English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present a theoretical study of a four-electron four-quantum-dot systembased on molecular orbital methods, which hosts a pair of singlet-triplet spinqubits. We explicitly take into account of the admixture of electron wavefunctions in all dots, and have found that this mixing of wave functions hasconsequences on the energy spectrum, exchange interaction and the gatecrosstalk of the system. Specifically, we have found that when the twosinglet-triplet qubits are close enough, some of the states are no longerdominated by the computational basis states and the exchange interaction cannot simply be understood as the energy difference between the singlet andtriplet states. Using the Hund-Mulliken calculation of the Hubbard parameters,we characterize the effective exchange interaction of the system and have foundgood agreement with results calculated by taking energy differences whereapplicable. We have studied the two commonly conceived schemes coupling twoqubits, the exchange and capacitive coupling, and have found that when theinter-qubit distance is at certain intermediate values, the two kinds ofcoupling are comparable in strength, complicating analyses of the evolution ofthe two qubits. We also investigate the gate crosstalk in the system due to thequantum mechanical mixing of electron states and have found that while thiseffect is typically very weak, it should not be ignored if the spacing betweenthe qubits are similar to or less than the distance between the double dotsthat constitute the qubit.

Energy spectrum, exchange interaction and gate crosstalk in a pair of double-quantum-dot system: a molecular orbital calculation