Questions tagged [bose-einstein-condensate]

A Bose–Einstein condensate is a state of matter of a dilute gas of bosons cooled to temperatures very close to absolute zero. In this state, a large fraction of the bosons occupy the *lowest quantum state* so that macroscopic quantum phenomena are in evidence. Use for all related BEC processes.

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Partition function of weakly interacting Bose gas

In the Bogoliuobov theory of superfluidity, the hamiltonian of a system of weakly interacting bosons in second quantized notation is diagonalized with the following result: $$\hat H = H_0 \hat1 + \...
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Atom interferometry,gravity and inertia: What can it measure that light interferometry can't? [closed]

What previously unexplored effects in gravity and inertia can be examined with atom interferometry in ways that hasn't already been done through light interferometry? Can atom interferometry be used ...
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Difference between a Quadrupole-Ioffe-Configuration trap and crossed dipole trap?

I'm working on a project for my physics class which involves understanding traps such as MOT, QUIC and crossed dipole traps. I'm having a hard time finding resources to understand them starting at a ...
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Introductory condensed matter physics book [duplicate]

I need a book for general condensed matter physics, preferably at an undergraduate level, e.g. at Ashcroft and Mermin's level or below. Modern applications are preferred.
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Superconductivity and superfluidity in bosonic and fermionic condensates

Can bosonic and fermionic condensates explain superfluid and superconducting properties? Are they better than the theory of BCS and Landau? Edited: My question is based in this lecture pesentation ...
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Dipolar Bose-Einstein condensate

Is possible to study the dysprosium-BEC only using a mean-field approximation? I know the beyond mean-field brings new properties to BEC, but is it possible to use only the mean-field approximation?
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Compute fluctuation in particle number in ideal Bose Gas

Consider grand canonical partition function $Z = \prod_{k} \left(1-e^{-\beta(\varepsilon_k-\mu)}\right)^{-1}$ for an ideal Bose-gas in a trapping potential with energy levels $\varepsilon_k$ and ...
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What's the difference between laser light and incoherent classical light in terms of the path integral formalism?

So I believe I have the followings things straight: The electromagnetic field is described by the Lagrangian $\mathcal{L}=F_{\mu\nu}F^{\mu\nu}$. By writing down the Euler-Lagrange equations, or ...
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Can I achieve BEC with electrons only?

Suppose I traps some free electrons using magnetic field and cool them to subzero temperature, can I get a super-electron this way? and does it violate the exclusion principle?
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How is the BE condensate different from ordinary states of matter?

The Bose-Einstein (BE) condensate is said to be a new state of matter which is fundamentally different from solid. liquid or gas. What are some of these properties which separate it from ordinary ...
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Is Bose condensation experimentally achieved for a free Bose gas?

Bose-Einstein condensation is a phenomenon that theoretically happens for free Bose gases because Bose-Einstein distribution holds for free Bose gases. But in superconductors and superfluids, there ...
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Does phononic “Superconductivity” exist?

Can solids be cooled to a sufficiently low temperature such that sound can travel through them without acoustic impedance? It seems that if I had a solid in the shape of a torus, sitting in ambient ...
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Why do pairing and condensation occur simultaneously in superconductors?

Bose condensation in the weak-coupling limit (such as BCS superconductors) and the strong-coupling limit (like BECs of atoms) can be unified into a single framework by the BEC-BCS crossover. One key ...
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Grand canonical fluctiation catastrophe in Bose-Einstein condensate of polaritons?

Description of Bose-Einstein condensation (BEC) using grand canonical ensemble results in strongly fluctuating distribution $p(N_0)\sim e^{-N_0(\epsilon_0-\mu)/T}$ of a number of condensate particles $...
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What is the wavefunction of a Bose-Einstein condensate made of composite particles?

The textbook answer is that a problem involving bosons is described by a wavefunction $\Psi(R_1,...,R_n)$ which is completely symmetric, and if non-interacting particles Bose condense, the ...
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Solving many-body problems with a quantum microscope

https://physics.aps.org/synopsis-for/10.1103/PhysRevLett.118.240402 It is known that the Schrödinger equation can not be solved for many body system, but in this article cited above, the wave ...
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What is the relation between Bose Einstein Condensate of Higgs and the Higgs field?

