Chip Changes Photon Color While Preserving Quantumness

A new device-on-a-chip converts visible light to infrared wavelengths in a way that preserves the quantum states of the photons. This microscopic structure can be produced in large numbers on a single chip. The visible photons to be converted could be the delicate data bits from a quantum computer that need to be transmitted long distances over infrared-friendly fiber-optic cables. The device consists of a tiny ring of semiconductor (called a microring) that, when hit with intense infrared laser light, causes visible photons in the ring to convert to infrared. Together, many microrings on a chip could enable easy conversion of the large numbers of photons that a future quantum computer might need to transmit.