What is Singlet: Definition and 63 Discussions

In quantum mechanics, a singlet state usually refers to a system in which all electrons are paired. The term 'singlet' originally meant a linked set of particles whose net angular momentum is zero, that is, whose overall spin quantum number



s
=
0


{\displaystyle s=0}
. As a result, there is only one spectral line of a singlet state. In contrast, a doublet state contains one unpaired electron and shows splitting of spectral lines into a doublet; and a triplet state has two unpaired electrons and shows threefold splitting of spectral lines.

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  1. I

    Why is the singlet configuration anti-symmetric?

    Obviously because there is a minus sign in |0 0> = 1/sqrt(2)*((up)(down)-(down)(up)) but I guess I am not completely sure why |0 0> can't equal 1/sqrt(2)*((up)(down)+(down)(up))... m still equals zero, and aren't we pretty much arbitrarily deciding that the spins are oppositely aligned in the...
  2. M

    Why is the eta meson's composition known as the singlet state?

    Why is the composition of eta prime meson known as the singlet state? See: http://en.wikipedia.org/wiki/Eta_meson Thanks
  3. J

    Singlet and Triplet Spin States

    In a system with two spin 1/2 particles , We now ask what are the allowed total spin states generated by adding the spins ${\bf S}= {\bf S}_1 + {\bf S}_2$ ,in fact, they are Singlet and Triplet Spin States \left( \begin{array}{ll} |1,1\rangle & =\uparrow\uparrow\\ |1,0\rangle &...
  4. A

    What is meant by the term gauge singlet ?

    What is meant by the term "gauge singlet"? Can anybody please explain what is meant by the term "gauge singlet"? To be more specific, I got the term in a discussion on wess-zumino lagrangian where the superpotential contains the term:a_i \phi_i . The author claims that in order the theory to...
  5. S

    Singlet state like |e>= |+> |-> - |-> |+>

    In a singlet state like |e>= |+> |-> - |-> |+> if we take the two particles far apart and measure the spin of the first particle S1 first, we get the answer +1 or -1 with the same probability. This means that if we perform many measurements of S1 over many equal states |e> we get...
  6. S

    Triplet vs. Singlet diatomic molecules: Why the energy difference?

    I've been doing some research on singlet-triplet molecular states, and one things I can't perfectly settle is a rigorous demonstration of why the triplet state is a higher energy than the singlet. One way I can qualitatively understand why the singlet state has lower energy is this: If the...
  7. P

    Baryon singlet representation for SU(3) flavour symmetry

    Hi there! As most people already might know, we can decompose the 27 dimensional representation for the baryons under SU(3) flavour symmetry as 27 = 10 + 8 + 8 + 1. I can find a lot of information about the particles that lie in the decuplet and in the octet, but nothing about which particle...
  8. Q

    Is the singlet state just a special case of mixture?

    If the answer is no, why? Is it possible to show that, given the state spaces we have for individual particles, the singlet state is not a mixture of product states? If yes, how?
  9. C

    [PhD Qualifier] Spin singlet state

    Homework Statement Consider a system made up of two spin 1/2 particles. Initially the system is prepared in a spin singlet state with total spin S_{total}=0. We'll define the spin components of one particle as (s_{1x},s_{1y},s_{1z}) and of the other as (s_{2x},s_{2y},s_{2z}) a. If no...
  10. A

    Singlet- triplet splitting energy of He what does it mean?

    [SOLVED] singlet- triplet splitting energy of He! what does it mean? Hello every body! i need to plot the singlet- triplet splitting energy of He for the ^{1}S and ^{3}S states corresponding to the configurations (1s,ns), n=1 to 7, and then explain why the plot is like that! please help...
  11. G

    Atom can give rise to singlet, doublet, triplet, and quartet states?

    How do you know if an atom can give rise to singlet, doublet, triplet, and quartet states? I'm having a hard time understanding this
  12. S

    Singlet - triplet splitting in helium

    We're asked to make a rough order of magnitude estimate of this splitting. I know that it is caused by the coulomb interaction between the electrons. Therefore I estimated the potential between them as being V = (e^2)/(4*Pi*epsilon*a) where a =a0/2 a0 is the bohr radius I've assumed that...
  13. K

    How do i get the singlet state?

    In all my books the singlet and triplet state of a two-electron system seem to be postulated as obvious. The problem is that the sollutions somehow aren't obvious to me at all. I can see i can derive the s=1 states by applying a lowering operator to |s=1,m=1> =|++> But it doesn't help me in my...
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