Recent content by physengineer

Thank you, Cthugha! Yes, I want it for a detector. I can cool it down to 4.2K too. Single photon sensitivity is also required. I need the maximum absorption for the thinnest possible film, say a few nano meter. Spectral resolution is not an issue as long as either telecom freqs i.e. 1310 or 1550...

Hi ThereIam, No, not cell phones. Just detecting few photons of 1550nm or 1310nm photons at the end of an optical fiber. Thanks

Thank you, f95toli! In fact, I am interested in telecom wavelengths: 1550 nm or 1310 nm. Since the number of photons are very limited we need to absorb as much as we can.

Hi all, I am looking for the best material for IR (infra red) absorption, preferably something that I can make it into a thin film; any material that would work from semiconductors, metals to more exotic materials like graphene or... I appreciate your help. Thank you

Thanks, Sambristol! In fact my question on "kinetic capacitance" comes from studying "quantum phase slip". I understand it as a combination of coefficients with the dimension of capacitance in the "effective action" introduced by Golubev and Zaikin; however, I was hoping to get some physical...

What is "kinetic capacitance" in superconductors or in solid state in general? Hi, I would appreciate it if anyone could explain to me what "kinetic capacitance" is, particularly in the context of superconductors or solids. I understand "kinetic inductance" which comes from the kinetic...

Hello, I would appreciate it if anyone could help me with this problem: can there be any instantonic contribution to the following generic two-points function? \left \langle \varphi(x) \varphi(y) \right\rangle= \int D\varphi D A \varphi(x) \varphi(y) \exp \left( -S_E...

Hello, I need to measure the complex-optical conductivity of some materials. The problem is that I can only measure the imaginary part of the complex conductivity only for limited wavelengths between 1030 nm and 2300 nm. From Kramers-Kronig relations, we know that the real and imaginary...

Hello, Conductivity \sigma (\omega, k) in Fourier space is defined by J(\omega, k)= \sigma (\omega, k) A(\omega, k) In most cases the local limit of k\rightarrow 0 is a good approximation particulalry in type I superconductors and HTC superconductors. I am interested in cases...

I am not sure if I understood your question exactly and my reply may sound trivial. Anyway, when you have a symmetry there are invariants associated with each of those symmetries (Noether's Theorem). In other words some quantities will be conserved during, let's say, a collision experiment like...

Could anyone please, explain the connection between the Free Energy and the Action? I know the definitions of each but not sure about the connection. I read somewhere that the free energy is the same as the action when calculated "on-shell". What does this "on-shell" thing mean in this...

Thanks, DrDu! I appreciate your help.

Thanks a lot, DrDU! I am just not sure if I understood exactly what you meant for (2) My effective action is complex and non local but fortunately remains quadratic in terms of A and \psi or combination of these two. Therefore I can technically integrate over both A and \psi in the path...

Hi, In calculating the conductivity from the Kubo method j_{\mu}=\int dx' K_{\mu \nu} (x,x') A^{\nu}(x') in literature ( e.g. in Condensed Matter Field Theory by Altland and Simons) you find that K_{\mu \nu}(x,x')= Z^{-1} \frac{\delta^2}{\delta A_{\mu}(x) \delta A_{nu}(x')}...

EM response function of the "Phase Action" of a BCS superconductor Hello, I am looking for a paper in which people calculated the EM response of phase action of A BCS SC. In the book "Condensed Matter Field Theory" by Altland and Simons, on page 393 they mention such a thing in the discussion...