# What is Bose einstein: Definition and 38 Discussions

In condensed matter physics, a Bose–Einstein condensate (BEC) is a state of matter (also called the fifth state of matter) which is typically formed when a gas of bosons at low densities is cooled to temperatures very close to absolute zero (−273.15 °C or −459.67 °F). Under such conditions, a large fraction of bosons occupy the lowest quantum state, at which point microscopic quantum mechanical phenomena, particularly wavefunction interference, become apparent macroscopically. A BEC is formed by cooling a gas of extremely low density (about one-hundred-thousandth (1/100,000) the density of normal air) to ultra-low temperatures.
This state was first predicted, generally, in 1924–1925 by Albert Einstein following and crediting a pioneering paper by Satyendra Nath Bose on the new field now known as quantum statistics.

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1. ### Second moment of occupation number for bosons

I tried to show this equality by explicitly determining what $$\overline{(\Delta \eta)^2}$$ is, but I got a totally different answer for some reason, here is my attempt to solve it, what did I miss?
2. ### Temperature of Bose Einstein Condensation

For finding n, I believe that directly applying the above formula gives the results. But I am confused whether I have to put the value of given temperature T = 100K or the actual temperature Tc for Rb-87 at which BE Condensation occurs (i.e. 100 nK, which I got from a quick Google search)? Or do...
3. ### I Bose Einstein Condensate For Oxygen 16 and Oxygen 18

I am interested in whether or not Bose Einstein condensates have been realized for spin zero stable oxygen isotopes and if so, the maximum density achieved for these condensates. I understand that the quantum spins of oxygen 16 and oxygen 18 are both zero so such condensates would seem to be...
4. ### Question in Bose-Einstein statistics

iam not getting why in bose statistics the number of ways to arrange ni particles in gi degenerate states is = (gi+ni-1) ? and why do we divide by ni factorial , and gi factorial .
5. ### Particle Bose Einstein Condensate Original Paper

Anyone has the original paper on the Bose-Einstein condensate? Searched on Google without any success.
6. ### B Practical use of Bose-Einstein condensate?

I'm not a physicist nor an academic, however, the world around me fascinates me. I was watching YouTube and came across an explanation of Bose Einstein condensate, and thought with less space between atoms that would potentially be a better target for creating new elements. So my question is...
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### B Bose–Einstein condensate and Hadron Collider

Just out of curiosity I was wondering what would happen if a Bose-Einstein condensate were placed in a Hadron Collider. Is it even possible?
8. ### I Testing Quantum Gravity paper Bose Einstein helium superfluid

Testing Quantum Gravity Johan Hansson, Stephane Francois (Submitted on 19 Oct 2017) The search for a theory of quantum gravity is the most fundamental problem in all of theoretical physics, but there are as yet no experimental results at all to guide this endeavor. What seems to be needed is a...
9. ### Simulating 1D time-independent Bose Einstein Condensation

Hello! I'm trying to simulate a one dimensional time independent BEC, I hope this is the right place to ask for help. First of all, here's my code in Python. import sys import numpy as np import matplotlib.pyplot as plt if len(sys.argv) == 1: niter = 100 elif len(sys.argv) == 2: niter...
10. ### Bose Condensation in 2D

Hi, I was given the following question: Show that Bose condensation does not occur in 2D. Hint: The integral you will get when you write the formula for N is doable in elementary functions. You should find that that N ∝ ln(1 − e βµ). I do indeed find that N ∝ ln(1/(1 − e βµ)) ∝ ln(1 − e βµ)...
11. ### A Fugacity of Ideal Bose Gas: Exploring the Connection to Chemical Potential

We know that the average occupation number cannot be negative for all systems and chemical potential must be negative in Ideal Bose Gas. This fact leads us to arrive a conclusion for fugacity which is related by chemical potential, as I quoted below: The restriction of the fugacity to the...
12. ### Criteria for boson and Bose Einstein Condensate

The answer is given as (a). I want to know the reason. It is a boson. Why can't it form a Bose-Einstein condensate?
13. ### Energy of electron-hole pairs in 3D space

Dear All: I'm trying to use fluctuation dissipation theorem to describe spontaneous photon emission process by electron-hole recombination in semiconductor material. I notice that all the references using such a method considers the dipole's degree of freedom separately, for example in x, y, z...
14. ### Arithmetic mean Fermi Dirac & Bose Einstein

Hi everybody, I was doing one asignment form class, I was tasked to prove that in one system, the arimetic mean of FD and BE distributions is equal to MB's distribution for undishtingable particles. After doing the numbers I found out that it actually was, but I don't know why this happens, can...
15. ### Bose Einstein condensation

Homework Statement Explain the conditions under which Bose-Einstein condensation occurs and show this happens for density ##\rho \equiv N/V > \rho_C(T)##, where $$\rho_C(T) = A(kT)^{3/2} \int_0^{\infty} \frac{x^{1/2}}{ e^x − 1} dx .$$ Suppose the energy of the particles on the lattice is now...
16. ### Quantum Bose Einstein effects on a macro scale?

