Quantum Metrology Electrical Triangle

Informazioni relative al progetto

QMET

ID dell’accordo di sovvenzione: 101029189

DOI

10.3030/101029189

Progetto chiuso

Data della firma CE 11 Marzo 2021

Data di avvio 1 Luglio 2021

Data di completamento 30 Giugno 2023

Finanziato da

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Costo totale

€ 184 707,84

Contributo UE

€ 184 707,84

Coordinato da

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
France

Periodic Reporting for period 1 - QMET (Quantum Metrology Electrical Triangle)

Periodo di rendicontazione: 2021-07-01 al 2023-06-30

Sintesi del contesto e degli obiettivi generali del progetto

Decades after the definition of quantum voltage and resistance standards, a quantum current standard is missing. This last one turned out to be more challenging than the previous two, and nowadays the current unit is basically given by extremely precise current sources. A standard definition of the Ampere can be obtained exploiting the dual counterpart of the Josephson effect, namely voltage Bloch Oscillations. A way to measure them consists in embedding a largely non-linear Josephson junction in a high impedance environment, irradiate it with a microwave pump to observe discrete DC current steps, the dual of Shapiro steps. The QMET action tackles this objective. Such result would provide a leap in quantum metrology and paves the way to the redefinition of the ampere using only fundamental constants.

Lavoro eseguito dall’inizio del progetto fino alla fine del periodo coperto dalla relazione e principali risultati finora ottenuti

We made the preliminary simulations which results were used to design and choose the circuit’s parameters, then developed the recipe and fabricated the actual devices. We designed and benchmarked the measurement circuitry in a dilution refrigerator, and programmed a dedicated data acquisition and analysis setup. We performed measurements and analysed the data comparing them with further simulations. In our device we observed dual Shapiro steps emerging from the synchronisation of an external microwave tone with the Cooper pair dynamics, which was the aim of this action. The results were discussed among the authors, and with expert colleagues like D. Haviland, T. Duty, and M. Devoret. We wrote a manuscript concerning the results. This was achieved in the timespan of one year. The scientific importance of the result was endorsed by several colleagues, and the paper received enthusiastic reviews, saying that this work “[...] represents a genuine breakthrough for the worldwide research in condensed matter physics”, and that “they do not rely only on transport measurements [...] but they use microwave spectroscopy using a circuit QED architecture. This represents a formidable and unique tool [...]”.
The following experiments were devoted to the study of the device, which shows a complicated but interesting physics, which are going to be published soon.

Progressi oltre lo stato dell’arte e potenziale impatto previsto (incluso l’impatto socioeconomico e le implicazioni sociali più ampie del progetto fino ad ora)

The experimental evidence of dual Shapiro steps, paves the way to the closure of the quantum metrology electrical triangle, it is the new state-of-the-art, and it unlocked a new field of study in superconducting circuits.

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