shot noise in mesoscopic conductors - Low Temperature Laboratory
shot noise in mesoscopic conductors - Low Temperature Laboratory
shot noise in mesoscopic conductors - Low Temperature Laboratory
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144 Ya.M. Blanter, M. Bu( ttiker / Physics Reports 336 (2000) 1}166<br />
may be shown that for the bulk "ll<strong>in</strong>g factor "1/(2m#1), m3Z (Laughl<strong>in</strong> states), the <strong>in</strong>teraction<br />
parameter g takes the same value g"1/(2m#1). The di!erence with the ord<strong>in</strong>ary Lutt<strong>in</strong>ger<br />
liquid is that the FQHE edge states are chiral: the motion along a certa<strong>in</strong> edge is only possible <strong>in</strong><br />
one direction. Thus, if we imag<strong>in</strong>e a FQHE strip, the electrons along the upper edge move, say, to<br />
the right, and the electrons along the lower edge move to the left. For the transport properties we<br />
discuss this plays no role, and expressions (262) and (263) rema<strong>in</strong> valid.<br />
In particular, for the FQHE case the quasiparticles with the charge e may be identi"ed with the<br />
Laughl<strong>in</strong> quasiparticles. The dist<strong>in</strong>ction between the strong and weak tunnel<strong>in</strong>g we described<br />
above also gets a clear <strong>in</strong>terpretation (Fig. 37), which is <strong>in</strong> this form due to Chamon, Freed and<br />
Wen [313]. Indeed, consider a FQHE strip with a barrier. If the tunnel<strong>in</strong>g is strong (Fig. 37a), the<br />
edge states go through the barrier. The backscatter<strong>in</strong>g corresponds then to the charge transfer from<br />
the upper edge state to the lower one, and this happens via tunnel<strong>in</strong>g between the edge states <strong>in</strong>side<br />
the FQHE strip. Thus, <strong>in</strong> this case, there are Laughl<strong>in</strong> quasiparticles which tunnel. In pr<strong>in</strong>ciple, the<br />
electrons may also be backscattered, but such events have a very low probability (see below). In the<br />
opposite regime of weak tunnel<strong>in</strong>g, the strip splits <strong>in</strong>to two isolated droplets (Fig. 37b). Now<br />
the tunnel<strong>in</strong>g through the barrier is aga<strong>in</strong> the tunnel<strong>in</strong>g between two edge states, but it only may<br />
happen outside the FQHE state, where the quasiparticles do not exist. Thus, <strong>in</strong> this case, one has<br />
tunnel<strong>in</strong>g of real electrons.<br />
7.3.1. Theory of dc <strong>shot</strong> <strong>noise</strong><br />
Shot <strong>noise</strong> <strong>in</strong> Lutt<strong>in</strong>ger liquids was <strong>in</strong>vestigated by Kane and Fisher [314] us<strong>in</strong>g the bosonization<br />
technique. The conclusion is that for an ideal <strong>in</strong>"nite one-dimensional system there is no<br />
<strong>shot</strong> <strong>noise</strong>. Shot <strong>noise</strong> appears once the barrier is <strong>in</strong>serted. For the strong tunnel<strong>in</strong>g regime the<br />
<strong>shot</strong> <strong>noise</strong> is<br />
S"2ge((ge/2)