Physicists have recreated the Nobel Prize–winning quantum Hall effect using light, revealing that photons can follow the same strange quantum rules once thought exclusive to electrons.
In the late 1800s, scientists discovered what is now known as the Hall effect. It occurs when an electric current passes through a material while a magnetic field is applied at a right angle to the current. Under these conditions, a voltage appears across the material in the sideways direction.
The reason is straightforward. The magnetic field pushes negatively charged electrons toward one side of the conductor. As electrons gather along that edge, they create a buildup of negative charge, while the opposite side becomes positively charged. This separation produces a measurable voltage across the strip.
Researchers have relied on this voltage difference for many decades. It provides a precise way to measure magnetic fields and to determine material doping levels, that is, the addition of a tiny, controlled amount of impurity to a pure material to change how it conducts electricity.
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