H2020Индивидуална стипендия2019–2021

SpinScreen · Screening of an electron spin by an epitaxial superconducting island in a semiconductor nanowire

„Хоризонт 2020“ — Действия „Мария Склодовска-Кюри“

Период: 2019-09-01 → 2021-08-31
Финансиране от ЕС: 207 312 €
Участници: 1
Схема: MSCA-IF-EF-ST

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Накратко на български

Взаимодействието между единични електрони и двойки електрони в хибридни полупроводник-свръхпроводник материали се изследва при екстремно ниски температури. Това помага за разработването на по-стабилни кубити, които да намалят грешките при работата на бъдещите квантови компютри.

Този кратък обзор е генериран от изкуствен интелект

Кратко обяснение, генерирано от езиков модел по текста на CORDIS. Оригиналът е по-долу.

Резултати накратко

Screening of an electron spin by an epitaxial superconducting island in a semiconductor nanowire

Quantum computers can potentially tackle some problems faster than conventional computers but suffer from operational errors in their fundamental unit of processing, the qubit. A new type of qubit immune to error is needed, and it may be based on hybrid semiconductor-superconductor materials. This sort of hybrid can be miniaturized into a tiny island, the heart of the future error-free qubit. A key idea is to use a quantum dot to read the state of this qubit. Both quantum dot and island can be conceived as small boxes of electrons. While the quantum dot is a box for single electrons, the island is a box for pairs of electrons, so-called Cooper pairs. When put together, the two boxes spill their electrons to each other, which provides a way of detecting the qubit state on the island. A superconductor, however, interacts with a quantum dot in an additional way. The superconductor can donate an unpaired electron to bond with a single electron in the quantum dot if the spins of the two electrons point in opposite directions. The total spin is zero, so it is said to be screened. Until now, the way this interaction proceeded (if it proceeded at all) when the superconductor is miniaturized was unknown. In SpinScreen, experiments were performed at -273 degrees Celsius on hybrid semiconductor-superconductor materials shaped into these boxes of electrons, with the main objective of elucidating their interactions.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз

Цел на проекта

Europe’s leadership in quantum technologies can only be sustained by fundamental research. A challenge in this field is to choose the physical platform for qubits, the units of a quantum computer. Semiconductor nanowires coupled to superconductors offer a potential solution as a platform for a new type of qubit, which has the unique advantage of being inherently protected from decoherence.The physical ingredients of this qubit are Majorana modes. A common device geometry used to investigate transport through these modes is a superconducting island coupled to a nanowire.However, at this stage little is known about the interactions of islands with quantum dots, which are themselves commonplace near charge depletion. Whereas the interaction of a single dot strongly coupled to a superconductor lead at fixed potential is known to lead to anti-ferromagnetic screening by quasiparticles in the superconductor, the interaction of the dot with an isolated superconductor remains to be explored. If this gap in the knowledge is filled, we could learn to distinguish between subgap states related to screening of the dot, and those involving the island/nanowire hybrid. Crucially, only the latter ones are related to Majorana modes.At QDev, I will investigate screening by an epitaxial superconducting Al island of a single quantum dot defined in an InAs nanowire. To do this, I will tune the coupling between the island and the dot with a gate voltage and obtain the quantum phase diagram.While most of Majorana research is understandably focused on how to make a qubit, I will tackle three more fundamental questions, which will serve this purpose in the long run and go substantially beyond the state of the art. 1) How does a single quasiparticle in the island screen a spin? 2) How does screening occur when the island cannot accept quasiparticles? 3) Can novel non-Fermi liquid physics emerge when adding a superconducting lead to the dot-island system?

Оригинален текст от CORDIS (на английски).

Участници

KOBENHAVNS UNIVERSITET · KOBENHAVNКоординаторДания