I have been wondering the relation between Higgs BEC and Higgs field. During reheating of the universe, people always claim the energy density of inflaton drops down like massive particles without ...
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about BCS-BEC crossover

In BCS-BEC crossover, we will get two self-consistent equations about the gap $\Delta$ and the chemical potential $\mu$. But when I compute the particle density: $n=\beta^{-1}\sum_k tr(G\frac{\partial ...
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Why zero chemical potential does not allow the Bose-Einstein Condensation of Phonons?

Here I report the reasoning from which my question comes. According to: O.V. Misochko, Muneaki Hase, K. Ishioka, and M. Kitajima. Transient bose–einstein condensation of phonons. Physics Letters A, ...
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How to explain BEC of noninteracting boson in 2nd quantization? How to spontaneously break $U(1)$ symmetry of free boson?

Every textbook of statistical mechanics will derive the Bose-Einstein condensation(BEC) of free boson. I know how to derive in this way. It gives the heat capacity of free boson is $C\propto T^{3/2}$. ...
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BEC in two-level system [closed]

Let's take an energy level density function for a particle as $\rho(E)=const {V} {\delta(E-\varepsilon)}$, $V$ is a gas volume, $\delta(E-\varepsilon)$ - delta-function, $\varepsilon$ - energy level ...
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Degree of freedom of a BEC

I would like to know how many degrees of freedom an atomic gas has. What about the Bose-Einstein condensation from that gas?
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Is the 'way atoms spin' mentioned in the article “Physicists observe 'negative mass'” the same thing as quantum spin?

The BBC News article Physicists observe 'negative mass' talks about a recent observation of negative effective mass in a BEC gas; in its description of the experiment the article writes To create ...
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Negative mass, or just the 'appearance' of negative mass? What's the acid test?

Breaking news here claim researchers at Washington State University have created negative mass by the characteristic that if you push it, it accelerates in the opposite direction. The so called ...
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Are condensates of gravitational waves possible?

Bose-Einstein condensation has been observed in a multitude of physical systems (cold atoms, exciton-polaritons, magnons to name a few). Notably in 2010 a BEC of photons was experimentally detected. ...
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Exctitation spectrum of Bose-Einstein condensate

The Gross-Pitaevskii equation $$ i\hbar\frac{\partial\psi}{\partial t}=-\frac{\hbar^2\nabla^2}{2m}\psi+V\psi+U_0|\psi|^2\psi $$ ($V$ is the external potential, $U_0$ is the interaction constant) in ...
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Differential equation with nonlinear nonlocal interaction

I am studying literature on the nonlinear Schroedinger equation. More generally, I am wondering how to tackle an equation of motion such as $\bigl(i\partial_t-\Delta\bigr)\psi(\vec{x},t)+V(\vec{x},t)=...
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How can Bose-Einstein Condensate improve our understanding of Dark Matter and Dark Energy?

There was this news a few days ago about NASA attempting to create the Coldest Spot in the Universe1 aboard ISS, to study further the properties of Bose-Einstein Condensate. I can understand that at ...
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What is a Yang-Gaudin Bose gas?

I'm a mathematicians with interests in physics and mathematical physics. I have some kind of understanding of Quantum Groups and I know that Gaudin Models are related to them in a way that I don't ...
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Would cooling matter and antimatter to as close to Absolute Zero as possible allow them to coexist?

I was reading about Bose-Einstein condensates and how they affect matter and energy, and I wondered if "draining" that amount of energy from an atom of hydrogen and positronium would potentially allow ...
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Is a Gravastar more dense than a Neutron Star?

Given: A Neutron star is the collapsed core of a larger star; Models for Neutron stars suggest they are composed almost entirely of neutrons; And if: Bose-Einstein condensates are extremely dense ...
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What's the role of BEC in superfluidity?

