Today's quantum computers are complicated to build, difficult to scale up, and require temperatures colder than interstellar space to operate. These challenges have led researchers to explore the possibility of building quantum computers that work using photons—particles of light. Photons can easily carry information from one place to another, and photonic quantum computers can operate at room temperature, so this approach is promising. However, although people have successfully created individual quantum "logic gates" for photons, it's challenging to construct large numbers of gates and connect them in a reliable fashion to perform complex calculations.