Coherent population trapping by dark state formation in a carbon nanotube quantum dot

Abstract

Illumination of atoms by resonant lasers can pump electrons into a coherent superposition of hyperfine levels which can no longer absorb the light. Such superposition is known as a dark state, because fluorescent light emission is then suppressed. Here we report an all-electric analogue of this destructive interference effect in a carbon nanotube quantum dot. The dark states are a coherent superposition of valley (angular momentum) states which are decoupled from either the drain or the source leads. Their emergence is visible in asymmetric current−voltage characteristics, with missing current steps and current suppression which depend on the polarity of the applied source-drain bias. Our results demonstrate coherent-population trapping by all-electric means in an artificial atom.

Correlation-Centric Network (CCN) representation for microbial co-occurrence patterns: new insights for microbial ecology

“…According to (Equation 4 ), a species with a large degree yields more nodes in the corresponding CCNs, and this species led to the expansion of differences in four phases. Hence, we speculated that most of the important constituent species of gut microbiome could be preserved during the changing phases, and the changes of species correlations played a role in adapting to the changes in the environment, as reported previously ( 40 , 41 ). This result indicates that the species–species correlations possess a greater discriminative power than species for distinguishing samples, which is consistent with previous studies ( 24 ).…”

Pseudospin resonances reveal synthetic spin-orbit interaction

“…A crucial role in this phenomenon is played by the exchange magnetic field [2] generated by virtual electronic fluctuations between the dot and the leads, i.e., the Lamb shift correction to the dot Hamiltonian. Orbitally degenerate states support as well interference if combined with couplings to the leads which mix the tunneling channels [12,13], as has been demonstrated for semiconductor wires [14,15], QD molecules [16][17][18][19][20][21][22], single-molecule junctions [20,23,24], and suspended carbon nanotubes (CNTs) [25]. Moreover, exchange magnetic fields are able to alter the symmetry of Kondo states [26].…”

“…A concrete example of pseudospin description is given in [25]. The angular momentum states of the CNT provide a two-level system with symmetry-protected degeneracy.…”

Multilevel coherences in quantum dots

“…Using the flavor framework, we will be able to explain NDC and current blockades due to coherence effects (similar as reported in Refs. [32][33][34][35][36][37][38][39][40][41][42][43]) in terms of flavor blockade and its lifting by flavor rotation.…”