Half-integer Shapiro steps in highly transmissive InSb nanoflag Josephson junctions

Iorio, Andrea; Crippa, A.; Turini, Bianca; Salimian, S.; Carrega, Matteo; Chirolli, Luca; Zannier, Valentina; Sorba, L.; Strambini, Elia; Giazotto, Francesco; Heun, S.

doi:10.1103/physrevresearch.5.033015

Cited by 5 publications

(3 citation statements)

References 95 publications

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“…In fact, for a standard sinusoidal CPR under microwave irradiation, the current-voltage characteristics develop voltage steps when , the so-called Shapiro steps, where s = 0, 1, 2, … and f ac is the external applied frequency. On the contrary, if the CPR becomes , signaling tunneling of pairs of Cooper pairs, steps at half-integer values also appear, i.e., s = 0, 0.5, 1, … 47 – 49 . In our case, we expect the ratio between the second and first harmonic to be maximized when the SQUID is balanced and , see Fig.…”

Section: Resultsmentioning

confidence: 99%

Parity-conserving Cooper-pair transport and ideal superconducting diode in planar germanium

Valentini,

Sagi,

Baghumyan

et al. 2024

Nat Commun

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Superconductor/semiconductor hybrid devices have attracted increasing interest in the past years. Superconducting electronics aims to complement semiconductor technology, while hybrid architectures are at the forefront of new ideas such as topological superconductivity and protected qubits. In this work, we engineer the induced superconductivity in two-dimensional germanium hole gas by varying the distance between the quantum well and the aluminum. We demonstrate a hard superconducting gap and realize an electrically and flux tunable superconducting diode using a superconducting quantum interference device (SQUID). This allows to tune the current phase relation (CPR), to a regime where single Cooper pair tunneling is suppressed, creating a $$\sin \left(2\varphi \right)$$ sin 2 φ CPR. Shapiro experiments complement this interpretation and the microwave drive allows to create a diode with ≈ 100% efficiency. The reported results open up the path towards integration of spin qubit devices, microwave resonators and (protected) superconducting qubits on the same silicon technology compatible platform.

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Section: Resultsmentioning

confidence: 99%

Parity-conserving Cooper-pair transport and ideal superconducting diode in planar germanium

Valentini,

Sagi,

Baghumyan

et al. 2024

Nat Commun

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“…These features are different from that of half-integer steps in ferromagnetic junctions, whose height exhibits weak correlation with temperature, [11] but are similar to that of Nb-InSb-Nb ballistic nanowire Josephson junction. [39] The relationship between the steps' height and RF radiation power has also been researched. Here, I-V curves of junction 1 under various microwave powers at magnetic fields of 27 Oe and 31.5 Oe are shown in Figs.…”

Section: Resultsmentioning

confidence: 99%

Half-integer Shapiro steps in MgB₂ focused He ion beam Josephson junctions

Yin 殷,

Cai 蔡,

Xu 徐

et al. 2024

Chinese Phys. B

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Half-integer microwave induced steps (Shapiro steps) have been observed in many different Josephson Junction systems which have attracted a lot of intention because they signify the deviation of current phase relation (CPR) and uncover many unconventional physical properties. In this article, we first report the discovery of half-integer Shapiro steps in MgB2 Focused He Ion Beam (He-FIB) Josephson Junctions. The half-integer steps’ dependence on microwave frequency, temperature, microwave power and magnetic field is also analysed. We find that the existence of half-integer steps can be controlled by magnetic field periodically which is similar with that of high temperature superconductors (HTS) grain boundary junctions and the similarity of the microstructures between gain boundary junctions and He-FIB junctions is discussed. As a consequence, we mainly attribute the physical origin of half-integer steps in MgB2 He-FIB junctions to the model that a He-FIB junction is analogous to a parallel junctions’ array. Our results show that He-FIB technology is a promising platform for researching CPR in junctions made of different superconductors.

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“…Importantly, spin–orbit interaction, a key parameter in forefront areas of physics, can be tuned by a vertical electric field applied through InAs and InSb nanosheets with the dual-gate architecture. , One of the prerequisite conditions to study the diverse physics in semiconductor-superconductor hybrid systems is the induced superconductivity in the semiconductors by the proximity effect. Recently, proximity induced superconductivity has been realized in InSb nanosheet Josephson junctions. ,− Free-standing InAs nanosheets, on the other hand, appear as contestant materials with the similar intriguing properties as InSb nanosheets. ,, More importantly, Al, as a widely used superconductor, could be epitaxially grown onto InAs nanostructures , with a relatively stable superconductor-semiconductor interface, while epitaxial growth of Al on InSb nanostructures with high quality, stable interface is still challenging. , Considering the advantages of InAs-based superconductor-semiconductor hybrids, proximity induced superconductivity in free-standing InAs nanosheets deserves to be demonstrated, which has not been reported yet.…”

mentioning

confidence: 99%

Supercurrent, Multiple Andreev Reflections and Shapiro Steps in InAs Nanosheet Josephson Junctions

Yan

Pan

et al. 2023

Nano Lett.

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We report an experimental study of proximity induced superconductivity in planar Josephson junction devices made from freestanding InAs nanosheets. The nanosheets are grown by molecular beam epitaxy, and the Josephson junction devices are fabricated by directly contacting the nanosheets with superconductor Al electrodes. The fabricated devices are explored by low-temperature carrier transport measurements. The measurements show that the devices exhibit a gatetunable supercurrent, multiple Andreev reflections, and a good quality superconductor-semiconductor interface. The superconducting characteristics of the Josephson junctions are investigated at different magnetic fields and temperatures and are analyzed based on the Bardeen−Cooper− Schrieffer (BCS) theory. The measurements of the ac Josephson effect are also conducted under microwave radiations with different radiation powers and frequencies, and integer Shapiro steps are observed. Our work demonstrates that InAs nanosheet based hybrid devices are desired systems for investigating the forefront of physics, such as two-dimensional topological superconductivity.

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Half-integer Shapiro steps in highly transmissive InSb nanoflag Josephson junctions

Cited by 5 publications

References 95 publications

Parity-conserving Cooper-pair transport and ideal superconducting diode in planar germanium

Parity-conserving Cooper-pair transport and ideal superconducting diode in planar germanium

Half-integer Shapiro steps in MgB₂ focused He ion beam Josephson junctions

Supercurrent, Multiple Andreev Reflections and Shapiro Steps in InAs Nanosheet Josephson Junctions

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Half-integer Shapiro steps in highly transmissive InSb nanoflag Josephson junctions

Cited by 5 publications

References 95 publications

Parity-conserving Cooper-pair transport and ideal superconducting diode in planar germanium

Parity-conserving Cooper-pair transport and ideal superconducting diode in planar germanium

Half-integer Shapiro steps in MgB2 focused He ion beam Josephson junctions

Supercurrent, Multiple Andreev Reflections and Shapiro Steps in InAs Nanosheet Josephson Junctions

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Product

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Half-integer Shapiro steps in MgB₂ focused He ion beam Josephson junctions