Local Control of Supercurrent Density in Epitaxial Planar Josephson Junctions

Elfeky, Bassel Heiba; Lotfizadeh, Neda; Schiela, William F.; Strickland, William; Dartiailh, Matthieu; Sardashti, Kasra; Hatefipour, Mehdi; Yu, Peng; Pankratova, Natalia; Lee, Hanho; Manucharyan, Vladimir; Shabani, Javad

doi:10.1021/acs.nanolett.1c02771

Cited by 25 publications

(10 citation statements)

References 36 publications

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“…Such gate-controlled superconducting response strongly supports our proposal of manipulating MBS with mini gates, when the topological superconductivity is achieved with B x and a phase bias, ϕ . This demonstration of the mini-gate control, first established in our work, was later extended to experiments with even a larger number of mini gates 45 .…”

Section: Resultssupporting

confidence: 64%

Fusion of Majorana bound states with mini-gate control in two-dimensional systems

et al. 2022

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A hallmark of topological superconductivity is the non-Abelian statistics of Majorana bound states (MBS), its chargeless zero-energy emergent quasiparticles. The resulting fractionalization of a single electron, stored nonlocally as a two spatially-separated MBS, provides a powerful platform for implementing fault-tolerant topological quantum computing. However, despite intensive efforts, experimental support for MBS remains indirect and does not probe their non-Abelian statistics. Here we propose how to overcome this obstacle in mini-gate controlled planar Josephson junctions (JJs) and demonstrate non-Abelian statistics through MBS fusion, detected by charge sensing using a quantum point contact, based on dynamical simulations. The feasibility of preparing, manipulating, and fusing MBS in two-dimensional (2D) systems is supported in our experiments which demonstrate the gate control of topological transition and superconducting properties with five mini gates in InAs/Al-based JJs. While we focus on this well-established platform, where the topological superconductivity was already experimentally detected, our proposal to identify elusive non-Abelian statistics motivates also further MBS studies in other gate-controlled 2D systems.

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Section: Resultssupporting

confidence: 64%

Fusion of Majorana bound states with mini-gate control in two-dimensional systems

et al. 2022

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“…In the long-array limit, a giant-spin model yielded a quantum phase transition as function of flux offset between protected and unprotected regimes. The construction of interferometer array protected qubits can be realized using existing semiconductor-superconductor hybrid materials based on semiconductor nanowires [19] or twodimensional heterostructures [28,45,46]. where ñ and ñg are vectors that contain the Cooper pair number operators and the offset charges of the N +1 superconducting islands, and φ is the vector of phase operators.…”

Section: Discussionmentioning

confidence: 99%

Protected hybrid superconducting qubit in an array of gate-tunable Josephson interferometers

Schrade¹,

Marcus²,

Gyenis³

2021

Preprint

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We propose a protected qubit based on a modular array of superconducting islands connected by semiconductor Josephson interferometers. The individual interferometers realize effective cos 2φ elements that exchange 'pairs of Cooper pairs' between the superconducting islands when gate-tuned into balance and frustrated by a half flux quantum. If a large capacitor shunts the ends of the array, the circuit forms a protected qubit because its degenerate ground states are robust to offset charge and magnetic field fluctuations for a sizable window around zero offset charge and half flux quantum. This protection window broadens upon increasing the number of interferometers if the individual elements are balanced. We use an effective spin model to describe the system and show that a quantum phase transition point sets the critical flux value at which protection is destroyed.

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“…For each junction leg in our device, a negative gate voltage can act to concentrate J c (x i ) near the mesa edges, where the gating efficiency is weaker. This is due to formation of an electron accumulation layer at the mesa edge which shows weak gate coupling, and is a consequence of the band bending effect in InAs [36][37][38]. The other peak in the J c (x i ) forms near the common central region as the gates do not cover the junction legs entirely.…”

Section: Tuning Of Diode Polarity and Efficiency By Electrostatic Gatingmentioning

confidence: 99%

Superconducting Diode Effect in a Three-terminal Josephson Device

Gupta¹,

Graziano²,

Pendharkar³

et al. 2022

Preprint

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The phenomenon of non-reciprocal critical current in a Josephson device, termed Josephson diode effect, has garnered much recent interest. It is typically attributed to spin-orbit interaction and time reversal symmetry breaking in these systems. Here we report observation of the Josephson diode effect in a three-terminal Josephson device based upon InAs quantum well two-dimensional electron gas proximitized by epitaxial aluminum. We demonstrate that the diode efficiency can be tuned by a small out-of-plane magnetic field and electrostatic gating. We show that the diode effect in this device is a consequence of artificial realization of a current-phase relation that is non-2π-periodic.These Josephson devices may serve as gate tunable building blocks in designing topologically protected qubits. Furthermore, we show that the diode effect is an inherent property of multiterminal Josephson devices. This establishes an immediately scalable approach by which potential applications of the Josephson diode effect can be realized, which is agnostic to the underlying material platform.

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Local Control of Supercurrent Density in Epitaxial Planar Josephson Junctions

Cited by 25 publications

References 36 publications

Fusion of Majorana bound states with mini-gate control in two-dimensional systems

Fusion of Majorana bound states with mini-gate control in two-dimensional systems

Protected hybrid superconducting qubit in an array of gate-tunable Josephson interferometers

Superconducting Diode Effect in a Three-terminal Josephson Device

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