  The significance of the superconducting diode effect lies in its potential
application as a fundamental component in the development of next-generation
superconducting circuit technology. The stringent operating conditions at low
temperatures have posed challenges for the conventional semiconductor diode,
primarily due to its exceptionally high resistivity. In response to this
limitation, various approaches have emerged to achieve the superconducting
diode effect, primarily involving the disruption of inversion symmetry in a
two-dimensional superconductor through heterostructure fabrication. In this
study, we present a direct observation of the supercurrent diode effect in a
NbSe2 nanobridge with a length of approximately 15 nm, created using focused
helium ion beam fabrication. Nonreciprocal supercurrents were identified,
reaching a peak value of approximately 380 $\mu$A for each bias polarity at
$B_{z}^{max} =\pm 0.2$ mT. Notably, the nonreciprocal supercurrent can be
toggled by altering the bias polarity. This discovery of the superconducting
diode effect introduces a novel avenue and mechanism through nanofabrication on
a superconducting flake, offering fresh perspectives for the development of
superconducting devices and potential circuits.
