Two-photon absorption by a quantum dot pair

Tunneling induced absorption with competing Nonlinearities

“…1(b))36. The cascade-type biexciton system has already been examined by pump-probe17 and two-photon absorption experments30 and proposed for studying entanglement dynamics37. Similar artificial structures have also been used for tunneling induced transparency and related applications38394041.…”

“…The main difference between EIT and TIT is that EIT usually requires an external-field excitation and induced coherence, while TIT originates from tunneling induced coherence which is decided by the structure of the QDs. The interference mechanism2122, pulse propagation2324, and Kerr nonlinearity252627 in TIT have been extensively studied for applications in solid state qubits and quantum electrodynamics28; however, few have studied the TIA and related nonlinear optical properties despite the potential applications of TIA in solid-state quantum devices and as a classical analog of EIA29 or its role in two photon-absorption30 and photon-assisted absorption3132.…”

Self‐Assembled InAs/GaAs Coupled Quantum Dots for Photonic Quantum Technologies

“…The resulting energy level structure, including the unoccupied crystal ground state, is shown in Figure b. While the biexciton hole configuration has several spin‐dependent recombination pathways, the singlet state can be selectively prepared by two‐photon excitation . With the system initially prepared in the spin singlet state, relaxation occurs through successive emission of two photons with opposite polarization in the absence of spin‐flip transitions.…”

Entanglement dynamics of molecular exciton states in coupled quantum dots

“…The singlet spin state can be spectrally selected near a biexciton tunneling resonance, with triplet states excluded from the spin-conserving tunnel coupling, or by utilizing two-photon absorption, due to the selection rules of simultaneous transitions. 40 We consider the case of pulsed excitation, which allows for on-demand preparation of the molecular biexciton state and subsequent emission of a single entangled photon pair. For two-laser driving, one must further specify the relative timing of the two pulses: they may be applied sequentially, or concurrently.…”

“…Pulsed excitation of the molecular biexciton has not been examined experimentally, though continuous-wave excitation has been demonstrated. 40 Photon emission events can be described within the CQD and photon subspaces using transition operators σ1H/V,D/I (σ 2H/V,D/I ) and photon creation operators â † H/V , which act on the system to produce the first (second) H/V -polarized photon by direct/indirect recombination of the biexciton (exciton) state (see Table I for details). Assuming that the system has been prepared in the molecular biexciton spin singlet state |Ψ 0 = |iXX, S and that recombination occurs via the indirect exciton pathway without nonradiative transi-tions, the first recombination produces the state…”