. if you had an unsealed bowl of liquid nitrogen with the same ...
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What happens to a liquid nitrogen canister under pressure if left at room temperature? Will it eventually explode? Or forever stay cold?

If I put a strong, sealed container of liquid nitrogen on a table at room temperature, will it always stay cold? Or will it slowly heat up until the canister bursts? Assume it is an extremely strong ...
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Does quantum gases obey ideal gas equation $ PV= nRT$?

At extremely low temperature, does an ideal gas of bosons or fermions obey the ideal gas equation, $PV= nRT$?
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Would there be any current if an electric circuit is cooled to absolute zero?

My question is if I got a superconductor and cool it to absolute zero at least measurable by today's tool, it should have no electrical resistance but then would there be any current when there is a ...
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Why is -273.15 °C the low temperature limit for the universe? [closed]

According to Ideal Gas Law the lowest temperature of an ideal gas can be $-273.15 °C$. This temperature is also considered the lowest temperature in the universe. But it is the lowest possible ...
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Is there a temperature-pressure phase diagram of carbon dioxide for the lowest temperatures and pressures?

The image above will probably be well known to visitors of Wikipedia on CO$_2$. But is there a temperature-pressure phase diagram of CO$_2$ for still lower temperatures and lower pressures as well ?...
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Is there a maximum frequency at which hysteresis appears?

If a ferromagnetic material is immersed in an alternating magnetic field at frequency $\omega$, the material will follow a hysteresis cycle at that frequency. But if that frequency is high enough, the ...
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Canonical ensemble near absolute zero

In the canonical ensemble for an ideal gas of $N$ bosons, the partition function for $T\to 0$ scales like $$Z\sim e^{-\beta\epsilon_0N},$$ when $\epsilon_0$ is the lowest (non-degenerate) single ...
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Do photons have a minimum energy in relation to the expansion of the universe?

As the universe expands, background photons lose energy. Can that keep happening? After all, you can never reach zero temperature. So what happens to photons in the limit?
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Is there any positive temperature from which superconductivity ceases?

From what I understand about superconductivity, it is due to a coupling between Cooper pairs and phonons. At the absolute 0, there is no phonon, so I assume superconductivity cannot exist at that ...
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What are some empirical ways to estimate the absolute 0 in temperature?

Back in the 1600's and 1700's, people could estimate the existence of an absolute 0 in temperature by using the ideal gas law $PV=nRT$. By holding $P$ and $n$ constant and by observing how much gases ...
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Can't we stop the time? [duplicate]

Time is called as a measurement of difference between two or more incidents. So if we stop happening incidents can't we stop the TIME? Eventhough it's impractical, I mean if we reduce the temperature ...
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3 votes
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Is the $\lambda$ point in superfluid helium understood?

When liquid helium is cooled below a certain temperature, it undergoes a second phase transition from He I to He II. The specific heat spikes at the famous lambda point. Is this spike in the specific ...
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Is there any example of a real-life system which violates the "third law" of thermodynamics while remaining at equilibrium?

I assume the following statement for the "third law" of thermodynamics: $$\lim_{N \to \infty} \lim_{T \to 0} \frac{S}{N} = 0 \tag{1}\label{1}$$ That is to say, I am considering those systems with a ...
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Why does Aquafina explode when frozen?

I put two Aquafinas in the freezer this morning "for a few minutes" but then forgot to take them out. Tonight, I opened the freezer. Both cans had exploded; on one, the top was blown off; on the ...
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What is the radiative cooling rate at extremely cold temperatures?

Consider a spherical object in empty space, in the far future where the CMB can be entirely neglected. What is the cooling rate as it approaches radiative equilibrium? Here is what I got so far: The ...
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Splitting of Forces at Low Temperatures?

Since the electroweak force split from the strong force during the electroweak epoch then the electroweak force split into the electromagnetic and weak force during the quark epoch, is this an ...
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Wind speed and molecule drift speed

My question regards this answer, more precisely this assertion: If all the air molecules, by some strange coincidence, all moved in the same direction 2 things would happen. One, the air would get ...
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Phase diagram of $\text{He}^3$ at low temperatures

The $p(T)$ phase diagram of $\text{He}^3$ at low temperatures is given here: https://de.wikipedia.org/wiki/Pomerantschuk-Effekt#/media/File:Phasendiagramm_He3log.gif How can one physically explain ...
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Gas at absolute zero

According to Charles's Law, the volume of gas is proportional to temperate at constant pressure. So, the volume of a gas decreases as temperature decreases. Then, in theory, as the temperature ...
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How well do pressure measurements translate to temperatures?

At low temperatures we measured the changing pressure in a cryostat and converted these to temperatures using the function given by Donnelly (p1267; doi). But it seems that this is only accurate if ...
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Why does an AC current cause a resonator to vibrate?

This is an experiment I'm going to be doing, and I can't quite get my head around it. The experiment is performed at very low temperatures to investigate the properties of superfluids. There's a ...
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