A quantum diffractor for thermal flux

Abstract

Macroscopic phase coherence between weakly coupled superconductors leads to peculiar interference phenomena. Among these, magnetic flux-driven diffraction might be produced, in full analogy to light diffraction through a rectangular slit. This can be experimentally revealed by the electric current and, notably, also by the heat current transmitted through the circuit. The former was observed more than 50 years ago and represented the first experimental evidence of the phase-coherent nature of the Josephson effect, whereas the second one was still lacking. Here we demonstrate the existence of heat diffraction by measuring the modulation of the electronic temperature of a small metallic electrode nearbycontacted to a thermally biased short Josephson junction subjected to an in-plane magnetic field. The observed temperature dependence exhibits symmetry under magnetic flux reversal, and clear resemblance with a Fraunhofer-like modulation pattern. Our approach, joined to widespread methods for phase-biasing superconducting circuits, might represent an effective tool for controlling the thermal flux in nanoscale devices.

Radiation comb generation with extended Josephson junctions

“…The original prediction of π jumps 8 has also been indirectly confirmed via measurements in heat transport experiments performed in temperature-biased Josephson tunnel junctions 15,16 . Indeed, as it is explained in Ref.…”

Hysteretic Superconducting Heat-Flux Quantum Modulator

“…However, since the area of the SQUID ring is usually greater than the area of the junctions, this modulation occurs on a field scale much larger than the modulation period of thermal currents in the SQUID. Moreover, JJs in the so-called overlap geometry are usually preferred in SQUID-based applications [5], so that the magnetic field threading the loop is out-of-plane to the junctions area and no modulation of the critical currents occurs. Therefore, hereafter the junction critical currents I J are assumed independent of the external flux variations.…”

“…Recently, the features of the phase-coherent thermal transport in Josephson devices have been investigated and confirmed experimentally in several interferometer-like structures [2][3][4][5][6][7][8][9]. In Ref.…”

“…[5] by the observation of thermal diffraction patterns in a flux driven, temperature-biased "short" rectangular tunnel JJ. When a temperature-biased extended JJ is threaded by a magnetic flux, a Fraunhofer-like diffraction pattern, i.e., ∝ |sin(πΦ/Φ 0 )/(πΦ/Φ 0 )|, for the drain temperature is observed [5].…”

Temperature-Dependent Transformation Thermotics: From Switchable Thermal Cloaks to Macroscopic Thermal Diodes

“…Fortunately, the past years have witnessed the possibility of manipulating phononic [1][2][3][4][5][6][7] or electronic [8][9][10][11] heat conduction at the nanoscale, which provides a promising method to make use of heat flux. So far, significant progresses have been made, such as computation [3], information storage [4] and caloritronics [8,9]. On the contrary, steering heat conduction at the macroscale is still far from being satisfactory [12], which prohibits macroscopic thermal rectification for diverse thermal management problems, e.g., efficient refrigerators, solar cells, and energysaving buildings [13][14][15].…”