(a) Model for an Aharonov-Bohm (AB) ring with an embedded quantum dot. A quantum dot with an energy level ε
0 is connected to two external leads by tunnel couplings, V
. Another arm of the AB ring (reference arm) and external leads are represented by a one-dimensional tight-binding model. The reference arm includes a tunnel barrier with transfer integral W. The magnetic flux Φ penetrating the ring is considered as an AB phase ϕ = 2π Φ/Φ0 with flux quantum Φ0 = h/e. (b) The density of states in the lead for the reduced model, ν(ε
) in Eq. (6). ν(ε
) oscillates with the period of ε
T, the Thouless energy for the ballistic systems. Its amplitude and phase depend on the AB phase ϕ.