I'm writing about superfluid $^4$He. I've seen in some places that the transition to superfluid is attributed to Bose-Einstein condensation, but then in others that this model needs a massive amount ...
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Symmetry breaking and Superfluid - Mott Insulator transition

I know my question is similar to what mentioned in this post: Symmetry breaking in Bose-Hubbard model. Yet, I don't find it clear. I've in mind a 1D Bose-Hubbard Hamiltonian. Moving from the Mott ...
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Inflation and the build up of an inflaton condensate

Recently I've been reading up a bit on inflation and the subsequent reheating of the early universe. What has left me a bit confused, however, is that in all of the notes/papers that I've read so far ...
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What is the advantage of making a BEC in space?

The NASA Cold Atom Laboratory, which I believe is slated to launch this year, has the goal of putting a Bose Einstein Condensate (BEC) apparatus on the ISS. What is the advantage of doing this? ...
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What are the limitations of Gross-Pitaevskij equation?

I'm a mathematician and I'm studying as an aside something about superfluids. If I understood correctly in some kind of superfluids as Bose-Einstein Condensate a wave in the fluid must satisfy the ...
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Why is the Higgs VEV called vacuum Higgs condensate?

In this Lubos says that Higgs VEV is also called vacuum Higgs condensate which the term used by Prof. Englert in this video. Since the Higgs field is bosonic, I wonder whether this terminology has ...
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Why do fermions not have a Bose-Einstein Condensate phase? [closed]

My misconception was that electrons were present in a BEC. However, how do fermions behave in low temperature and how does it differ from the behaviour of bosons?
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How do we actually measure the temperature of a BEC?

I guess quite some people here are familiar with Bose-Einstein condensates (BEC) and their properties. We know that the necessary temperature for condensation is given by $$ T_C \simeq 3.3125 \frac{\...
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Exact global phase of the Gross-Pitaevskii wavefunction

I will follow closely the book by Kaspar Sakmann chapter 3.2 about derivation of the time-dependent Gross-Pitaevskii equation. Starting from the time-dependent variational principle we arrive at the ...
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Does the Hong-ou-Mandel effect happen within a delay equal to the coherence time of the two photons?

I read that photon bunching happens for thermal light within the coherence time of the thermal light. That is, if the time for detection is greater than the coherence time of the thermal light, no ...
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In what elements has BEC been achieved?

I'm seeking to compile a list of all atomic (or otherwise) species with which Bose-Einstein condensation has been experimentally achieved. So far, I've collected photons (Klaers 2010) excitons (Dai ...
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Is Bose-Einstein condensate in the optical lattice a single mode condensate?

I recently read about BEC loaded into the optical lattice p.200 Looking at a condensate released from a lattice after a time of flight typically on the order of a few milliseconds amounts to ...
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Condition for Bose-Einstein Condensation

One way of calculating the critical temperature (or the critical number of particles) is (as seen in Statistical Mechanics, Pathria, p. 184) this: Starting with the equation: $\frac{N}{V} =\frac{1}{...
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Aether existance in alternate universe made of Bose-Einstein condensate

I came across an interesting question which was shown to me by my professor, it is as follows: Investigation of an alternative Universe: This Universe contains three spatial and one time ...
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Could a black hole be a Bose-Einstein condensate of gravitons?

Gravitons are bosons. As such they should obey the Bose-Einstein statistics at low temperature. And this means they should form a Bose-Einstein condensate at temperature close to absolute zero. ...
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Time of flight images of Bose-Hubbard model

on the website of Immanuel Bloch, you can find time of flight images of bosonic particles inside an optical lattice for different values of the depth of the lattice. (http://www.quantum.physik.uni-...
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How can helium be liquid at absolute zero, given the Third Law of Thermodynamics? [duplicate]

I learned recently that Helium is a liquid even at 0K. Doesn't that mean that it still have some entropy? If so, does it not violate the postulate of thermodynamics that states that entropy must go to ...
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Does spin affect the expression for a Bose-Einstein Condensate's critical temperature?

In an assignment, we were asked to find the critical temperature of a collection of Rubidium-87 atoms. The answer used an expression derived for spin-zero bosons in Schroeder's Thermal Physics (which ...
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Why do we use grand canonical ensemble for BEC description?

The system we consider has constant $N$, $V$ and $T$ (the number of particles, volume and temperature) This is just the thermodynamic variables for the canonical ensemble, why we use fugacity $z$ or ...