Controlled Dephasing of an Electron Interferometer with a Path Detector at Equilibrium

Abstract

Controlled dephasing of electrons, via 'which path' detection, involves, in general, coupling a coherent system to a current driven noise source. However, here, we present a case in which a nearly isolated electron puddle at thermal equilibrium strongly affects the coherence of a nearby electronic interferometer. Moreover, for certain average electron occupations of the puddle, the interferometer exhibits complete dephasing. This robust phenomenon stems from the Friedel Sum Rule, which relates a system's occupation with its scattering phases. The interferometer opens a peeping window into physics of the isolated electron puddle, which cannot be accessed otherwise.

Initial states of qubit–environment models leading to conserved quantities

“…One can name at least one case, commonly referred to as dephasing [2], where the energy exchange between two systems is absent during the entire evolution regardless of the initial conditions. In open quantum system theory, where it is often assumed that the second subsystem is much larger than the first one, this phenomenon is also known as the pure decoherence [3].…”

High-temperature Aharonov-Bohm effect in transport through a single-channel quantum ring

“…One can check that Eq. (26) is nothing but the thermodynamic average = over the zero mode energies (20). We see that the function is sharply peaked at the points t = 2πm/αΔ with integer m ≥ 0 (see = λ -iαΔf j ± (λ 2 + iαΔΓf j ) 1/2 and λ = (iαΔ -Γ)/2.…”

“…For a thermodynamic ensemble of the "isolated baths," the conductance should be averaged over the Gibbs distribution of the zero mode energies [48], , (20) where N 0 is controlled by the chemical potential and N = N + + Nis the total number of electrons in the ring. Equation (20) describes, quite generally, electro statics of a 1D ring.…”

“…Equation (20) describes, quite generally, electro statics of a 1D ring. The resulting conductance as a function of φ shows PCB oscillations with a period α/2 and a Gaussian envelope whose width w T = α(T/Δ) 1/2 is entirely determined by the statistical weights of dif ferent values of J.…”

“…This effect is one of the most beautiful manifestations of the wave nature of electrons. The key physical issue-the sensitivity of the phase of an electronic wavefunction to a magnetic flux-enables the design of quantum AB interferometers [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] that can be tuned by an external magnetic field.…”