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Inconsistency in scattering length of spherical well potential

I'm trying to understand the scattering length of the spherical well potential $$V(r)=\begin{cases}-V_0&r<r_0\\ 0&r>r_0\end{cases}$$ The $V_0>0$ (attractive) case is fairly well ...
Zeyang Li's user avatar
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37 views

Flux pinning upon a ultracold vapor of neutral atoms

Suppose I have a mixture of two different atoms A and B, both with an even but different number of electrons which fully fill both of their outermost shells. The two are different elements. Now, ...
Young Jun Lee's user avatar
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1 answer
68 views

Ultracold magnetic traps for uranium enrichment

As noted by Mr. Gremlin in this post: How is it possible to accelerate a neutron? Crudely paraphrasing, subatomic particles with non-zero magnetic dipole moments interact with magnetic fields to give ...
Young Jun Lee's user avatar
6 votes
4 answers
1k views

Gas or liquid? a Bose-Einstein condensate

It is often said that a Bose-Einstein condensate of cold atoms is a gas. But because of Andrews' discovery of the critical temperature, we know that a gas and a liquid is not fundamentally different. ...
poisson's user avatar
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15 votes
2 answers
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Why are Alkali atoms used in many Cold Atom experiments?

It seems that alkali atoms are often used in cold atom experiments. The first BEC was formed with alkali atoms, and many modern experiments used Alkalis. What is special about having a single electron ...
Zonova's user avatar
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43 views

$s$-wave scattering approximation of the two-body interaction

In quantum gases, one usually approximates the two-body interaction $V(\boldsymbol{r})$ with a s-wave delta potential $$V_{\text{pseudo}}(\boldsymbol{r}) = \frac{4\pi \hbar^2 a}{m} \delta (\boldsymbol{...
Hao's user avatar
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1 vote
1 answer
61 views

Creating entangled states via Rydberg blockade

I was watching a talk by Prof. Mikhail Lukin and I have a silly question. In the talk, he discussed that a typical procedure for generating a Bell pair consists of using the Rydberg blockade on two ...
Cicero 's user avatar
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3 votes
1 answer
167 views

Molecular orbital notation

I'm reading about papers about atom-ion interaction. There are some states as showned above. The notations of the states look like molecular orbital since $\Sigma$ and $\Pi$ is usually used in orbital ...
Han Bao's user avatar
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2 votes
1 answer
34 views

Cold atoms in optical tweezers

Can someone recommend a good reference for learning about cold atoms in/with optical tweezers? I am interested in both the theoretical and experimental aspects. On my own, I couldn't find any ...
Cicero 's user avatar
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0 answers
32 views

Why is a singlet state potential greater than triplet state potential in the Feshbach resonance experiment?

I googled the Feshbach resonance in the Wikipedia and I have some problems. In German Wikipedia, they consider Li-6 molecule as an example. For these two different spin configurations(singlet and ...
Hsu Bill's user avatar
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1 answer
44 views

Atom Interferometer Contrast

I have made a simulation of a Raman beam based atom interferometer in a Mach-Zehnder configuration. In this way, the electronic state of the atom changes as well as the momentum when diffraction by ...
jamie1989's user avatar
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How a does a RF magnetic field interact with trapped atoms in evaporative cooling?

In the paper “Evaporative Cooling of Trapped Atoms,” [Advances in Atomic Molecular And Optical Physics 37, 181–236 (1986)] by Wolfgang Ketterle and N. J. Van Druten, they claimed the matrix element ...
Hsu Bill's user avatar
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1 vote
0 answers
30 views

How does a RF-induced evaporative cooling remove hotter atoms in the dressed state picture?

I am stuck in the problem of evaporative cooling in a magnetic trap. $\textbf{Introduction}$ In the magnetic trap, I assumed the trap is an Ioffe-Pritchard trap. So the Majorona loss is prohibited. ...
Hsu Bill's user avatar
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0 answers
16 views

Why is the Lamor frequency much faster than trapping frequency required in the magnetic trap?

I study the magnetic trapping recently. I met a problem. I consider the original quadruple magnetic trap. In the original quadruple magnetic trap, the magnetic vanishes at the center. The Majorana ...
Hsu Bill's user avatar
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1 vote
0 answers
22 views

Why doesn't optical pumping work when there is no external field to cause Zeeman splitting

I discovered a strange phenomenon in an experiment related to optic pumping and magnetic resonance. In this experiment, I optically pump electrons in Rb85 to the $5S_{1/2}, F=2, m_{F}=+2$ state and in ...
Bababeluma's user avatar
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0 answers
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Why is there a linear relationship between the output frequency of a laser diode and the voltage applied to it?

I'm using a tunable laser diode in an undergraduate Rb SAS (saturated absorption spectroscopy) experiment. The product I'm using is the Toptica DLC DL pro, links down below (not an ad). The frequency ...
Bababeluma's user avatar
3 votes
0 answers
38 views

How to select a proper term to proceed a mean-field approximation?

