Local tuning of the order parameter in superconducting weak links: A zero-inductance nanodevice

Abstract

Controlling both the amplitude and phase of the quantum order parameter in nanostructures is important for next-generation information and communication technologies.The long-range coherence of attractive electrons in superconductors render these materials as a nearly ideal platform for such applications. To-date, control over has remained limited to the macroscopic scale, either by adjusting untunable materials properties, such as film thickness, stoichiometry and homogeneity or by tuning external magnetic fields. Yet, although local tuning of is desired, the lack of electric resistance in superconductors, which may be advantageous for some technologies hinders convenient voltage-bias tuning. Likewise, challenges related to nanoscale fabrication of superconductors encumber local tunability of .Here, we demonstrate local tunability of , obtained by patterning with a single lithography step a Nb nano superconducting quantum interference device (nano-SQUID) that is biased at its nano bridges. Our design helped us reveal also unusual electric characteristics-effective zero inductance, which is promising for quantum technologies and nanoscale magnetic sensing.Finally, we accompanied our experimental results by a semi-classical model, which not only is extending the applicability of our devices, but is also useful for describing planar nano-SQUIDs in general.

Targeted modifications of monolithic multiterminal superconducting weak-links

“…In this context, a three-terminal device, so-called yTron, has been proposed as a sensor and readout of current-flow in a superconductor 3 whereas tunable superconducting weak links have been realized by injecting a normal current into the junction. [4][5][6][7][8][9][10][11][12][13][14] More recently, substantial theoretical [15][16][17][18] and experimental [19][20][21][22][23] efforts have been devoted to the investigation of multiterminal Josephson junctions, in part fueled by the possibility of developing topological Andreev bands in systems composed by multiple superconducting leads coupled through a central normal scattering region. Typically these devices require involved fabrication procedures (overlay lithography, shadow evaporation, multilayers, etc.)…”

“…In this context, a three-terminal device, so-called yTron, has been proposed as a sensor and readout of current-flow in a superconductor 3 whereas tunable superconducting weak links have been realized by injecting a normal current into the junction. 4–14…”

Local tunability in a multi-port SQUID by an injection current

“…However, from a * Author to whom any correspondence should be addressed. scientific-engineering perspective, the ability to control both the supercurrent, phase difference, and parameters locally is essential for next-generation functional quantum circuit integration [10][11][12][13]. Very recently, the local tunability of supercurrent has been demonstrated by introducing new materials and applying an electrostatic field, e.g.…”

Nonvolatile voltage-tunable ferroelectric-superconducting quantum interference memory devices

“…Thus, superconducting quantum devices lack the convenient gating platform that semiconducting transistors have. There has been therefore a continuous effort to introduce tunability to superconductive quantum devices, 9 including by ionic liquid 10,11 , as well as by voltage-tunable −SQUIDs. 12 A prominent example is integration of ferromagnetic components.…”