Questions tagged [low-temperature-physics]

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What happens to Capacitors at extreme temperatures and pressures?

In my University physics class [first year engineering student] I learned that "for a capacitor in a vacuum, capacitance $C$ depends only on the shapes, dimensions, and separations of the ...
William Banquier's user avatar
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Techniques to measure/picture very low (cryo) temperatures [closed]

I am looking for an experimental technique to measure/create a temperature map of a small object (few mm diameter), like in terms of IR camera. However, all IR-cameras I encountered measured ...
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How do "traditional" and Nagaoka magnetism differ in their mechanism

I see that Nagaoka magnetism is a low-temperature quantum effect from "minimizing" the energy of the system, but that explanation, while erudite, doesn't really explore any specifics - ...
user121330's user avatar
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Questions about CCD sensors and low temperatures?

The dynamic range of a CCD sensor increases at low temp, they say. What does this mean, and why does it happen? Near saturation a CCD sensor begins to exhibit non-linear characteristics. Is this in ...
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How high pressure, high temperature liquid refrigerant exiting a Thermostatic Expansion Valve (TXV) turns into low pressure, low temperature liquid?

In a refrigerator or heat pump, how does high pressure, high temperature liquid refrigerant exiting a Thermostatic Expansion Valve (TXV) turn into low pressure, low temperature liquid? Is this a ...
Geremia's user avatar
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How does adding heat cause helium-3 to freeze? [duplicate]

According to here at 3MPa helium-3 actually goes from liquid to solid at 0.1 kelvin, this is the complete opposite of how normal materials behave, how is this possible?
blademan9999's user avatar
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2 answers
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What is the lower limit for experimentally measuring $T_c$ of superconductors?

I'm pretty new to this topic, but find it interesting, so please bear with me. Since superconductors with $T_c \approx 4.2\text{K}$ have been measured, I wonder, is it possible to have superconductors ...
vanilla1's user avatar
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1 answer
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Joule experiment in the low temperature regime

It is said that to prove mechanical energy can convert to heat energy, Joule measured the temperature increase of water after a free fall. He did his experiment at some waterfall. Because of the high ...
poisson's user avatar
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1 answer
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Understanding the Magneto-optical trap

I am reading about this apparatus at Wikipedia: https://en.wikipedia.org/wiki/Magneto-optical_trap And there is the following sentence which I don't understand: "As atoms travel away from the ...
imbAF's user avatar
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2 votes
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Why is zero entropy possible for a solid at absolute zero temperature?

The third law of thermodynamics states that the entropy of a perfect homogeneous solid is zero at absolute zero temperature. The reason to ask for "perfect and homogeneous" is that such a ...
KlausK's user avatar
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What is the temperature of the residual gas in a dilution refrigerator?

In a dilution refrigerator, the inner vacuum can is cooled by the mixing chamber to a base temperature of a few millikelvin. This experimental volume is kept under ultra high vacuum with typical ...
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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 – ...
Mamoun Ghazali's user avatar
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2 answers
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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?
eeqesri's user avatar
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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 ...
Arc's user avatar
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Is superconductance restricted to an extremely low temperature? Or can it be effectively replicated using some other technique? [closed]

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 ...
Vinyasi's user avatar
-1 votes
2 answers
329 views

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?
Solidification's user avatar
27 votes
3 answers
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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 ...
Vishwa Mithra Tatta's user avatar
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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^{\...
Neutralino's user avatar
2 votes
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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 ...
rob's user avatar
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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 ...
Martin Vesely's user avatar
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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 ...
Tofi's user avatar
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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 ...
Cristi B's user avatar
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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}^\...
Albus Black's user avatar
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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....
SG8's user avatar
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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 ...
Sarah's user avatar
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1 vote
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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 ...
Solidification's user avatar
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2 answers
768 views

What happens to the electrons mobility when metals get cooled down?

I know conductivity increases, but what happens to the electrons on the inside?
maria davinsky's user avatar
2 votes
0 answers
262 views

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 ...
Boa_Constrictor's user avatar
1 vote
1 answer
80 views

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]...
Henning's user avatar
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3 votes
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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-...
Vivek's user avatar
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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?
SkipX's user avatar
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1 vote
1 answer
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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 \...
Alex Goldstein's user avatar
1 vote
0 answers
248 views

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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3 answers
1k views

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?
Rhea's user avatar
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2 answers
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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 ...
Derek Seabrooke's user avatar
2 votes
1 answer
105 views

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 ...
tom894's user avatar
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0 answers
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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 ...
Ignacio's user avatar
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2 votes
2 answers
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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 ...
Mathieu Krisztian's user avatar
0 votes
1 answer
69 views

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 ...
Nikhil Murali's user avatar
1 vote
1 answer
349 views

Specific capacity of a diatomic molecule at low temperatures

My question is: Why at low temperatures does a diatomic molecule result in the same specific heat capacity as a monoatomic at a constant volume? My understanding is that at very high temperature ...
james2018's user avatar
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2 votes
1 answer
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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 ...
Andrew Strever's user avatar
4 votes
2 answers
10k views

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 ...
Anon's user avatar
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4 votes
2 answers
1k views

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, $PV= nRT$?
Tooba's user avatar
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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 ...
user6760's user avatar
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1 vote
2 answers
476 views

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 ...
Theoretical's user avatar
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3 answers
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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 ?...
Cornelis's user avatar
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1 answer
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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 ...
slaaidenn's user avatar
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2 votes
1 answer
855 views

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 ...
user avatar
1 vote
1 answer
130 views

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?
yalis's user avatar
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1 vote
1 answer
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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 ...
untreated_paramediensis_karnik's user avatar