Recently I read some literature about how people use the mean-field approximation to solve a particular physical problem. However, I saw people using it in a different way when they dealt with ...
JensenPang's user avatar
1 vote
1 answer
226 views

BCS-BEC crossover: relation between scattering length and bare interaction

I am studying the BCS-BEC crossover in atomic Fermi gases from this reference https://arxiv.org/pdf/1402.5171.pdf , but I am having hard times understanding some of the details. In particular I can't ...
Matteo's user avatar
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3 votes
0 answers
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Physical effects of large detuning conditions in adiabatically eliminates cavity mode? [closed]

A simple question: how to adiabatically eliminates cavity mode in this thesis: here is arXiv/journal link of it page2, just above equation (2): such that we can adiabatically eliminate the cavity ...
ffz's user avatar
  • 73
3 votes
1 answer
420 views

Why does Majorana spin flipping occur?

Currently, I am reading the Nobel Lecture in Physics of 1997 by William D. Phillips. The lecture itself can be downloaded from this website: https://www.nobelprize.org/prizes/physics/1997/phillips/...
Asaf Toprakçı's user avatar
-5 votes
2 answers
84 views

How can I keep my just bought dozen of popsicles cold as long as possible? [closed]

It's hot and I bought a dozen of pear popsicles. I discovered the fridge with freezer is dead. How can I keep them cold as long as possible so I don't have to eat them all at once?
MatterGauge's user avatar
1 vote
1 answer
48 views

Examining isotope shift in ions vs neutral atoms - why use ions?

I'm currently deep-diving isotope shift (IS) spectroscopy literature. I've come across several papers that look at the isotope shifts of charged ions, and I want to try and understand why researchers ...
compp's user avatar
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1 answer
76 views

Why does Cadmium have a large natural linewidth? And why does this make Zeeman shifting more difficult?

I am reading through this paper and am unable to find information on the following statement: "Since Cd has a large linewidth, high magnetic field gradients are required to shift the Zeeman ...
compp's user avatar
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-1 votes
2 answers
492 views

Question about the energy levels of Rubidium atom - how to understand this energy level diagram?

But today when I try to read some papers working with Alkaline atom, I couldn't figure out how they plot the Rubidium energy level. From my undergraduate study, I thought the diagram of Rubidium atom ...
Zizheng Yang's user avatar
0 votes
1 answer
823 views

Phase space density for Bose-Einstein condensation

A figure of merit for Bose-Einstein condensation is the phase space density which can be defined as $$\rho=n\lambda_T^3,$$ where $n$ is the number density of atoms and $\lambda_T$ the thermal de ...
jamie1989's user avatar
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2 votes
1 answer
161 views

Confusion over Feynman’s description of the Wu experiment for parity violation

In his lecture on symmetry in physical law, Feynman said: Using a very strong magnet at a very low temperature, it turns out that a certain isotope of cobalt, which disintegrates by emitting an ...
P0W8J6's user avatar
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0 votes
2 answers
39 views

How is two-level optical transition in a spin 1 system affected by the third level?

Suppose you have a spin-1 system. Let us resonantly drive the transition between any 2 levels (say 0 1 transition). How would the the presence of the third level (-1) state affect this transition? We ...
alpha_prime's user avatar
3 votes
1 answer
137 views

How are the wavelengths calculated to hold and combine atoms in optical trapping?

I am reading this article of scientists who combined individual atoms using optical tweezers. One optical tweezer used a 700 nm-wavelength light to hold the sodium atom while the other optical ...
Qubit's user avatar
  • 431
1 vote
1 answer
30 views

What system has a spectral series in the radio spectrum?

As an electron energy level has an emission level depending upon the excitation, is it possible for a system such as a Rydberg atom to have emissions in the low side of the frequency range?
Evamentality's user avatar
1 vote
1 answer
53 views

Hypersonic Bose–Einstein condensate

In this nature paper, a BEC is accelerated around a smooth ring-shaped waveguide within a vacuum chamber at UHV. The BEC reaches speeds up to 16 times the condensate's speed of sound. What is the ...
jamie1989's user avatar
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0 votes
1 answer
238 views

Doppler cooling limit and the Heisenberg uncertainty limit

In laser cooling, the forces arise because of the discreet momentum exchange between the atoms and the laser field. This exchange of momentum also constitutes a heating mechanism. Relating the heating ...
jamie1989's user avatar
  • 1,816
1 vote
2 answers
129 views

Is it possible to laser cool without using spatially-varying magnetic fields and above zero degrees?

As the title says, is it possible to laser cool without generating a weak quadrupolar magnetic field? Also, if I wasn't trying to achieve extremely low temperatures is it possible to use laser cooling ...
G Gr's user avatar
  • 247
6 votes
1 answer
592 views

BCS pairing and BEC pair between Fermions

In many lecture notes, it points out We can tune the scattering length, using Feshbach resonance, to realize crossover from BCS to BEC in degenerate Fermi gases. When the scattering length is ...
xiang sun's user avatar
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0 answers
41 views

Is there a laser in which based on Ytterbium

I understand that Ytterbium can emit a photon with a relatively high and very accurate frequency (narrow band of frequency). I also know that Ytterbium is being used to verify frequency in atomic ...
Ofer's user avatar
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1 vote
1 answer
109 views

How is three-dimensional laser cooling possible?

