Nicole Yunger Halpern

In a dark laboratory where superconducting chips are cooled to thousandths of a kelvin, a qubit spins under the influence of a magnetic field. A regular qubit rotates in one direction. An antiqubit, its mirror twin, rotates in the opposite direction. Together they form a pair that senses the field twice as sharply as any ordinary pair.

In the 19th century, James Clerk Maxwell imagined a tiny demon. It knows the speed of every gas molecule and opens a door: fast ones to the left, slow ones to the right. This creates a temperature difference without expending energy, seemingly violating the laws of physics.