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arXiv:2610.29865

From Traveling Waves to Synthetic Gauge Fields: A Field-Free Route to Superconducting Diode Effect

Latu Kalita, Koustav Roy, Bilal Tanatar, Saurabh Basu

cond-mat.mes-hallcond-mat.otherquant-phSubmitted Oct 21, 2026• Announced Oct 22, 2026
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Abstract

The superconducting diode effect requires the forward and reverse bias currents to differ, a scenario achieved via inversion and time-reversal symmetries broken together. The latter, and the more crucial one, is inevitably achieved by a magnetic field. Here, we show that a spatio-temporally driven chemical potential of the form, $μ_j(t)=μ+V\cos(ωt+\kd j)$, achieves both at once. Applied to a helical Shiba chain, the drive transmutes a traveling Peierls phase via generating an odd-in-momentum term, equivalent to an imaginary next-nearest-neighbour Haldane-like hopping in real space. Remarkably, the protocol is spin-blind, which renders the time-reversal breaking via a synthetic gauge flux rather than an effective Zeeman field. The rectification is odd in the drive wavevector, with exact zeros at $\kd=nπ$ and an analytical optimum at $\kd=2π/3$. It is however, even in the exchange coupling, $J$ and persists even at $J=0$. Furthermore, the rectification scales inversely with the pair-breaking gap, yielding approximately $50\%$ rectification in the topological phase and $10\%$ in the trivial phase. Symmetry breaking is thus drive-controlled, allowing it to be switched on, tuned, and reversed without an external magnetic field.

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The superconducting diode effect requires the forward and reverse bias currents to differ, a scenario achieved via inversion and time-reversal symmetries broken together. The latter, and the more crucial one, is inevitably achieved by a magnetic field. Here, we show that a spatio-temporally driven chemical potential of the form, μj(t)=μ+Vcos⁡(ωt+\kdj)μ_j(t)=μ+V\cos(ωt+\kd j)μj​(t)=μ+Vcos(ωt+\kdj), achieves both at once. Applied to a helical Shiba chain, the drive transmutes a traveling Peierls phase via generating an odd-in-momentum term, equivalent to an imaginary next-nearest-neighbour Haldane-like hopping in real space. Remarkably, the protocol is spin-blind, which renders the time-reversal breaking via a synthetic gauge flux rather than an effective Zeeman field. The rectification is odd in the drive wavevector, with exact zeros at \kd=nπ\kd=nπ\kd=nπ and an analytical optimum at \kd=2π/3\kd=2π/3\kd=2π/3. It is however, even in the exchange coupling, JJJ and persists even at J=0J=0J=0. Furthermore, the rectification scales inversely with the pair-breaking gap, yielding approximately 50%50\%50% rectification in the topological phase and 10%10\%10% in the trivial phase. Symmetry breaking is thus drive-controlled, allowing it to be switched on, tuned, and reversed without an external magnetic field.
Diode is one of the basic electronic components. It has a nonreciprocal current response, associated with a broken space/time reversal symmetry. Here we demonstrate prototypes of superconducting diodes operational at zero magnetic field. They are based on conventional niobium planar Josephson junctions, in which space/time symmetry is broken by a combination of self-field effect from nonuniform bias and stray fields from a trapped Abrikosov vortex. We demonstrate that nonreciprocity of critical current in such diodes can reach an order of magnitude and rectification efficiency can exceed 70%. Furthermore, we can easily change the diode polarity and switch nonreciprocity on/off by changing the bias configuration and by trapping/removing of a vortex. This facilitates a memory functionality. We argue that such a diode-with-memory can be used for a future generation of in-memory superconducting computers.
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We demonstrate a practical, field-free superconducting diode based on conventional Nb thin-film technology by integrating an intrinsic superconducting phase battery with an asymmetric DC superconducting quantum interference device. Unlike other approaches that require external magnetic fields or gate voltages to break time-reversal symmetry, our design achieves nonreciprocal supercurrents with on-chip phase bias, making it highly suitable for practical applications. The critical operational parameters, including the backward breakdown voltage and reverse resistance, are well defined by the Nb film gap voltage (∼2.8 mV) and the sub-gap resistance of the un-shunted Nb/Al–AlOx/Nb Josephson junctions. The resulting diode exhibits a forward supercurrent of 168 μA at 4.2 K, with a diode efficiency reaching 40%, a comprehensive performance exceeding prior field-free superconducting diodes. To validate its practicality, we fabricate and characterize a superconducting full-wave rectifier consisting of four such diodes. The demonstration of this rectifier highlights its potential as a DC source for superconducting digital circuits, paving the way for scalable, energy-efficient superconducting electronics.
We consider a model proposed before for a time-reversal-invariant topological superconductor which contains a hopping term ttt, a chemical potential $\ensuremath{\mu}$, an extended sss-wave pairing $\mathrm{\ensuremath{\Delta}}$, and spin-orbit coupling $\ensuremath{\lambda}$. We show that for $|\mathrm{\ensuremath{\Delta}}|=|\ensuremath{\lambda}|$, $\ensuremath{\mu}=t=0$, the model has an exact analytical solution defining new fermion operators involving nearest-neighbor sites. The many-body ground state is fourfold degenerate due to the existence of two zero-energy modes localized exactly at the first and last sites of the chain. These four states show entanglement in the sense that creating or annihilating a zero-energy mode at the first site is proportional to a similar operation at the last site. By continuity, this property should persist for general parameters. Using these results, we discuss some statements related to the so-called time-reversal anomaly. The addition of a small hopping term ttt for a chain with an even number of sites breaks the degeneracy, and the ground state becomes unique with an even number of particles. We also consider a small magnetic field BBB applied to one end of the chain. We compare the many-body excitation energies and spin projection along the spin-orbit direction for both ends of the chains obtained treating ttt and BBB as small perturbations with numerical results in a short chain, obtaining good agreement.
Abstract Back-action refers to a response that retro-acts on a system to tailor its properties with respect to an external stimulus. This self-induced effect generally belongs to both the natural and technological realm, ranging from neural networks [1] to optics [2] and electronic circuitry [3]. In electronics, back-action mechanisms are at the heart of many classes of devices such as amplifiers, oscillators, and sensors [4]. Here, we demonstrate that back-action can be successfully exploited to achieve non-reciprocal transport in superconducting circuits. Our device realizes a supercurrent diode, since the dissipationless current flows in one direction whereas dissipative transport occurs in the opposite direction. Supercurrent diodes presented so far rely on magnetic elements or vortices to mediate charge transport or external magnetic fields to break time-reversal symmetry [5-9]. In our implementation, back-action solely turns a conventional reciprocal superconducting weak link with no asymmetry between the current bias directions into a diode, where the critical current amplitude depends on the bias sign. The self-interaction of the supercurrent with the device stems from the gate tunability of the critical current, which uniquely promotes up to 88% of magnetic field-free signal rectification and diode functionality with selectable polarity. The concept we introduce is very general and can be applied directly to a large variety of devices, thereby opening novel functionalities in superconducting electronics.
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