I am a bit confused about laser cooling an atom in all three dimensions. I think I have understood the one-dimensional case: The atom absorbs doppler-shifted laser light and the momentum in this ...
Christian's user avatar
  • 393
1 vote
2 answers
1k views

Can we make cold without producing heat?

It seems to me you can put a heater on without expelling cold to the other room like an air conditioner and freezer would. Is there a way to reduce heat locally by slowing down molecules for example? ...
Winston's user avatar
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1 vote
1 answer
145 views

Two different to do Bogobliubov transformation but sees to be contradictary

When try to do bogoliubov transformation on a weak-interaction cold atoms with uniform velocity $\vec{v}$, I used two different approaches, giving two different results. The Hamiltonian is $$\hat{H}=\...
xiang sun's user avatar
  • 776
2 votes
2 answers
337 views

What wavelengths are used practically in optical trapping?

I am currently working on my Master thesis in a cold atom research group, and have irritatingly found -- or rather not found -- that no book or paper seems to explicitly mention what wavelengths are ...
John Doe's user avatar
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1 vote
2 answers
202 views

What is the longest wavelength ever measured for a Black Body?

As said in the title, I am curious about the reported measurements for cooled black bodies. Any source is welcome. I am neither interested in any thought experiment nor in the well-established law of ...
HolgerFiedler's user avatar
1 vote
1 answer
565 views

Any introductory books/articles on ultra-cold atoms?

I am currently only a high school student wanting to pursue physics at the tertiary level of education. Are there any books people can recommend on ultra-cold atoms? I would like to discover more ...
0 votes
1 answer
64 views

Using an electric/magnetic field to cool particles

I was just thinking that temperature and the motion of atoms are connected. Hence, I was wondering why we can’t just use a magnetic or electric field to hold atoms more or less in place, lowering ...
dl19's user avatar
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3 votes
1 answer
134 views

What is a good definition for what this article talking about when it refers to "Universal Physics"?

I was puzzled when I read "Precise measurements find a crack in universal physics by Ingrid Fadelli" (Phys.org, Jan. 15, 2020). The article has some vague statements in the opening paragraphs about "...
Jacob C.'s user avatar
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0 votes
1 answer
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Transitions within magnetic sub levels: evaporative cooling to Bose Einstein Condensation

Consider a Ioffe-Pritchard trap geometry. Evaporative cooling works by decreasing the trap depth to remove atoms which are more energetic than average; this leads to cooling. This is done by using ...
Physics99's user avatar
0 votes
1 answer
65 views

What is the classical counterpart of ultra-cold atoms?

I'm studying quantum chaos in ultra-cold atoms. However, quantum chaos denotes the quantum mechanics of classically chaotic systems and it is not clear to me what is the classical counterpart of ...
J.delaCruz's user avatar
2 votes
0 answers
25 views

Does the size, and distance between, expanding ultracold gas clouds depend on the populations in each cloud?

Say you had some $^{87}$Rb atoms at a few kelvin and you knew that the atoms were distributed among the magnetic sub-levels of a hyperfine manifold. You want to know the relative population of each by ...
Tech's user avatar
  • 120
13 votes
1 answer
2k views

Why is the density of a BEC so low?

I've just begun reading C. Pethick and H. Smith's textbook "Bose-Einstein condensation in dilute gases" (Cam. Uni. Press). In the Introduction, they contrast the density of atoms at the centre of a ...
dBozwerf's user avatar
  • 133
-2 votes
2 answers
455 views

How are atoms formes by electromagnetic waves that a specific frequency? [closed]

I came up something like this- Every piece of matter has a resonancefrequency or series of frequenciesbecause all matter is made up of atoms. Atoms are formed by electromagnetic waves that have a ...
Arifa Akhtar's user avatar
0 votes
1 answer
210 views

Is it BEC-BCS crossover the natural framework to explain superconductivity from ultracold atoms?

I know that superfluidity and superconductivity have very distinct characteristics and have specific theories. However, it seems that in ultra-cold atomic gases these phenomena can be understood by a ...
Dinesh Shankar's user avatar
-1 votes
1 answer
272 views

speed of freezing vs. moving [closed]

An idea came to my mind and like to discuss it. We know that out there in the space the absolute zero (aka. -273 C) is almost reached where all the particles and atoms would freeze up and stop giving ...
wisdom's user avatar
  • 111
4 votes
1 answer
187 views

In AMO experiments, how do cold alkali metal atoms remain gaseous?

My focus is on condensed matter physics, so I've never really explored this question although it always seemed curious to me. My "immediate reaction" intuition would dictate that cold metal atoms ...
BGreen's user avatar
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