If say a hundred or more objects, at a human scale, are connected by a string, and they can be made to synchronize in an oscillation, could that be considered a bose einstein condensate?
17. ### Bose Einstein condensation in 2D finite space

It can be easily proved that Bose Einstein condensation can be got in infinite 2D. But what about finite 2D with extreme large "Volume" L^2 ?
18. ### Bose Einstein Condensation

Hi, my course just provided an introduction to Bose-Einstein Condensation. I was told that this phenomenon occurs when the temperature of Bosons go under a certain critical temperature T_{c} > 0K. At absolute zero, all the Bosons go into the condensed phase. However, at temperatures...
19. ### Oscillation of a Bose Einstein condensate in an harmonic trap

Homework Statement We were asked to try to make a theoretical description of the following phenomenon: Imagine a 2D Bose Einstein condensate in equilibrium in an harmonical trap with frequency ω. Suddenly the trap is shifted over a distance a along the x-axis. The condensate is no longer...
20. ### Bose Einstein condensates and GR?

If time is constantly moving the direction of increasing entropy and quantum systems are time symetric then how do macropscopic entanlged systems such as bose-einstein condensates relate temporally to themselves and larger systems of which they might be subsets? Because BECs are large enough to...
21. ### Why is z=1 below Tc in Bose Einstein condensation?

Hi. For a Bose gas, my textbook states that below the critical temperature, which is given by n(λth)3/(2S+1)=2.612, the fugacity z=eβμ≈1. Why is this? The most basic explanation possible would be ideal, as I only need the rough idea. Thanks! :smile:
22. ### Sound in Bose Einstein Condensates.

Hello there I love physics, so I normally read a lot of physics books. I am fascinated about BECs and their possible applications. I've read about BECs and BEC vacuum theory, also that is possible to create black holes in superfluids (as BEC) using sound (sonic black holes). As far as I know...
23. ### Gross-Pitaevskii equation in Bose Einstein condensates

Hello, I was hoping someone might be able to give a approachable explination of the Gross-Pitaevskii equation. All the sources I've been able to find seem to concentrate on the derivation, and I don't have the physics background to follow. From what I understand, however, is that the GP...
24. ### Zero Point Energy and Bose Einstein Condensates

They say ZPE is the energy of the system at 0 K due to vibrations and even though the Schroedinger equation gives us the ground state minimum energy of the system (lets say by DFT/HF/QMC whatever), this energy is a little higher than that. My first question is, because I have learned that...
25. ### Bose Einstein condensate/ atom laser

Dear, I am reading a paper on Bose Einstein condensate and an atom laser. I have two questions which are bothering me for a time. - When you are going to make do all the atoms start with the same the Broglie wavelenghts or do they start with different wavelenghts due to different...
26. ### What makes Bose Einstein condensates so effective at slowing/stopping light?

I was just wondering what properties of bose einstein condensates allows them to slow/stop light so well. cant find much on the internet about it, tho i am probably looking in the wrong places, so if anyone could give me links that would be useful Thanks Also, this isn't homework, I'm...
27. ### Prediciting Bose Einstein statistics

Homework Statement First, let's derive the predictions for He-4 atoms at very low temps given the MB distr. Homework Equations The Attempt at a Solution Given the MB distr., if the ground state of the system is assumed to be at zero energy, then the ratio of occupation numbers...
28. ### Bose Einstein condensate on subatomic particles

Hello My name is Peter I know that so far some couple of people manage to make a Bose -Einstein condensate from a metal and from hydrogen, I would like to ask your opinion about what do you believe will happen if not the full atom will be brought to the Bose Einstein condensate state or...
29. ### Bose Einstein condensation

show that in the thermodynamic limit the bose gas condensate does not contribute to pressure for ideal bose gas in volume V with N particles.and physically explain. how to get it start?and what will b its physicsl explanation? kindly reply soooooooooooon
30. ### Photons and Bose Einstein statistics

Can a photon gas undergo a Bose Einstein condensation ?
31. ### Bose Einstein Condensation

Hi i tried in the other section with no luck. Let me try here if there are anyone here that can help me. the question is: Suppose one catches in 5000-Na atoms in a spherical-shaped cloud with diameter of 2mm. And suppose that the atoms are uniformly distributed in that sphere. At what...
32. ### Bose Einstein fermi dirac

Hi everyone I need the historical articles that bose and fermi integrals were defined for the first time. Can anyone help me?
33. ### Discussing Bose Einstein Condensate: Questions & Answers

Is this the right place to discuss Bose Einstein condensate.
34. ### Solition Wave in Bose Einstein Condensate

goooooovy man http://www.youtube.com/watch?v=QxbutNmaL-s&NR=1 addendum: any body know any other soliton waves in nature that are this aeshetically impressive?
35. ### Bose Einstein condensate

A few questions about BEC: A) When these bosons condensate, many particles fill the ground state. I read from textbooks that this would imply that they occupy the same position. -1- experiments are done with Rb atoms, which consist of protons, neutrons and electrons. Wouldn't the electrons...
36. ### Bose Einstein condensation and subatomic-speed

If we cool down a small sample of atoms and see bose-einstein condensation, and so the speed of the atoms is slowed down dramatically, what can we say about the speed of the sub-atomic particles (quarks etc..), do we know how their speed is being changed? regards, marcel
37. ### Bose Einstein Condensate

Does Bose Einsteine Condesate violate the Pauli Exclusion Principle?
38. ### Bose Einstein condensate can be made to attract

this subject,amoung others facinate me, does anyone have an insight as to what is happening here?